Dietrick Papers: Published Talks and Articles

by Everett J. "Deke" Dietrick

Everett Dietrick's Five Features of IPM

Argentine Ants Must Be Suppressed

 

Commercial Production of Entomophagus Insects and Their Successful Use in Agriculture in BIOLOGICAL CONTROL IN CROP PRODUCTION

 

Biological Control By Farmer Insectaries

 

Diversity and Refugia Make Biological Pest Control Work

 

Integrated Pest Control - Theory And Practice

 

Biological Control:An Ecological Approach

To Pest Management For Farms, Ranches, & Gardens

 

 

Everett Dietrick's Five Features of IPM

The five points below follow the outline of "The Five Features of IPM" set forth by Everett J. (Deke) Dietrick in 1969. Examples are given of how all five features — avoiding disruptive pesticides, building beneficial refuge, monitoring insects, developing cultural practices, and releasing beneficial organisms — favor the development of cost effective pest control.

 

1 -- Avoid use of disruptive pesticides

 

Food drives these systems, when you kill pests, you are killing the food or host of beneficial insects. Even seemingly safe pesticides may kill fungi on leaves that is a secondary food for some beneficials. Spray only if there is a pest problem! Repeated use of all classes of chemical poisons on your farm results in pest resistance to the poisons. The natural enemies of pests are also killed, or are starved away from the fields, and, therefore, do not have an equal chance to develop resistance as do the pests. Predators and parasites do not leave completely, but their numbers are significantly reduced compared to pest numbers. It sometimes takes several generations of beneficials to grow back the natural balance.

 

Certain dosages of conventional pesticides and insecticidal soaps and oils selectively kill pests and are less disruptive to biological controls. Our beneficials are compatible with "soft pesticides" like microbial insecticides, sterile male releases and pheromone mating disruption. The use of pyrethroids and broad spectrum pesticides is recommended only in extreme cases, as these kill many beneficials as well as pests.

 

2 -- Build beneficial refuges

Strip or trap cover crops that are never sprayed offer a field insectary and winter refuge for beneficial insects without harm to market products. Parasites live several times longer and destroy more pests when there are weeds or other plants to provide pollen, nectar and refuge. Think of giving up 1% of your field for pest control. Much of this 1% can come from roadsides, borders, box ends and row ends. Sunflower and sorghum borders are particularly good habitats for growing lacewing and other natural enemies on the farm. Corn and alfalfa borders and interplantings of flowering plants can also increase Trichogramma parasitism of moth eggs in the crop. You can use trap crops to draw pests from your crop and raise beneficials on them. Corn is more attractive than cotton for corn earworm (=cotton bollworm) so interplant corn with a cotton crop. Trichogramma released on the corn can be found racing up and down silks parasitizing corn earworm eggs.

 

3 -- Monitor Insect Ecology

Whatever is done in any field situation is always founded, as far as possible, upon the full knowledge of the interactions and ratios of the pests and their natural enemies. Therefore, monitoring should involve thorough sampling and observation of relative numbers of pests and all beneficials. Develop a system for scouting and assessing general trends in the change of pests and generalist predators in a given field as a guide for treatment or no treatment. You don’t have to count all the insects, just observe the ratio of pests to beneficials. One of the most important tools for monitoring is the D-Vac vacuum insect net. [Editors note: Everett helped invent the D-Vac and has produced them for forty years. He uses it to show farmers the progress of biological control, especially the tiny forms.] Keeping track of the beneficials and seeing the ratios of good and bad bugs makes it possible to predict damage thresholds in time to keep the yields optimum. D-Vac samples placed in alcohol and examined under a dissecting microscope show the progress of the entire natural enemy complex and is practical for decision-making. Whatever is done in any field situation is always founded, as far as possible, upon the full knowledge of the interactions and ratios of the pests and their natural enemies. Therefore, monitoring should involve thorough sampling and observation of relative numbers of pests and all beneficials. Develop a system for scouting and assessing general trends in the change of pests and generalist predators in a given field as a guide for treatment or no treatment. You don’t have to count all the insects, just observe the ratio of pests to beneficials. One of the most important tools for monitoring is the D-Vac vacuum insect net. [Editors note: Everett helped invent the D-Vac and has produced them for forty years. He uses it to show farmers the progress of biological control, especially the tiny forms.] Keeping track of the beneficials and seeing the ratios of good and bad bugs makes it possible to predict damage thresholds in time to keep the yields optimum. D-Vac samples placed in alcohol and examined under a dissecting microscope show the progress of the entire natural enemy complex and is practical for decision-making.

 

4 -- Develop cultural practices

Slight changes in farming to take advantage of the known behaviors of both the pests and the beneficials that attack them can avoid the pest flare-ups taken for granted under conventional chemical farming. Techniques of crop rotation, hedging and refuge management can make a difference. Strip cutting (harvesting alternate strips or fields of alfalfa or cover crops when they begin to bloom), for example, forces a steady migration of beneficials into nearby row crops yielding many times the natural enemies of uniformly cut hay fields or cover crops.

 

5 -- Release beneficial organisms

Rincon-Vitova distributes many biological control organisms; predators, parasites, . These organisms attack different pests, sometimes target specific life stages, and often attack during a particular season. Ideally, releases are started as early in the season as possible, when the first pests enter fields. While each farm and season is unique, growers and pest control advisors can draw on Rincon-Vitova's reviews of published findings of biocontrol entomologists and experience to build a program tailored to their situation.

 

The primary purpose of following the five features above is to conserve natural enemies. IPM emphasizes beneficials and seeks to suppress particular pest levels so that rather than pest numbers rising explosively, they stay within tolerable damage levels with minimum loss of beneficials. 100% mortality of all pests is not required to prevent economic losses to the market crop. The IPM method gets easier each year, as a reservoir of natural enemies becomes established.

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Argentine Ants Must Be Suppressed

by Everett J. (Deke) Dietrick, President, Rincon-Vitova Insectaries

 

The exotic Argentine ant, Linepithema humile (formerly Iridomyrmex humilis (Mayr)) can quickly spread over large areas of farms and greenhouses. A rise in honeydew-secreting insect pests follows such invasions of Argentine ants. Good biological control is not possible unless honeydew-seeking ants are suppressed.It is well documented that large populations of Argentine ants can cause disruption of all the diverse sets of predators and parasites and antagonists involved in biological control. These ants eat beneficial insects and keep many beneficials away from plant-sucking prey, harvesting the insect honeydew for themselves.

 

When honeydew-secreting insects like aphids, whitefly, and soft scale flourish, they attract more beneficials. They even attract beneficials away from other crops and plants where there are no ants. Once they enter ant-infested plants, they are eaten, providing the protein to go with the carbohydrates in the insect honeydew. Such a balanced diet is so nourishing that the ants quickly produce multiple queens and more colonies.

 

The actual decimation of beneficial insect populations is most evident in those plants that are at the interface; in other words, where there are plants both with and without ants. That is where the battle of good and bad bugs is raging and the ants usually prevail. Ants may even transport certain aphids and other insects or store them in the nest for protection and future use to start new colonies after a crisis.Edward 0. Wilson, Harvard professor and expert on ants, says in his book Diversity of Life, "...the prevalence of ants must have something to do with their advanced colonial organization. A colony is a super organism, an assembly of workers so tightly knit around a mother queen as to act like a single, well-coordinated entity. A wasp or other solitary insect [a natural enemy] encountering a worker ant on its nest faces more than just another insect. It faces the worker and all her sisters, united by instinct to protect the queen, seize control of territory, and further the growth of the colony. Workers are little more than kamikazes, prepared--eager--to die in order to defend the next or gain control of a food source. Their deaths matter no more to the colony than the loss of hair or a claw tip to a solitary, animal.

 

"Again quoting from Wilson: "There is another way to look at an ant colony. Workers foraging around their nest are not merely insects searching for food. They are a living web cast out by the superorganism, ready to congeal over rich food finds or shrink back from the most formidable enemies. Superorganisms can control and dominate the ground and treetops in competition with ordinary, solitary organisms, and that is surely why ants live everywhere in such great numbers.

 

"Conventional pest management fights them with pesticides. Since most of the ants in a colony are beneath the ground surface in the nest working to protect the queen and tending the brood, the applications of pesticides has little direct effect on the colony. Management comes from destruction of all food sources above ground and from residues left that are toxic by contact. Ant colony reduction occurs mostly from starvation which forces reduction of the colony through cannibalism on the young to save the integrity of the colony.

 

Ants can cause both primary and secondary pest outbreaks. We recently saw tomato russet mite in the tomatoes in an organic vegetable greenhouse where Argentine ants were thriving on honeydew from aphids spreading along ant trails. A conventional grower would have sprayed for aphids, reducing the food supply to the ants and slowing down the whole process of ant-induced aphid damage, but might not have sought a root cause that would have prevented the need of pesticide in the first place.

 

Being an organic grower, biological control was desired and indeed a great deal of biological control activity was present. Though some of the aphid species did not have parasitoids, a parasitoid of green peach aphid, Aphidius matricariae, was present on the pepper plants. It was able to evade the ants, but it arrived too late and worked too slowly without the help of predators. Plenty of ladybugs came in, but their effectiveness was deterred by ants and their eggs and larvae offered more nutritious food for the ants. Releases of green lacewing to help the ladybugs and aphid parasitoids, only provided additional protein for the ants.

 

The Aphidius parasitoid eventually, temporarily eradicated green peach aphid and saved the peppers, after which a rise in hyperparasites of Aphidius brought the system into equilibrium. However, the ants immediately threw it off balance again. Where the ants had caused the secondary mite outbreak on the tomatoes, it was a pretty hopeless situation that could have been avoided.

