Biological control with beneficial insects makes dollars and sense, even in chemically sprayed cotton fields. Beneficial insects growing wildly in fields are one of nature's great free sources of pest control, a resource to augment and nurture, not squander or slug into oblivion under a pesticidal rain. When properly managed, biological control organisms can be a valuable part of your cotton profit team.
Costs of sprays, scheduling sprays when workers are not present, public and worker liability risks, even insurance costs, may be reduced when biological control organisms assume more pest management chores in your cotton fields. Residue and resistance problems, particularly whiteflies and leafminers, are avoidable when pest-fighting biological control armies are integrated into your cotton pest defense system.
Fifty to 75 percent pest control cost savings have been reported within the first two years by cotton growers transitioning from chemical farming to a more sustainable ecological approach utilizing beneficial organisms. Even gaining a mere few weeks delay in the onset of spraying by making early releases of beneficials can yield dramatic monetary gains, with natural biological control substituting for weeks of pesticide inputs. As if this were not enough, there are also public relations benefits from using this "green", environmentally-friendly alternative to conventional chemical control.
COTTON BIOLOGICAL CONTROL
Unsprayed cotton fields host an army of several million beneficial arthropods per acre, a valuable free source of natural pest control best nurtured, but all too easily and often destroyed by harsh pesticide regimens. Bollworms, loopers, aphids, whiteflies, leafminers, spider mites and other potential pests seldom pose major problems in cotton fields where the indigenous pest-fighting natural enemies are preserved.
Among the hundreds of beneficial species commonly devouring cotton pests are green and brown lacewings, pirate bugs, big-eyed bugs, assassin bugs, damsel bugs, spined soldier beetles, Staphylinid rove beetles, Carabid ground beetles, Collops beetles, lady beetles, six-spotted thrips, Tachinid flies, Phytoseiid mites, spiders and several dozen parasitic wasp species, including Trichogramma.
Two of the 50 potential cotton pests, the pink bollworm and boll weevil, most consistently elude these hungry cotton field predators and parasites. Both pinkie and the boll weevil feed internally on squares and bolls, thereby escaping enough of the common cotton field beneficials to pose chronic problems.
NEW PINK BOLLWORM EGG PARASITE
Rincon-Vitova is addressing the pink bollworm problem by introducing a new natural enemy, Trichogrammatoidea bactrae, an Australian import that destroys moth eggs before pinkie caterpillars hatch out and burrow into the hidden safety of their cotton boll feeding niche. Rincon's entomologists are excited about this new natural enemy, which turns pinkie's white eggs black, because mated females produce mostly new pest-egg-destroying females. Field studies in Brazil [Entomophaga 1987. 32(3):241-248] show that a related Trichogrammatoidea species teams up with other parasitoids to provide more than 50% caterpillar egg parasitism; with pirate bugs, big-eyed bugs, spiders and other predators in the natural enemy complex adding another 45% moth egg destruction, total egg destruction is 95.5%.
Few pesticides can match the 95+ percent pest egg destruction potential of the natural enemy complex -- indeed, pests like pinkie lay many eggs so to insure that a few individuals survive to perpetuate the species in this tough bug-eats-bug natural environment. The objective of adding new beneficials like Trichogrammatoidea bactrae to the cotton agroecosystem is strengthening the natural enemy complex, and creating an ecosystem where predator and prey (pest) are in better balance.
Neither Trichogrammatoidea bactrae nor any other beneficial species sold by Rincon-Vitova Insectaries is intended to be used as a pesticide for quick insect kill. Trichogrammatoidea bactrae, Trichogramma pretiosum, green lacewings, predatory mites and other Rincon-Vitova beneficials need to be integrated into agroecosystems, and nurtured into reproducing in the field. Releases of Rincon-Vitova's biological control organisms are intended to augment existing natural enemies, thereby tipping the balance of nature towards more biological pest control.
Harnessing and working in harmony with ecological processes to grow biological control organisms in cotton fields is a totally different process from chemical pesticide use. Creating sustainable biological control in cotton requires a change in thinking, as the rules are very different from chemical pest control. Even economic thresholds for pesticide treatments change when cotton fields are teeming with biological control organisms. When beneficials are on patrol in cotton fields, higher pest levels can be tolerated for longer periods of time without pesticide use, which translates into immediate bottom line pest control cost savings.