 

The effects in citrus were studied many years ago. Where ants were excluded or removed, biological control was optimized. Where ants were allowed to interfere, all pests of citrus were observed to increase. When augmentation of natural enemies is an option, it is only cost-effective when ants are excluded. Biological control by natural enemies cannot be evaluated fairly in the presence of Argentine ants any more than it can in the presence of dust and pesticide drift.Argentine ants form new colonies rapidly wherever scouts mark out food sources. In spring and summer, there is a progressive increase. Cool weather slows ant activity and allows struggling populations of beneficials to destroy pests on many plants. When old crops that are left in the field are ant-infested, the decaying plant material, which is normally a useful habitat for beneficials, only serves this role for the benefit of ants. While wet or foggy weather slows ant activity, heavy winter rains will drive ants from rain-soaked fields into greenhouses, houses, and barns.

 

Argentine ants can be baited with several ant syrups that have poisons. When the bait is carried to the nest and fed to the brood and poisons the queen, the colony is destroyed. A new queen must be fed the royal food that transforms her into a queen. This takes time which can then be spent disrupting ant nests by irrigation, cultivation, and reduction of old crops, and also repeated trail disruption. Ants do not nest where growing plants or mulches cover the ground. They prefer sun-baked soil to nest under and may even clean the nest area of vegetation in order to warm their nests. But they also need water. Drip irrigation lines provide a perfect source of water and serve like highways for the movement of ants to form new colonies. Unplanted borders near irrigation ditches can be chronically infested with ants.

The lifecycleof the Argentine ant from UC IPM Pest Notes #12

June 1995

 

We believe limited populations of ants may perform a useful service by creating "pest spots" that attract and support the development of populations of beneficials. This beneficial phenomenon is taking place; however, it does not warrant that growers try to conserve ants. It is virtually impossible to eradicate ants and if growers will attack them on all fronts, there will always be plenty left to provide the service of attracting beneficials. It is much better if ant-induced "pest spots" occur in refuge covercrops and not in market crops. Ants can spread like wildfire. It is easier to control a fire when it starts and is still small. The fire runs out of fuel and stops. Once the fire is spreading, it is very difficult to control.

 

Quick-fix pesticides have disguised the role that ants play in biological control of agricultural crops, so ant research has not been focused on how to suppress ants at tolerable levels. When the role of ants is not recognized, growers trying to reduce pesticide use and transition to organic farming practices may end up throwing money away on commercial natural enemies. It is not sufficiently emphasized how essential ant management is for the successful use of biological control by natural enemies.Note

 

The argentine ant is now established throughout the southern states and California. Isolated infestations have been reported from Missouri, Illinois, Maryland, Oregon and Washington.

 

Characteristics of an Ideal Bait

Strategies for baiting social insects are somewhat different than baiting other pests. Foraging ants gather food and then take it back to the nest to feed other members of the colony (trophallaxis). Only a small percentage of the nest is foraging at any one time. If a bait acts too swiftly. foragers will die before they are able to poison the rest of the colony, and most of the colony will escape. New foragers see the old ones dying, avoid the bait and move the colony. A good ant bait, then, must show delayed action. One definition of delayed action is less than 15% mortality after 24 hour exposure and better than 89% mortality in 20 days (Knight and Rust 1991; Stringer et al. 1964). However, even a bait toxicant that does not meet these standards may still give relief from an infestation.

 

As well as being slow acting, effective doses of the toxicant cannot be repellent. Repellency is to some degree overcome by using an enticing bait matrix. If a colony has been starved by effective sanitation measures, baits are also accepted more readily. Non-repellency might be the most important bait characteristic because if the bait is not taken by foragers, nothing happens at all.Baits must also be readily transferred by trophallaxis. For worker exchange, the bait must be liquid or chewed into very small particles. The physical state of the food is not a problem with larvae, as they are able to eat either solids or regurgitated liquids.

 

A bait should show delayed action over at least a 10- to 100-fold dosage range. This requirement is necessary due to dilution of the bait during trophallaxis. Enough residual poison must remain after regurgitation to kill the foragers, and the amount delivered must be concentrated enough to do the job, even if it is spread among a number of larvae.

 

Finally, relatively large amounts of the bait must not be poisonous to non-target species. For instance, if a dog ate a whole bait station, nothing should happen (Stringer et al. 1964).

Reprinted from Common Sense Pest Control Quarterly page 7, Vol. XI, No 4, Fall 1995 by permission

 

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Commercial Production of Entomophagus Insects and Their Successful Use in Agriculture

 

by E. J. DIETRICK*Published in: BIOLOGICAL CONTROL IN CROP PRODUCTION (BARC Symposium number 5-George C. Papavizas. ed.) Allanheld, Osmun, Totowa, p 151-160, 1990

 

ABSTRACT

The commercial insectary is defined as a free enterprise business offering live predatory and parasitic insects (parasitoids) over the counter. Emphasis is on their commercial marketing and successful use in agriculture, rather than any particular mass production techniques applicable to the entomophagus arthropods offered for sale. Conclusions are based on the author's 35 years of personal experiences: 15 years of employment in classical biological control research at the University of California, Riverside, and more than 20 years in management of a commercial insectary.*Rincon Vitova Insectaries, Inc., P. 0. Box 1555, Ventura, California 93002.

 

INTRODUCTION

The commercial insectary, financially supported by sales of entomophagus arthropods beneficial to agriculture, has grown from humble beginnings into the somewhat sophisticated business enterprise of insect farming and marketing. The business has advanced from harvesting hibernating ladybird beetles to using labor-intensive, mass production techniques, which keep all stages of each species of carnivorous predators and the substitute host used as food in continuous production. Like farming, the growing of many different species has great complexity peculiar to each species, and there may be several equally effective ways to mass culture any one of them. Therefore, I have chosen not to dwell on rearing methods. There are excellent comprehensive publications available on insectary facilities, equipment, and methods useful in the culturing of entomophagus insects (DeBach 1974; DeBach and Schlinger 1964; Fisher 1963; Huffaker and Messenger 1976; Leppla and Ashley 1978; Ridgeway and Vinson 1977; Smith 1966).

 

Evolution of the commercial insectary and its marketing techniques are outlined from inception to a modern practical alternative to the count-and-spray programs of pest management that are advocated by chemical company sales propaganda. Problems facing further advancement of the insectary as a business are discussed. A favorable assessment is given for the future expansion of many small businesses composed of pest control advisors working independently for individuals or groups of farmers. They may or may not own insectary facilities, but they will be applying cost-effective biological controls wherever and whenever it is practical in integrated pest management programs. Finally, an assessment is made of the existing situation, with suggestions that would help this kind of business to develop.

 

For the purposes of this discussion, biological control will mean the use of mass-cultured and/or field-harvested predators, parasites (parasitoids), and various naturally occurring microorganisms that cause epizootics of arthropod populations and can often be harvested and stored for future use. I exclude from my concept of biological control such expanded meanings as third-generation pesticides or those microbial pesticides that have been registered. The natural enemy complex refers to the full range of organisms, minor pests, decomposers, competitors, and antagonists that are recognizable in biologically balanced, field situations, i. e., the untreated, commercially clean field that produces marketable products.

 

INSECTARIES THAT DEPEND ON FIELD-HARVESTED SOURCES

Among the many reasons for culturing entomophagus insects, probably the most straightforward one is that it is common sense to promote biological control. Most of us who have gardened have seen ladybird beetles feeding on aphids. Why wouldn't one wish to help this natural enemy of a garden pest? Probably the first farmers in history were aware of the more-obvious insect predators that were observed feeding on phytophagous insect pests. This urge to help the "good" insects is still strong among farmers. In spite of considerable efforts to discredit the practice, the mountain-collected ladybird beetle, Hippodamia convergens Guerin, is still the most-marketable product sold by commercial insectaries. Egg cases of the praying mantids are also harvested, although to a lesser extent than the thousands of gallons of ladybird beetles. Market demand for both of these species far surpasses the supply in most years, even though neither of these beneficial insects is likely to reduce substantially the populations of any particular target pest.The major problem associated with marketing field-harvested products is their limited availability. It is economical to harvest only when large populations occur in limited space. Also, the product usually has aged or is ready to enter an aggregation or diapause state in its development. Other problems that are common to all products offered by commercial insectaries and that limit the marketing of field-harvested predators are as follows: (a) the desired species must be separated from chaff and living plant material; (b) refrigerated storage is required to slow the activity sufficiently to facilitate separation of the desired species and prevent exposure losses; and (c) the harvest must take place under conditions that prevent loss of quality, e.g. air conditioning. Many of these products are extremely tiny, fragile, and require special packaging for containment on the way to market. Finally, such beneficial insects are poorly understood by most potential customers and by entomologists.

 

Those commercial ventures that depend on field-harvested sources for their products have certainly helped to keep alive the concept of biological control throughout an age of massive reliance on chemical pesticides. The red ladybird beetle collected each winter and marketed the next spring has been the symbol representing the "good bug" that has exposed as a myth the chemical company advertising slogan "the only good bug is a dead bug."

 

Many farmers buy these beetles every year because their experience with them has been good. It is very difficult to convince them that many other species of predators might be responsible for their good fortune or that the insects they bought probably flew away. Nevertheless this receptive response or urge to believe in the benefits of utilizing natural enemies has made it possible for pest control advisors to communicate with farmer clients about biological control and thereby develop a market for other, more-useful species.

 

PEST MANAGEMENT WITH NATURAL ENEMIES

My experiences in classical biological control research, while employed at the University of California, gave me a strong appreciation for the full, natural enemy complex that can exist on farms not exposed to the adverse effects of pesticides. Most of my time was spent in citrus, cotton, and alfalfa fields, comparing various predator and parasite exclusion methods on small plots in unsprayed farms (DeBach, Dietrick, and Fleschner 1949). We measured the effects of pesticides on various species of beneficial insects that controlled certain pests. We developed methods with the use of pesticides and other habitat-disturbance techniques, e. g. DDT checks, dust checks, and ant checks, to encourage the buildup of pest populations by selectively destroying the natural enemies. We subsequently observed the return of biological control organisms in these plots and monitored the biological suppression and cleanup of these deliberately created pest infestations. We also experimented in fields with pest problems created by ant and excessive dust interference to natural enemies, and then obtained pest control by the elimination of these interferences. Various harmful effects of pesticides were investigated in many different crops, and the results were similar to the pest population outbreaks created by our interference experiments. Such procedures for fostering pests (DeBach 1974) by the elimination or even selective suppression of natural enemy populations without affecting similar control of the pests showed the value of natural enemies in pest management programs.

 

These experiences helped us to identify the reasons why there was such a difference of opinion among entomologists about biological control. Chemical control advocates generally ran their test plots in fields where the target species flourished. It was logical that they seek those fields in order to obtain the data needed about the effects of pesticides on those pest species. These fields were high in pests and low in predators and parasites. Conversely, entomologists interested in biological controls ran their studies in fields that had relatively large populations of predators and parasites compared to pests. Their experimental requirements needed fields free from pesticide and other habitat interferences to explore the effects of natural enemies and specific biological control agents on their host populations.Clearly, these were two different kinds of field situations. The former was deficient in predators and parasites. Even those natural enemies present were destroyed under the small plot experimental design. Pesticide drift and interplot migration of the more-mobile predators and parasites adversely affected the biological control that was present. The latter biological control experimental field situations were isolated from effects of pesticides, and the full range of natural enemies were present. Large experimental plots were used to minimize the drift effects from any pesticides used.

 

There is little wonder that there exists such a divided opinion among entomologists regarding biological controls. It is difficult to form a good opinion about natural enemies if there are none in the fields chosen for studies.The devastating interpretation of this situation occurred when the untreated check plots in the small plot pesticide screening experiments were referred to as being representative of biological control failures. Instead of measuring the ineffectiveness of the natural enemies (or lack of them) these entomologists demonstrated the detrimental effects of pesticides on those few predators and parasites that were attracted to these check plots in search of their prey. These checks were pesticide interference plots.

 

Conclusions on economic thresholds were derived from such fields that were deficient in natural enemies. The lack of any biological control suppression on the pest populations led to the setting of pest density levels that were far too low for fields where natural enemies were allowed to help suppress the pests. Pest management with natural enemies can flourish where population monitoring allows for minor pest spots to appear in fields in order to attract and multiply the natural enemy complex that will predictably control the pests and result in a marketable harvest.

 

Pest control advisors face three kinds of fields each time they check the farms of their clients. Clean fields are quickly identified and little time is spent in them. Dirty fields full of pests with few natural enemies are also quickly managed by making the proper pesticide recommendation. Most of the advisors' time is spent monitoring the insect populations in the borderline fields, which are not clean of pest species but have a moderately high level of natural enemies. There is time to watch and wait, because the pest populations do not Increase as quickly where natural enemy suppression is occurring. Some of these develop sufficient natural enemies for the pests to be biologically controlled and the use of pesticides can be avoided.

 

Farmers who buy biological control products try to help the natural enemies in these borderline fields. This commonsense idea of periodic augmentation of insectary products in infested fields to help the natural enemy suppression of the pests is the foundation for the use of such biological controls in agriculture. Such pest management is based on principles of ecology, the recognition that 100% mortality of all pests is not desirable, and on attempts to avoid as much as possible the impact of pesticides and other habitat disturbances on beneficial insects (DeBach 1969, 1974; Dietrick 1972; Kilgore and Doutt 1967).

 

EVOLUTION OF THE FREE ENTERPRISE INSECTARY

Rincon Vitova Insectaries, Inc., began as a part-time partnership, Rincon, growing "Crypts'," a mealybug-destroying coccinellid named Cryptolaemus montrouzieri Mulsant. This Australian predator had been mass-cultured for many years by county government insectaries, individual farmer-owned insectaries, and farmer association insectaries (Fisher 1963). The county effort, which had used tax money for support but gave the insects to farmers free of charge, was discontinued for budgetary economy and other reasons. A ready market for rearing and selling these beetles thus became available. It quickly became clear to us that this potential market would not develop. The weak endorsement for these inoculative-type releases from nearly all agricultural researchers, coupled with the euphoria for chemical pesticides, almost completely stopped the use of this product. Crypts are still used today by our insectary, and at least one citrus farmer cooperative insectary continues to grow several millions of these beetles each year, as it has for nearly 50 years. The lesson that Rincon Insectary learned was that farmers would not necessarily buy products that were previously obtained free of charge.Rincon Insectary then found a market for "Trichos," a trichogrammatid parasite of eggs of the cotton bollworm moth, Heliothis zea Boddie (now Heliocoverpa zea), that were being cultured by a farmer in west Texas. The potential market for these Trichogramma spp. was larger than the supply. Costs for production were greater and less reliable in Texas than in Rincon' s coastal climate, and an agreement was reached for Rincon Insectary to grow the insects and the Texas partners to market them. In spite of the controversy that had raged over inundative releases of Trichogramma spp. (DeBach and Hagen 1964), the farmers were eager to acquire and use the product. Rearing methods first proposed in the early twenties were resurrected (Flanders l930, l934). The farmers bought Trichos for the same reason that they bought ladybird beetles: the results were satisfactory, and it was commonsense to help the existing natural controls. This west Texas cotton-growing area was blessed with large populations of natural enemies, and the use of ladybird beetles, Trichos, or any other species of insects known to help suppress bollworm populations would have satisfied the customers. These products were more economical than pesticides and their use lessened the farmers' worry when cotton bollworm moths were reported to be flying. They provided the pest control advisors a logical alternative product to counteract the fear generated in the farmers by the unrealistic economic thresholds set for bollworms. The recommendation to treat for bollworms, when 4 out of 100 cotton plants were infested with eggs of bollworm moths, was clearly set too low for fields that had natural enemies that were destroying these eggs. The Trichos released to) help attack the populations of bollworm eggs was a commonsense approach. The results were generally favorable in fields that had not received earlier applications of pesticides for such minor pests as thrips, aphids, and mites. The natural enemies in these untreated fields had been allowed to increase their populations on these minor pest problems, thus controlling them biologically. (The questionable recommendation to "clean up these early pests so biological controls could work" had not yet reached these farmers.)

 

With the natural enemy complex capable of control, many farmers experienced good results solely with releases of Trichos. With the use of D-Vac (trade name for sampling equipment manufactured by D-Vac Company, P. 0. Box 2095, Riverside, CA 92516) vacuum insect sampling equipment, we were able to show customers that most bollworm eggs were destroyed and that the few one-day-old worms that did emerge were victims of predators before they grew to be three to four days old (Dietrick 1961; Dietrick, Schlinger, and van den Bosch 1959). The low survival rate of these eggs and small worms was shown to be a measure of the effectiveness of biological control. These observations eventually resulted in economic thresholds being raised for untreated cotton fields. The 1973 cotton pest and disease control guide of the Division of Agricultural Sciences, University of California, states: "In fields not previously treated for insect control, insecticide treatment (for bollworms) is indicated when 20 small worms per 100 plants are found." This economic threshold was compatible with the use of insectary products.

 

The door was open to begin talking to more and more cotton farmers about biological control. We showed them fields where effective populations of predators and parasites destroyed bollworm eggs overnight. We also were able to explain to the farmers that, in those field situations where nearly all bollworm eggs hatched and grew into full-grown worms, there was no buffering natural enemy complex to suppress these pest populations and much cotton was destroyed as a result.

 

About that time Rincon learned another lesson about the insectary business. The marketing partner in Texas decided to build his own insectary with funds collected from farmers and owed to Rincon. As a result, we lost over 80% of our business and gained a bad debt as well. This was only the first of many such experiences. The method of payment for insects came long after harvest and the delivery of our products, but the insectary borrowed the money to set the cultures six months in advance of the market. The live insect products were grown, delivered, and released on the farms throughout the growing season. Usually, only after the farmer sold the crop, did he pay the insectary. Since biological controls were not considered pest controls, they could not be included in the bank loans set aside for chemical pesticides and other production financing. Some farmers simply never paid; after all there was no) proof that releasing Trichos had helped. The problems of late payment and bad debts are enough to make most potential investors shy away from this business.

 

Fortunately, there was sufficient financial support to keep us in the struggle. We found new markets, diversified our product line, and broadened the areas where we sold these products. One such market developed in citrus with the use of the golden chalcid parasites, Aphytis lingnanensis Compere and A. melinus DeBach. These species attack the number one pest of citrus, California red scale, Aonidiella aurantii Maskell (DeBach 1969). One of the farmer cooperative insectaries contracted with Rincon to buy 5 million of the red scale parasites. At the same time, we borrowed a program from these farmer cooperatives and began contracting with individual farmers for pest management advice and beneficial insect colonizations wherever they might be located. We insisted that the advice services include releases of our insectary grown products. Trichos were for cotton and the crypts and Aphytis spp. were used as periodic inoculative releases in citrus. The charge per ha set by the farmer cooperative insectaries was increased to cover the additional travel costs, the costs of field monitoring advice, and the insectary products. This seasonal contracted market gave our business some stability and provided compensation for all the extra insect products that we grew, but could not sell over-the-counter. The only real difference between our operation and the farmer cooperatives was the voluntary participation on the part of our clients. My observation about these farmer cooperatives is that it is difficult to please continually all of the individual member farmers.