Rincon-Vitova's beneficial insects (all natural, none genetically engineered) are small pest-fighting farm animals, not pesticides. The state of Texas agrees that beneficial insects are farm animals, and, like cattle and pigs, exempts beneficial insects (as farm animals) from state sales tax. We oppose government regulatory agency expenditures of taxpayer monies (e.g. Cal-EPA) to regulate these tiny pest-eating farm animals as toxic chemical pesticides subject to the same costly regulatory policing policies as the toxic chemicals that brought on the current environmental crisis and consumer distrust of agriculture -- beneficial insects are part of the solution, not the problem.
When combined with sustainable cotton growing practices to encourage predators and parasites, periodic early season releases to establish Trichogrammatoidea bactrae, and inoculative releases of other Rincon-Vitova beneficials, can be cost effective, at least delaying the onset of costly chemical spray programs. Trichogrammatoidea bactrae and other beneficials are compatible with "soft pesticides" like BTs (e.g. Dipel, Javelin), sterile male releases and pheromone mating disruption (e.g. Attract 'n Kill and NoMate), making them good additions to integrated pest management (IPM) programs.
Rincon-Vitova Insectaries invites interested cotton growers and their PCAs to participate with us in evaluating the addition of Trichogrammatoidea bactrae to the cotton field natural enemy team against pinkie. This generalist beneficial insect is available to any cotton farmer. However, advance orders are required, as we are limiting production of this perishable living product (T. bactrae), and will not have the capacity to accept most last minute orders.
TRANSITIONS TO BIOCONTROL MADE EASIER
Rincon-Vitova tries to make the transition from heavy reliance upon pesticides to sustainable biological control as smooth as possible by continually collecting new strains of beneficials from heavily sprayed agroecosystems. Though we do not specifically test natural enemies for ability to withstand chemical sprays, we believe that some of our insects, particularly our green lacewings, great all-around predators, have been successful in transition situations due in part to this hardiness and ability to withstand some chemical residues.
Ideally, releases of beneficials are started as early in the season as possible, when the first pests enter cotton fields or neighboring crops (e.g. alfalfa, grains, vegetables) preceding cotton. One of our most popular strategies is initially releasing small numbers of beneficials to colonize young cotton, and following up with a series of weekly releases to insure long-term establishment of pest-destroying natural enemies. Farming ecologically with biological control inputs gets easier each year, as a reservoir of natural enemies becomes established.
Where pesticides have not killed off the natural enemies, most potential pests go unnoticed, as they are so effectively squelched by resident beneficials. When predators and parasites are destroyed by spray programs or starved away by lack of prey, releasing Rincon-Vitova's green lacewings, Trichogramma and other beneficials helps restore the natural balances found in unsprayed agro-ecosystems. Early season releases of insectary-grown beneficials are the backbone of reestablishing biological control. It is like restocking the fish pond when one starts releasing beneficials to rescue natural-enemy-depleted farms from the pesticide treadmill.
Rincon-Vitova Insectaries started out rearing Trichogramma egg parasites for cotton growers in 1960, and currently rears several different Trichogramma species adapted to a variety of crops and caterpillar (worm) pests. Rincon's Trichogramma pretiosum attacks eggs of numerous cotton moths, including bollworms and leaf worms.
Limited quantities of the tiny lady beetle Delphastus pusillus, a voracious predator of sweetpotato and poinsettia whiteflies, can also be inoculated into cotton fields. We advise placing orders well in advance, and setting aside unsprayed crop refuges to allow the small available inoculative quantities of Delphastus to reproduce and become a significant whitefly fighting force.
General predators such as lady beetles and green lacewings are available to help in early season aphid control -- these same insects help defeat spider mites after aphids come under biological control. Late-season biological control of worms (caterpillars) is an added benefit of holding off on early-season pesticides and allowing small early-season populations of beneficials to multiply into large mid- to late-season pest-fighting armies.
FREE SOURCES OF BENEFICIALS
Slight modifications in farming practices and ecological planting schemes can create cotton agro-ecosystems more closely emulating natural ecosystems, and promote the in-field production of millions (per acre) of voracious pest-eating beneficials at no additional cost to cotton growers. This free source of indigenous natural enemies, which would be prohibitively expensive to purchase, consistently controls sweetpotato whitefly and cotton aphids in unsprayed cotton agroecosystems.
Understanding the movement of natural enemies between crops is the key to unleashing this vast free source of biological pest control. Though there are differences among cotton growing areas, some general principles apply. Cotton field populations of dominant natural enemies are markedly increased when cotton agro-ecosystem diversity is increased, as compared with large cotton monocultures (one crop).