 

This voluntary, professional-client relationship gave our effort considerable freedom for direction. We simply had to please enough farmer clients in order to pay our expenses. Profits could come from the over-the-counter sales of insect products. Some farmers wanted to believe in sophisticated pest control advice, and we convinced them to buy the insects. Other farmers wanted to believe in the augmentative releases of predators and parasites, so we sold them the insect products and tried to follow up with advice where possible. We contacted other independent pest control advisors and found a few of them willing to use our products as part of their advice programs. Even competing insectaries have on occasion purchased our products to help fill their market needs.

 

These professional-client contracts were more like verbal agreements, but they provided enough cash flow to keep the business going. Even the late-paying customers provided a winter income when the payments finally came in. We avoided any business ties that would obligate us to any particular market or dealerships. We grew as many insects as possible with the resources available and used them in our pest management or sold them as the market developed. We had solved the problem of how to be compensated for all the insects that flowed daily from the production units, at least during the summer growing season.

 

The arrival of the pink bollworm, Pectinophora gossypiella Saund., as a new pest species in our cotton marketing area, triggered an eradication effort by state and federal authorities. The blanket pesticide applications required by this effort immediately created another shock to our struggling insectary business. Adequate natural enemies for this pest were not available, and the eradication procedures advocated for its control were not compatible with our biological pest management programs. The effect on our Tricho sales was devastating.

 

One group of farmer clients, the Coachella Valley Growers Gin, had been our customers continuously since 1961. These farmers chose not to apply the pesticides in the eradication effort, and thus the federal authorities substituted the sterile moth releases as an eradication procedure. This program allowed for biological controls to be used early in the season even though chemical pesticides had to be resorted to in late season. We were thus able to continue our programs with these farmers.The business lesson we learned from this experience was how to be adaptable. We then adjusted our programs to the sterile moth eradication experiment. We found new markets to replace the lost ones in other cotton-growing areas. We helped ourselves by helping cotton farmers in Mexico) and Central America to further their insectary efforts. We also lengthened our marketing season by delivering our products to Nicaragua. We began a new line of parasites that helped biological control of pestiferous flies associated with manure accumulations on poultry farms (Legner and Dietrick 1972). These business-diversifying actions again created enough income to keep us going. During this time we added production facilities by purchasing another insectary known as Vitova (a contraction for the Latin vita ova meaning live eggs).Research has benefited our insectary a great deal. The existence of a commercial insectary challenged researchers to) investigate some of the programs that we intuitively advocated, doing what seemed obvious from our field observations. Influential farmer clients asked questions in important places, and research money flowed from various commodity groups for university and government researchers involved in such biological control efforts. Our insectary supported research and encouraged customers to fund such research (E. J. Dietrick, unpublished). The fallout of useful knowledge that comes from such ecological experimentation far surpasses any possible effects that any negative findings would have on our business. The problem still lies in finding the funds to study the Implementation of biological controls.

 

PROBLEMS FACING THE COMMERCIAL INSECTARY 

Problems encountered by commercial insectaries can best be solved in the free market place. Farmers will discontinue acquiring and using pesticides when they are convinced that alternative pest management is cost-effective. Rising costs for petroleum-based farm chemicals and fuels and narrowing profit margins are forcing farmers to look for more economical solutions than those presently available. Farmers presently spend millions of dollars every year for chemical pest controls that may not provide any permanent solutions to the problems. When farmers buy chemical pesticides, their support goes to further the development of more chemicals. Perhaps a financially viable biological control industry can also influence further research and development in classical biological control. Biological control importation projects are the main source of beneficial predators and parasites that can be developed as products by commercial insectaries.

 

Increasing energy costs are also influencing insectaries that serve the farmers. The appropriate ate size firm seems to be one which is small enough to adjust its products and services to) meet local needs. Maximum use of habitat management techniques that are capable of trapping pests and increasing the populations of predators and parasites can then be used (Schlinger and Dietrick 1960). Insect-harvesting equipment can be employed to move the surplus natural enemies from fields where pest populations have been destroyed to fields deficient in predators and parasites (E. J. Dietrick, unpublished; Stern 1969; Stern et al. 1964, 1965; van den Bosch l969). The local insectary can become abase for pest control advisors for such operations along with mass-culturing of certain parasites that can be more economically grown than harvested.

 

Probably the single most-prevalent problem facing the commercial insectary is the low visibility of biological controls. It would greatly help if extension efforts could provide farmers with biological control information with color pictures of the key predators and parasites associated with each crop. There are few bulletins that provide "do-it-yourself" assessments of key natural enemies (Bethell 1978; van den Bosch and Hagen 1966). Perhaps a periodic newsletter identifying the "good bugs'' and their relationship to) pest management would enhance the visibility of biological controls. Unfortunately, the usual endorsement from the entomological establishment, including many researchers in biological control, is reduced to) such statements as ''It won't do any harm to use them." Some of the more-optimistic statements are that "we do not have sufficient information to recommend for or against the use of Trichogramma, chrysopids, praying mantids, ladybird beetles or any other parasites or predators in the manner proposed for controlling agricultural pests" (U. S. Department of Agriculture 1968). Such position papers, presumably based on adequate information, make it very difficult to sell biological control products. Weak statements that call for conservation of natural enemies without identifying the species involved, or without specifying which pesticide to use to conserve the predators, are also) nonproductive.

 

There seems to be a strong effort to regulate biological control practices as if they were a threat to society similar to the poisons in our pesticides. Certainly, no) harm can result from predators and parasites known to attack pests and already established in the area. One major justification for the commercial insectary is to help with the further spread of newly established, exotic species and/or races when the limited research funds for such dispersal to) all farms are inadequate. This free market allows a free choice to farmers who want to improve their complex of species of predators and parasites by purchasing new strains of biological control products. Marketing strains that are known to mate with indigenous strains may increase the genetic capability of certain biological control agents (Bartlett and van den Bosch 1964).

 

Other issues that need to be resolved in order to help the commercial insectary industry have to) do with financing. The insectary is a farming venture without any of the advantages of a farm (production credit, etc.). The products are perishable, adaptable to agricultural production systems, and as other beneficial farm animals, should not be considered for sales tax: they help the farmer just as any other work animals that are given tax exemptions.

 

THE COMMERCIAL INSECTARY AND THE FUTURE

Like most businesses marketing products with little shelf life, the insectary needs a steady market to) survive; free enterprise insectaries cannot sustain many poor market years. Beneficial insect products must be sold once they are grown. All other insectaries operate from other financial bases, but the commercial insectary will be out of business if the farmer clients cannot pay. Other pest control products can be kept in readiness for problems to) develop, but the insectary must arrange for an orderly delivery of its products as they emerge daily from the production cages. Whenever possible, we must find enough farmer clients to buy the insectary products as part of a regular inoculative release program.

 

Most fields can be helped with insectary products only during a few months of the growing cycle. The insectary personnel must culture these animals 365 days a year in order to) have them available for the few weeks when needed. Out-of-season production costs with little or no off-season sales can take away much of the profits.There are no proprietary protections for insectary products. Anyone can pirate one of our employees, buy our products, and begin his own insectary business at much lower start-up costs than it takes to collect and culture the original colonies obtained from field-collected individuals. This satellite insectary can operate seasonally, closing the rearing operations in the off season. By stopping the rearing process completely, much of the labor costs can be saved. Beginning the rearing process again after a few months to clean up and sanitize the various pests that the insectary attracts is a distinct advantage, provided there is some one of the businesses that can provide the new stocks for the coming season. Such satellite insectaries need not overproduce. Instead, they can buy products from the other insectary to fill in shortages in production or satisfy a particularly good market. Such cooperation among those who) culture insects will help to promote the industry in the long run, though the short-term effects can be very frustrating.

 

The economic gap is rapidly closing for biological agriculture versus conventional farming that depends mainly on petroleum-based chemicals. The rising energy costs are likely to bring many changes in the future production of food and fiber. The commercial Insectary is already helping farmers to establish biological and cultural controls as the basis for pest management. Our business has grown out of the failures of existing pesticide-dominated programs that ignore many basic ecological principles. As long as pesticides were inexpensive and the repeated applications ultimately succeeded when the customary one or two failed, the alternatives available to farmers seemed fraught with unacceptable danger. Rising production costs and narrowing profit margins are forcing farmers to look seriously at pest management that is based on natural enemies and the help that commercial production of these entomophagus insects can give. Farmers need biological control because it is safe, permanent, and economical.

 

ACKNOWLEDGMENTS

The manuscript for this paper was reviewed by my colleagues in Rincon Vitova Insectaries, Inc., and friends elsewhere. I am particularly indebted to Drs. T. W. Fisher and Fred Legner for their comments.LITERATURE CITED

Bartlett, B. R., and R. van den Bosch. 1964. Foreign exploration for beneficial organisms. Pages 283- 304 in P. DeBach and E. I. Schlinger, eds. Biological Control of Insect Pests and Weeds. Reinhold, New York.
Bethell, R. S., ed. t978. Pear Pest Management. Div. Agric. Sci., Univ. of California.
DeBach, P. t969. Biological control of diaspine scale insects on citrus in California. Proc. 1st Int. Citrus Symp. Vol.2: 801- 15
DeBach, P 1974. Biological control by Natural Enemies. Cambridge Univ. Press, London.
DeBach, P.; E. J. Dietrick; and C. A. Fleschner. 1949. A new technique for evaluating the efficiency of entomophagus insects in the field. J. Econ. Entomol. 42: 546.
DeBach, P., and K. S. Hagen. 1964. Manipulation of entomophagus Species. Pages 429- 58 in P. DeBach and E. t. Seblinger, eds. Biological Control of Insect Pests and Weeds. Reinhold, New York.
DeBach, P., and E. I. Seblinger, eds. 1964. Biological Control of Insect Pests and Weeds. Reinhold., New York.
Dietrick, E. J. 1961. An improved backpack motor fan for suction sampling of insect populations. J. Econ. Entolmol. 54: 394- 95.
Dietrick, E. J. 1972. Private enterprise pest management based on biological controls. Pages 7- 20 in Tall Timbers Conf. on Ecol. Animal Control by Habitat Management, No. 4, Tallahassee, Florida.
Dietrick, E. J.; E. I. Schlinger; and R. van den Bosch. 1959. A new method for sampling arthropods using a suction collecting machine and modified Berlese funnel separator. J. Econ. Entomol. 52:1085-91.
Fisher, T. W. 1963. Mass culture of Cryptoloemus and Leptomastix--Natural enemies of citrus mealybug. Calif. Agric. Exp. Stn. Bull. 797.
Flanders, S. E. 1930. Mass production of egg parasites of the genus Trichogramma. Hilgardia 4:465-501.
Flanders, S. E. 1934. Sitotroga production. .J. Econ. Entomol. 27: 1197.
Huffaker, C. B., and P. S. Messenger, eds. 1976. Theory and Practice of Biological Control. Academic Press, New York.
Kilgore, W. W., and R. L. Doutt, eds. 1967. Pest Control-Biological, Physical, and Selected Chemical Methods. Academic Press, New York.
Legner. E. F., and F. 3. Dietrick. 1972. Inundation with parasitic insects to control filth breeding flies in California. Pages 129-30 in Proc. and Papers of 40th Ann. Conf. of California Mosquito Control Assoc.
Leppla, N. C., and T. R. Ashley, eds. 1978. Facilities for insect research and production. U.S. Dept. Agric. Tech. Bull. No. 1576.
Ridgeway, R., and S. B. Vinson, eds. I 977. Biological Control by Augmentation of Natural Enemies. Plenum Press, New York.
Schlinger, E. I., and E. J. Dietrick. 1960. Biological control of insect pests aided by strip farming alfalfa in experimental program. Calif. Agric. 14: 8-9.
Smith, C. N., ed. l966. Insect Colonization and Mass Production. Academic Press, New York.
Stern, V. M. l969. Interplanting alfalfa in cotton to control lygus bugs and other insect pests. Pages 55-69 in Tall Timbers Conf. on Ecol. Animal Control by Habitat Management, No. 1, Tallahassee, Florida.
Stern, V. M.; F. I. Dietrick; and A. Mueller. 1965. Improvement on self-propelled equipment for collecting, separating, and tagging mass numbers of insects in the field. J. Econ. Entomol. 58:949- 53.
Stern, V. M.; R. van den Bosch; and T. F. Leigh. 1964. Strip cutting of alfalfa hay for lygus bug control. Calif. Agric. 18: 5-6.
U. S. Department of Agriculture. 1968. Current status of research on the production and use of biological agents for controlling agricultural insect pests. Entomol. Res. Division, A. R. S., Washington, D. C.
van den Bosch, R. l969. The effect of harvesting practices on insect populations in alfalfa. Pages 47-54 in Tall Timbers Conf. Ecol. Animal Control by Habitat Management, No. 1, Tallahassee, Florida.
van den Bosch, R., and K. S. Hagen. 1966. Predaceous and parasitic arthropods in California cotton fields. Calif. Agric. Exp. Stn. Bull. 820.

 

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Biological Control By Farmer Insectaries

 

By Jan Dietrick and Everett J. (Deke) Dietrick, CPE, Rincon- Vitova Insectaries

 

Biological control by natural enemies is the only permanent, low-cost way to control insect pests. Combined with safety and environmental concerns and the documentation of hundreds of species now resistant to pesticides,. producers and consumers are getting smart about biological control. Despite the potential for solving pest problems biologically, funding is not being allocated to develop and promote reliable biological programs. Leadership in the way of funding from grower organizations is the most logical trend. Farmers specializing in specific crops in particular areas can benefit by spreading costs among themselves. The Fillmore Citrus Protective District is a well-known example of the farmer-financed insectary. Growers organized in the late 1930's to build their insectary to grow the black scale parasite, Metaphycus helvolus (Compere) for control of Saissettia oleae (Oliver). In 1961, the Fillmore Insectary started growing the "Golden Chalcid" Aphytis melinus DeBach, for control of California red scale.Augmentative releases of these beneficials has been the basis of its very successful pest management programs. Reliance on biological control has led to control of ten species of insects that are major pests of citrus in other districts. Limited pesticide treatments, such as for ant control, are made in ways that conserve natural enemy complexes associated with all pests of citrus. Thus a large group of farmers with total of 9,400 acres has kept average pesticide treatments below one application per acre per year for over 50 years. One might ask why the existing commercial insectaries are not producing more new and varied biological controls on contract or for sale. If you think about it, the vast array of natural enemy complexes are not being marketed, because there is not enough demand. Needs are often very specific and within limited time frames. Losses from variable weather patterns affecting the window for releases, shipping and now the growing administrative costs of compliance with regulatory agencies over the transport of biological organisms not to mention the capital, supply and human resource development costs associated with developing a new mass-rearing system result in little if any profitability. When you consider that after all of this investment, the organism is not-patentable and belongs to anybody who wants to buy it and piggyback on the original producers developmental efforts, it is no wonder that new organisms are not arriving in the marketplace the farmers would like.Farmer insectaries avoid many costs of commercial. insectaries. They give preferred service in timing releases. Specific strains most appropriate to the geographic region are produced. There are no marketing and distribution Costs. Combining insectary beneficials with monitoring by affiliated entomologists to maximize indigenous natural enemy complexes allows for maximum flexibility and minimum losses.In addition to the mass-rearing and monitoring resources that the growers can fund cooperatively, classical biological projects can also be organized most cost-effectively by cooperatives with technical assistance from universities. Governments and universities are not obtaining the needed funds to conduct these essential projects to meet demands of increasing numbers of exotic pests being spread around the world by travel and commerce. Even when governmentdoes acquire the money to research and import an exotic beneficial, there is never enough money to mass-produce and distribute them. The implementation of biological control on farms is up to individual growers working together. The small farmer-financed insectary can fulfill this need.

 

An example of how this might work would be with the classical biological control "biotype" obtained of the egg parasite Anagrus epos that attacks the variegated leafhopper. These parasites have been imported and colonized successfully by the University of California biological control specialists. Numerous releases have been made experimentally, but there is no money for wide distribution of these new parasites. If farmers wait for them to spread throughout the range of the host, it may take years.

 

A grower-owned insectary could easily obtain and produce this parasite and spread it among its members right away. Thus, biological control of this key pest can be achieved in a few years instead of a decade or more.Organizing- farmer-owned biological control insectaries is not a subject taught in agricultural schools in the U.S., nor is it effectively promoted by the agricultural extension services. Considerable effort and money is spent on monitoring pests and on propaganda describing pests and pesticides, but our educational and advisory institutions have ignored the development of informational materials and training in skills of insectary development and management, beneficial insect production systems and in how to best use beneficials in various production settings.

 

Although it is difficult to join together the several forces that are needed to begin such cooperative efforts, the time is right and the results promise to be long-lasting with increased profits going where they belong.., to the farmers. The technology is known and there are under-employed advocates trained in the science of biological control who would welcome the chance to practice under the leadership and financing of grower organizations.

 

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Diversity and Refugia Make Biological Pest Control Work

 

by Jan Dietrick

Published as The Insect Side, in Acres USA, September 1995, p 32-33

 

Once upon a time, alfalfa hay and pastures provided the permanent refuge areas that were home to a thousand or more species of beneficial insects. They migrated from the non-irrigated foothills and provided biological control in all vegetable and field crops. Alfalfa hay was the one irrigated crop that was never sprayed. No one sprayed alfalfa because the price was too low to sustain the cost of spraying.

 

Another source of diversity was cover crops that were planted for soil improvement, pollination and green manure. When production fields and orchards were sprayed from time to time, the natural enemies which were plentiful in the havens of alfalfa hay and cover crops migrated into the sprayed areas. At hay cutting time, insects and their beneficials were driven from cut fields restoring biological control in the previously sprayed market crops.

 

Resistance to pesticides did not develop in that arrangement, because pests not killed by the poisons were controlled by predators and parasites immigrating from the hay fields where pesticides were never used. Alfalfa was grown for crop rotation, soil improvement, and animal forage and had no economic threshold for pest damage. When resident weeds overtook the hay stand, the fields were rotated to market crops or were replanted. There were plenty of irrigated, unsprayed fields where predators, parasites, pollinators, and diseases of insects that served as antagonists to pest development worked together like they do in all diverse natural ecosystems.

 

The picture changed dramatically when the price of alfalfa increased to the point where it became worth spraying. This was followed by herbicides replacing cover crops. Cattle and sheep grazing on the foothills without irrigation destroyed even more insect havens. There was almost nothing growing or irrigated anymore that was not a market crop with an economic threshold for pesticide use. The increasing cost of land and water forced farmers to focus on the bottom-line by maximizing production using total chemical pesticide management. Increasing labor costs, development of effective but costly farm machinery using more energy, the marketing of more and more powerful synthetic pesticides, concentration on cheap petroleum-based fertilizer, all contributed to decreasing the diversity of plant, animal and microbial life in the soil and crop.

 

Large, single-crop farms replaced small family farms that had been successful be-cause they produced several crops. In addition, maximizing individual crop yields replaced the goal of optimizing total farm production costs. Breeding for higher yields and precision planting of more uniform plants eliminated even more natural diversity within a single crop, thereby increasing the chances of pest outbreaks.Into this uniform, monoculture type of production, we started introducing more exotic pests from foreign lands, because there is much more international commerce and travel than before. Government funding for foreign exploration to research natural enemies to immigrant pests, slowed to a virtual standstill. Less and less research was done to colonize new beneficial species to attack exotic pests, even though we have more immigrant pests that are difficult to keep out.

 

It evolved this way so that now, when a new pest invades a monoculture environment, farmers have no biological options. They have to spray. The poison destroys all existing beneficial organisms that provide biological control of all other pests. Minor secondary pests become major problems and lead to a dependence on the pesticide treadmill. Total chemical pest management breeds resistance to all pesticides and disastrous consequences of "super pests" such as resistant sweet potato whitefly, leafminers, aphids, etc. Resistant medfly may become the next disaster when eradication fails and this pest becomes firmly established.

 

Individual farmers can overcome pesticide resistance using the principle of diversity. By diversifying crop selection, cover cropping and providing permanent refuges for natural enemies, immigrating pests and their sets of beneficial natural enemies, including pollinators, can be kept on their farms. Relatively small areas on the farm can be cost-effectively planted and managed to provide a favorable environment for beneficial insects and their hosts. Edges and corners of fields can be utilized along with limited use of border strips of diverse species of cover crops. These unsprayed cover crop plantings, along with resident weeds, are more than just shade and ground cover. They provide nectar, pollen, and plant material that a tracts many diverse sets of plant-feeding insects which are the prey for many, many more sets of predators and parasites.

 

Today, managing this resource on your farm has actually become a necessity. Augmentation of insectary-reared beneficials in market crops are more cost-effective on farms with diversity. You can manage with lower numbers of these key species when you are supplementing the resources of hundreds of species of natural enemies for which there is no other source except natural diversity on the farm.

 

REFUGIA

 

In a world where all irrigated crops are grown for market, there is no nonsprayed, permanent sanctuary for insects anymore. The majority of all crops are grown for market and therefore managed totally with chemicals. Since there are no permanent unsprayed irrigated crops to sustain natural biological control, when chemically resistant and immigrant pests come in, farmers have no choice but to keep spraying.

 

Farmers interested in a transition from conventional pesticides to alternative biological control must create some diversity and provide refugia that keep beneficials on the land. Planting refugia is necessary for biological control on farms coming out of monoculture cropping and reliance on chemical pesticides. Refugia can be used to protect individual fields as well as the whole farm.

 

Refugia help keep migrating insects out of the market crops, generating larger numbers of predators at no cost (or damage) to market produce quality. Refugia can buffer the impact of insect migrations from the foothills when native plants mature and dry up. Refugia are not market crops and therefore no limits are placed upon heavy populations of plant-feeding insect pests feeding on those plants. The plant-feeding insects are valuable prey for growing predators and parasites, such as ladybugs, lacewings, insect eating spiders, etc. These predators will forage beyond the refugia, searching for pests in the market crops thus preventing or stopping pest invasion when it first starts.

 

Many of the interferences to biological control such as pesticide drift, honeydew-seeking ants, dust and adverse climate effects can be managed cost-effectively by planting border strips of cover crop plants that affect temperature and humidity, initiating micro-climates favorable to the survival of natural enemies. Increased numbers and diversity of plants can shade out ever-expanding ant nesting sites and provide a complexity of insect life that increases populations of natural enemies.

 

Alternate prey are needed as food for natural enemies. This important resource of a complexity of plant-feeding prey living on resident weeds and cover crop plants attracts and feeds predators and parasites of pests and keeps them on the farm. Most carnivores must be supplied with enough prey or alternate food sources; otherwise, unless they go into diapause, they will leave in search of food. It is better to increase prey in sacrificial refugia on the farm rather than sustain them by taking damage on the market crops.

 

It is important to consider the pest-inducing effects of ants, dust and radiation, especially at the interface of irrigated farms with dusty field roads and open wild areas. Dust builds up on plants in between infrequent rainfall. Overhead sprinkler irrigation applied when needed can clean plants of dust. Conventionally sprayed plants look more beautiful, especially immediately following sprays. An alternative to poisons is water washing that may be advised in some situations to satisfy aesthetic needs. (It makes more sense than using pesticides to clean the plants!)

 

The intensity and duration of solar radiation on outside rows of market crops is implicated in physiological susceptibility of plants to pest populations. Spider-mite populations increase on the hot outside row of plants due to exposure to radiation effects. Cover crop planting and mulching along such borders reduces these pest-inducing radiation effects sufficiently to control many pests and improve fruit quality on these outside rows.

 

At the same time as cover crops provide prey for increased numbers of natural enemies, the decomposition from mulching of cover crop mowings (sheet composting) forms other biological systems that breakdown plant and animal life into food chains of alternate prey for soil pests and plant diseases. For example, ephedrid fly maggots that decompose plant material are prey for rover and ground beetles that may contribute to biological control of minor insect pests, such as fleabeetle rootworms, wireworoms, black vine weevils and other pests that over-winter in the soil. These systems are part of the complexity of natural enemies that we see working on healthy organic farms that regulate excessive pest population increases.

 

Trapping affects increases in such plant-feeding pests which are food for diverse populations of spiders and other predators. The overall effect of managed refugia for enhancement of biological control increases field insectary production of thousands of species of natural organisms interacting to improve efficiency of biological control in the whole agroecosystem. These smart choices of creating refugia can be applied around greenhouses just as well as on production farms and orchards.

 

Augmentation with some of the key beneficial organisms that are grown commercially becomes very cost-effective on farms where diversity is already present. The refugia can be managed and used at very low cost (compared to the rising cost of failing conventional total chemical management) attracting and trapping migrating pests and providing ideal hospitality to a well-balanced natural enemy system of sustainable biological control.

 

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Integrated Pest Control - Theory And Practice

Everett J. Dietrick, 1976

 

The purpose of this paper is to define the practice of integrated pest control. For this definition I have drawn largely from papers and reviews, and from conversations with insect ecologists of the Department of Biological Control of the University of California, where I was employed for 15 years. I have had years of experience in practical application of integrated pest control techniques in the field, in my work as a professional insect ecologist representing Rincon-Vitova Insectaries, producers of beneficial insects. My experience also includes association with several well-established supervised control entomologists who are independent of any company affiliations: we are supervising integrated pest control programs on cotton, citrus, apples, pears, tomatoes, corn, potatoes, avocados, olives, grapes, eggplant, lettuce, geraniums, stone fruits and nuts, artichokes, strawberries, and others.

 

The increasing ineffectiveness of chemical pesticides and the farmer's narrowing profit margins have stimulated the search for more economic regulation of pests. One of these programs is integrated pest control that is, an insect population management system utilizing all suitable control procedures and agricultural production techniques, blending them into a coordinated pattern aimed at profitable production of quality products.

 

The philosophy of integrated pest control is based upon (1) the principles of applied ecology, (2) the recognition that 10000 mortality of all pests is not required, and (3) avoidance of disruptive chemicals. Since this philosophy of pest control is more of a system of principles for guidance than a set of rules in a fixed program, it requires more than the usual judgment to make it work on the farm.Integrated pest control is based on the principles of applied ecology. Whatever is done in any field situation is always founded, as far as possible, upon full knowledge of the ecology of the pests. In practice, this is attainable only by continuous sampling of the insects in all parts of the fields where integrated control programs are being applied. By this policy of watching the fields much more closely than usual, all the natural control factors can be exploited. Implementing this policy requires the services of a professional insect ecologist under contract to the farmer. This specialist in integrated pest control is the leader of a team that samples the fields, analyzing the total interacting complex of organisms, including the pests and their biological controls, and the effects of all of the agricultural practices and industrial activities of man. This dynamic consideration of the fields takes into account the evolving patterns of plant growth, seasonal developments, and the ever-changing populations of organisms associated with them. Emphasis is always on the developing insect population levels and the predictions as to the course that the pest populations will take.The supervising insect ecologist implements successful pest management in the fields by applying any or all practical cultural and biological practices known to suppress the pests. To attain a favorable balance in a field, it is necessary to attract, augment, and conserve all possible numbers of beneficial predators, parasites, and disease organisms in the fields. Even low numbers of insectary-grown and/or field harvested beneficial insects can be colonized.

 

Best results from integrated pest control are obtained when effective natural enemies of most target pests are present in the complex of organisms. Crop rotations to alfalfa, grains, and pasture, along with planned cover crops, bring greater plant diversity to a farming area. This diversity of plants brings greater diversity in both host and prey species, and provides nectar, pollen, and alternate host organisms as food for predators and parasites. Alfalfa, grains, and pasture grasses are normally under such satisfactory biological control that they usually require very little control other than cultural management. Such management programs in alfalfa, using strip harvesting techniques, aids in preventing sudden emigration of pests at cutting time. With less disruptive action to pests and their biological controls, there is greater stability in population interaction, and less chance for one species to dominate and cause damage. Different natural enemies have different efficiency levels related to pest population densities; the above environmental manipulations help provide a complete complex of predators and parasites, at a very low cost.

 

Field harvesting techniques can selectively remove portions of pest populations and collect many predators, parasites, and disease organisms for use in augmenting the natural controls in other fields. Releases of this material, along with colonizations of insectary-grown beneficial insects, can help bring the field into a favorable balance in time to prevent economic losses.

 

Every pest spot in a field that is controlled biologically adds to the total number of predators in the field; every biologically controlled field grows more predators for the nearby fields and the agricultural area. The less you spray, the less you need to spray. This complex of beneficial insects is a natural resource that the farmer must protect and conserve by applying pesticides only when absolutely necessary to protect the crop. For certain pests there are no immediate prospects for development of effective pest suppression techniques. Then pest populations increase beyond tolerable limits and there is no predictable chance of obtaining a favorable balance, the crop can always be sprayed.

 

This leads us to the second principle of integrated pest control; a recognition that l00% mortality of all pests is not required to prevent economic losses. This may seem elementary, but society has been brainwashed into believing that "the only good bug is a dead bug"; it is important to point out that insects, mites, weeds, etc. are pests only when they affect our way of life beyond tolerable limits, It is essential to the concept of integrated control that we live with a few pests in order to obtain and retain a favorable balance.

 

Strict standardization procedures that do not necessarily give the consumer food of better quality or taste may force the farmer to spray for light infestations of a pest. Often any plant damage that might occur would not be harmful to the crop, except perhaps in appearance. Plants can tolerate low populations of aphids, thrips, and mites with no intolerable damage affecting profitable production of the crop. Instead of spraying, the insect ecologist uses these minor pests as food in colonizing additional insectary-grown or field harvested predators. The challenge for the future is to devise ways to grow and or field harvest sufficient beneficial insects and apply them to the fields by mechanical means; in this way, biological control could be better implemented and guaranteed, and many more fields could be saved from pesticides.

 

The third principle of integrated pest control is the avoidance of disruptive chemicals. Not all pesticides have adverse effects, and certain dosages of conventional pesticides are less disruptive to the existing biological control. Backup sprays are applied when necessary, but of a kind and in a manner least disruptive. Integrated pest control seeks to suppress target pest populations below tolerable damage levels without destroying their biological controls. The professional insect ecologist must know how to use pesticides in this way in given situations. However, because of the polluting side effects of too much pesticide in the environment, it is even more important that he know when and where not to use them.

 

There is not time to dwell on all the pest control problems that have developed as a result of complete reliance on chemicals; a short list would include target pest resistance to pesticides, target pest resurgence following treatments, secondary pest outbreaks, pesticide residue problems in the crop, the soil, or drift to nearby areas, or runoff to streams and drainage, and destruction of pollinators and other forms of life beneficial to man. In many instances these side effects have created havoc, and the undesirable results have more than off-set any original benefits. It is becoming more and more difficult to kill the target pests economically.

 

 

One often-underestimated side problem is the drift of pesticide residues onto nearby crop areas and the widespread effect of destroying favorable biological balances. Searching predators and parasites moving over the plants in search of prey are exposed to more residue, and are killed in greater numbers than the more sedentary pests. This uncontrollable drift creates new pest situations in nearby fields, that in turn require treatment: the problem is spread further and further. Such drift effects have triggered pest outbreaks over large areas and destroyed many beneficial insects. The more you spray the more you need to spray.

 

The cost of chemical pest control programs is high when all of these side effects begin to interact. The crops may be saved, but at great cost to society and the farmer (who is stuck with the pesticide bills). The real measure of success in farming is in the profits; the real problem that causes the farmer to look for new answers to pest control is the spiraling cost of repeated and ineffective treatments. This search for new answers has forced farmers and entomologists to modify their pest control practices, so as to avoid disruptive chemicals as much as possible.

 

How effective is integrated pest control in practice? Experience has shown that this philosophy, when practiced on the farm by competent professional insect ecologist, is the only pest management system dynamic enough to solve the problems and keep up with the changing agricultural problems of the future.The farmer must willingly support a team effort to carry out practical application of integrated pest control. The leader is the insect ecologist, a highly trained specialist who utilizes materials and techniques as complicated as those used by the pharmacist or veterinarian. New, more sophisticated integrated pest control programs of the future will be implemented by these professional insect ecologists. The backup part of the integrated pest control team is the insectary, which grows the predators and parasites, and field harvests other beneficial insects, for use in applying positive biological and environmental pest suppression. Other members of the team are the researchers, specializing in long-term ecological studies and development of integrated pest control techniques. Laboratory research specialists on physiology and behavior can discover much to aid in interpretation of data, but only studies in the fields will reveal the true interplay of all the complex ecological factors. The usual fragmentary short-term experiments, so common in pesticide evaluations, are more than vulnerable to error, when considered in the long-term ecological sense.

 

It is important to understand that valid scientific discovery can result from careful observations and recordings of recurring natural happenings. In other words, scientific proof can be obtained from a sequence of experiments or experiences. History will repeat itself, provided the same combination of effective conditions recurs. In applying integrated pest control, the insect ecologist frequently samples and assesses the fields in his care, constituting a continuous experiment in applied ecology not duplicated at research level. This experiment is carried out in many different field situations, throughout the season, and often over many years on the same farm. What better proof is there of the success of integrated pest control than the practical experience of profitable production of quality products?

 

Research specialists in integrated pest control must work closely with the insect ecologist, who is the foreman in charge of pest control. Since a multifactored environment is not easy to understand, the researcher can aid in interpreting the experience of the applied worker. At the same time, the insect ecologist can provide assistance to the researchers economically, gathering samples, etc., because he lives in the area of the field experiment. In this way the practical limitations of time and money can be somewhat overcome, and the work of solving the pressing problem of pest control can continue.The commercial pest control applicators and the producers of chemicals and other pest control products will continue to make an important contribution. The pesticide companies will make new products to answer the needs of integrated pest control, because it is the more selective target pesticides that are least disruptive that the farmers will buy.

 

Active and aggressive educational programs supporting the ecological approach to pest control can help separate fact from fiction regarding integrated pest management. General recommendations to farmers should be flexible, to allow time for alternative integrated pest control techniques to be exploited. Adjustable economic injury levels, including the assessment of beneficial organisms and suggestions for use of selective pesticides, are advisable.

 

The combined efforts of all members of the integrated pest control team are needed to insure successful and profitable production of sufficient food and fiber for the future. Successful pest control is relative, but in the final analysis it is measured in the economic sense. High costs of ineffective pesticide programs and their ultimate effects on food and fiber prices concerns farmer and consumer alike. There is no question of the success of integrated control in the minds of farmers who have changed their philosophy of pest control and are "suddenly" not paying excessive pesticide bills. The first year or two of successful integrated pest control is often attributed to "luck" or a "good year" by critics of such programs. After several years of economical pest management with little or no spray bills, the farmer eagerly support their insect ecologist and the insectary that supports him. As food supplies become shorter in the coming decades, and as consumers become more conscious of high food costs and toxic residues in foods and less conscious of appearance only, the artificial standards that pesticides depend on will be relaxed. More sophisticated and safer processing of farm products will be developed to insure removal of insect parts, with the result that the consumer will have bug-free as well as toxicant-free products.

 

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Biological Control: An Ecological Approach To Pest Management For Farms, Ranches, & Gardens

 

Everett Dietrick, about 1990

 

Biological control is nature's way of regulating insect pest populations. Damage due to plant-feeding insects and mites can best be prevented when sufficient predatory and parasitic organisms keep the pests reduced to tolerable or "economic" levels (that level below which the pest does no damage to the plant). These natural enemies have been regulating plant-feeding pests since ancient times. Today, more than ever, we need to exploit their usefulness in the family garden as well as on the modern farm.What is biological control?Insects have been controlled by other insects, and diseases of insects, since the beginning of time. For our purposes here, we define beneficial insects as those insects beneficial to man in his efforts to harvest nature; and we define pest insects as those insects which are harmful to plants and animals. Certain beneficial insects called predators feed on several different kinds of prey, and they require multiple prey individuals in order to complete their development to the adult stage. Parasites, on the other hand, usually complete their development on or inside a single host individual (a host is that insect on or in which the parasite feeds and grows). Predators and parasites do not become pests themselves, since these beneficial insects are programmed by nature to adjust their own populations to fit those of the pests. This is all part of the balance of nature which regulates pest populations all over the world. In the natural scheme of things, each insect species has its own population range set up by mother nature. If one species should increase its numbers above that range, the insects which prey on that particular species (or parasitize it) will increase their own populations accordingly, since there is so much more food available. The carnivorous beneficial insects devour the pests, thus increasing their own populations at the expense of the pest populations. When the pest population has been brought down to its normal range in nature, the reduced amount of food will cause the predatory and parasitic populations to be reduced again (through starvation or lack of hosts); thus, nature is brought back into a satisfactory balance.

 

Augmentation of this natural control, or the balance of nature, is also called biological control. Biological control is merely another name for aiding the balance of nature, by adding beneficial insects to the fields to help control the pest insects. Entomologists at Rincon-Vitova Insectaries have developed pest management programs that exploit this natural control through habitat management (farming & gardening practices) and colonizations of beneficial predators and parasites. Our programs are designed to help biological control of pests on farms, ranches, and gardens.Pests are only pests when they occur in intolerable numbers!

 

Biological control does not mean eradication of the pest populations. It is, rather, a balance of insects, both good and bad, that keeps the pests from expanding to dangerous levels. This concept is essential to the understanding and implementation of successful biological control. It is only the intolerable numbers of surplus pest individuals causing intolerable damage to plants that are truly pests. The balance between good bugs and bad bugs is never static, but changes constantly, and is never equally distributed; some areas or branches are more heavily infested with pests than certain others; on the other hand, in certain areas of the garden there are reservoirs of beneficial predators and parasites in greater concentration. Pests will concentrate in spots or on branches that protrude, etc.; they may concentrate in a spot where some factor has previously eliminated biological control (ants protecting aphids, road dust interfering with predation, pesticide residues killing beneficial insects, winds carrying in pests from neighboring fields, etc.). Little pest fires like this can rapidly turn into holocausts, wiping out an entire garden, unless there is a complex of beneficial insects present to suppress them. The aim of biological control, therefore, is to create the best possible overall balance of beneficial insects in the garden, so that these little pest flareups can be quickly put out before they start to spread. Successful biological control can be achieved when there is a wide variety of all kinds of insects in the garden, both good and bad ones.

 

Low populations of some of the less destructive pest insects are necessary in a garden, for they serve as food to keep the beneficial insects healthy and in the garden. Another great source of food for the beneficial insects are the pollenators and other incidental species which are attracted to decomposing organic wastes (leaves, prunings, animal manures, etc.). If there were no pest or decomposing insects to feed on, the beneficial insects would either die off or leave the garden in search of food. Again, the idea here is one of a balance of insects. When this balance is established in the garden, the insects will then take over the job os regulating their own populations.Good cultural practices are essential to biological control.

 

This overall balance in the garden can best be established with the creation of a suitable habitat for the insects in the garden, both the pests and the beneficial insects. One of the most interesting aspects of biological control is the beneficial insect habit of being attracted to a suitable physical habitat, and then turning to attack their hosts present in that habitat. The insects, therefore, need a habitat in which they can thrive, or many of them will die off or leave the garden. Implementation of good cultural practices to create a good habitat is essential to a successful biological control program.The key to creating a good habitat for the insects is establishing a diversity of nature in the garden. Nature is based on diversity, and it is a complex of interacting factors which favors successful biological control. It is very rare that a single beneficial insect species ever gives complete control of a certain pest; rather, it is the interaction of several different predator and parasite species that gives effective overall pest regulation. For example, if one set of predators and parasites can destroy a certain percentage of pest eggs, another set will more easily be able to reduce the remaining population of adults on which they feed. Thus, the idea is to attract and retain as many kinds of beneficial insects as possible in the garden, as a general buffer against pests. This can best be accomplished through a diversity of plants. Different kinds of plants attract different kinds of insects, resulting in a biological balance in the garden. Plant as wide a variety of plants as possible, and plant them in small blocks. Plant flowering plants as well as vegetables and fruit trees; they will not only make the garden more beautiful, but will also help create a biological balance by providing pollen and nectar for the beneficial insects. Strong, healthy plants can outgrow many potentially serious pest situations; humus-forming mulch can help control weeds and provide additional plant food, while helping retain moisture in the ground. Limited numbers of natural grasses and even weeds can provide a protective niche for predators and parasites, providing host insects, nectar, pollen, and sources of water in dews and moist organic litter on the soil surface. Beneficial insects are small, with a high surface-to-volume ratio, and they lose their water content quickly in unfavorable environments. In order to survive, they must be able to replenish their water content. In general, most insects need a drink of water each day; if water is not provided in the habitat, predators may turn to the plants as a source of moisture, and thus become minor pests themselves. It is very important, therefore, that we provide free water in the garden for the beneficial insects.In addition to diversifying plantings, try to keep a sequence of plants planted in the garden at all times, even if this means planting green manures or sod grasses for the compost heap. Crop rotation can be accomplished in the garden just as it is on the farm, only on a smaller scale, especially if the plantings are in permanent beds with permanent walk areas. This sequence of plantings (which is just a matter of planting whatever can be grown in each season throughout the year) will retain the complex of insects in the garden. When the garden is abandoned during the winter, the insects will overwinter in the plant refuse. Surplus plant residues, litter, and other garden waste products should be rapidly composted to remove them as potential habitats for the pests. This composting helps provide the decomposing organisms which are a valuable alternate food source for the beneficial insects. A constantly active garden will retain a constantly active complex of insects, ready at all times to help control garden pests.All in all, the more diversity the better. The more plants in a garden, the more kinds of insects will reside there. The more kinds of insects in a garden, the better the biological balance will be. The many varieties of insects will help control each other; and the beneficial ins will remain there even when pest populations are low, because there will be pollen, nectar, alternate hosts, and sources of water for the feed on until they are needed again to help suppress the pests. In this way, an overall balance is created in the garden, providing a su habitat for all insects, and helping to give better pest control. WARNING - Ant control is important! Ants protect aphids and other hoi producing pests from their natural enemies by destroying them and otherwise disturbing their control effects.Release of insectary-grown beneficial insects helps biological control.

 

Biological control can be augmented by colonizations of insectary-grown predators and parasites. The addition of even low numbers of beneficial insects can tip the balance of nature in favor of the good insects. The insectary can guarantee the presence of certain beneficial species through periodic releases, thus improving the ratio of good insects to pests. The battle of the bugs is won when there are sufficient predators and parasites present to destroy the majority of pests. Thus, the number of beneficial insects required depends completely on natural complex present in the garden and the extent of the pest problem. The more beneficial insects present in the garden, the better pest control will be. On many occasions, there is an insufficient number of natural enemies present for effective pest control. Therefor releases of these insects into the garden will augment the populations already there, and give more effective pest control by helping to establish a better balance of insects in the garden. In order to cover all potential pest situations, it is advisable to make a series of re of beneficial insects, rather than just a single large release.

 

What does Rincon-Vitova, Inc. offer for biological control?Trichogramma wasps: these very tiny wasps, which are harmless to people, attack all kinds of moth and butterfly eggs. They lay their eggs in the eggs of the moth or butterfly. The immature Trichogramma devour the moth egg and hatch into parasites; in this way, more Trichogramma parasites are grown each generation. It is important to start colonizations as soon as there are any host eggs present. Black-light insect traps are good indicators for the presence of egg-laying moths. Trichogramma develop more quickly in summer than in winter. A generation takes 10 days at 80 degrees. Maximum kill of pest eggs can prevent worms from hatching. It is advisable to colonize this egg killer frequently to prevent as many worms as possible from hatching. Trichogramma recommendations are as follows:Vegetable and Flower Gardens -For a moderate sized garden, 15,000 Trichogramma is usually sufficient for each release. Make three releases two weeks apart, preferably starting when the garden is growing well in the spring. Additional releases should be made when pest problems are severe.Deciduous Fruit and Nut Orchards -Release 15,000 to the acre as soon as the leaves are fully emerged and repeat this colonization for five weeks. This will cover the spring flights of most moths that enter the orchards. Some varieties of fruit have more severe pest situations and therefore larger numbers released will give better results. We cannot recommend an exact number because of the difference in size of trees and the degree of infestation. However, we do know that Trichogramma work if good judgment is used.Ornamentals, Citrus, Avocados -The above recommendations hold for non-deciduous trees and bushes except that the timing of the releases should begin in early summer when moth activity speeds up. Try to match your releases to the flights of the moths and butterflies that lay the eggs.Alfalfa, Cotton, Sorghum, Field Corn, Grains -All are infested by various worm pests. Weekly releases of 2,000 to 5,000 Trichogramma per acre starting with the first warm weather in early summer have been found to help biological control.Green lacewings (Chrysopa carnea): these small, pale green insects have gained national attention as all-purpose predators of insects and mites. Lacewings are an effective natural enemy of aphids, mites, whiteflies, mealybugs, leafhoppers, thrips, all sorts of moth and butterfly eggs, and caterpillars. The larva is known as the "aphid lion" because of its voracious appetite for aphids. Just as Trichogramma is the universal egg parasite, lacewings are the "broad-spectrum" predators that are useful in biological control of nearly every crop and pest situation. It is common sense to augment this beneficial predator wherever and whenever possible in all pest situations in all crops.The ladybugs (Hippodamia convergens) that are field collected in the hibernation sites and sold by other insectaries, fly away from the yard where they are needed more often than not.

 

Rincon-Vitova has developed a program of conditioning the diapausing ladybugs so as to wake their reproductive activity. Rincon-Vitova ladybugs are pre-fed and conditioned so they are ready to feed and lay eggs in the garden when they encounter aphids. It is important to point out that ladybugs are dependent upon aphids to trigger their egg-laying response, whereas lacewings are released as hatching eggs that will eat any pest they encounter. Lacewings go right to work on the widest spectrum of pests without conditioning.

 

Our recommendations for using lacewings are: minimum order of approximately 3 to 5 thousand for a small garden. These tiny larvae should be released in as many pest situations as possible so as to "seed" these important predators into the garden early in the spring. Best timing is with the first aphids of the year. However, lacewings may be released successfully at any time of the year. Augmentation releases made in all pest situations as they develop gives maximum biological control. Lacewings control orchard pests equally as well. Eggs and larvae can be placed where tree branches touch the ground or in the crotch of the tree, or by being salted onto leaves. Larvae are extremely secretive and hold on to plant surfaces.

 

Fly parasites: these tiny parasitic wasps are released for fly control in breeding sites on poultry and egg farms, dairy and beef cattle feed lots, and backyard horse stalls and other domestic animal manure accumulations. The parasites attack flies by laying their eggs in the larvae and pupae. The eggs hatch inside the flies, and the parasites eat the immature flies, then emerge as adult parasites. They cannot become pests themselves, since they can only survive by finding other immature flies on which to lay their eggs.Costs of these biological control insects varies according to the severity of the problem; there is no set amount to purchase in order to achieve control. See our accompanying brochures for some suggestions on amounts needed. In addition to the insects listed above, Rincon-Vitova Insectaries also market several other kinds of beneficial insects for use in controlling farm, ranch, and garden pests.

 

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