Biological control is also maximized when alternate crops act as field insectaries, growing large populations of pest-fighting predators and parasites that can migrate into cotton. Cotton interplanted with or growing adjacent to unsprayed alfalfa hay, sorghum, sunflower borders, vegetables, small grains, oil seed Brassicas, etc. attracts a wide variety of natural enemies, including lady beetles, green lacewings, Tachinid flies, big-eyed bugs, spiders, pirate bugs, predacious beetles and several genera of parasites that effectively control sweetpotato whitefly, bollworm, cotton aphids and other potential pests.
In integrated planting systems it is not unusual for minimally sprayed vegetable crops to produce more than four million parasites per acre, many of which migrate freely into adjacent crops, including cotton, and provide cheap (free) biological control. For example, a recent study of inoculative of Trichogramma on 667 acres of vegetables resulted in biological control on 3500 acres of adjacent cotton, with 60 to more than 90 percent parasitism of cotton caterpillars [Chinese Journal of Biological Control 1985. 1(4):2-7]. Experiences are similar in California and elsewhere when beneficials are allowed to grow (i.e. not killed off with broad-spectrum pesticides) in cropping systems overlapping cotton. From Texas to Africa to China and the former Soviet republics, Trichogramma releases directly into cotton produce similar dramatic results, provided growers switch from broad-spectrum pesticides that kill beneficials to IPM systems emphasizing softer materials like insect growth regulators, microbials, pheromone mating disruption etc.
Rincon-Vitova advises cotton growers to work closely with PCAs skilled in IPM methods such as beneficial insect releases, mating disruption, selective pesticides easy on beneficials, and spot spraying. If it is necessary to knock runaway pest populations down to levels that small populations of newly-introduced beneficials can easily mop up, use least-toxic, low-residual spray materials. The goal of spraying (selective use of pesticides least toxic to beneficials) is lowering pest populations to tolerable levels, not pest eradication. Low pest populations and innocuous alternate prey are necessary to feed biological control organisms. Without prey, predators and parasites are scarce. Hence, a few minor cotton pest situations must develop and be tolerated, in order to obtain and maintain a buffering natural enemy complex that subsequently controls major pest problems.
Planting legume, green manure, cover crop or alfalfa refugia (safe havens that are never sprayed) mimics the natural movement of beneficials from crop to crop. For example, alfalfa hay attracts aphids, mites and worms (few of which attack cotton) that nourish large pest-fighting populations of predators and parasites, a no-cost biological control army available to control pests in nearby cotton fields.
ALFALFA, KING OF THE INSECTARY CROPS
There are over 1,000 insect species in an average alfalfa field, the majority of which are beneficial, making alfalfa, along with sorghum, the main "insectary" crop in many agroecosystems. Agrichemical West magazine (July 1960) noted, "In Imperial Valley, alfalfa is the only large acreage crop grown throughout the year. Hence it is the principal reservoir of beneficial insects in that area. Conserving the beneficial insects therefore benefits growers of many other agricultural crops in the same region." A neglected lesson, unfortunately being relearned the hard way by Imperial Valley growers combating leafminers, whiteflies and other pests artificially created by pesticide destruction of biological control organisms in insectary crops like alfalfa.
In 1956, at the height of the University of California's statewide `war' against spotted alfalfa aphid, researchers discovered that strip farming alfalfa, instead of harvesting entire alfalfa acreages simultaneously, dramatically increased the number of biological control organisms, and reduced pest populations. Strip cutting (harvesting alternate strips or fields) stabilizes the alfalfa agro-ecosystem, with different-aged hay growths occurring simulatenously in the same or nearby fields.
When one strip is cut, alternate strips or fields are half grown, and fields and farms are never completely bare or without an alfalfa breeding refuge for beneficials. In the pioneering University of California studies, strip cut alfalfa had more than one million insect-eating spiders per acre, versus only 105,000 for regularly harvested alfalfa; 287,000 pest-destroying parasitic wasps, versus 70,000; 401,000 predatory big-eyed bugs, versus 199,000; 205,000 lady beetle adults, versus 46,000; 232,000 lady beetle larvae, versus 11,000. "By exact count the strip-farmed field contained four times as many natural enemies, with only one-fourth the number of alfalfa pests," along with a ton more hay per acre and no need for insecticides, reported Agrichemical West (July 1960).
As the season advances, begin mowing alternate strips or fields when cover crops or alfalfa begin to bloom; cut half and let this start to grow back before mowing the alternates. Avoid broad-spectrum pesticides at all costs in early season for maximum production of predators and parasites. Harvesting alternate strips keeps plants producing predators and parasites throughout the season, forcing a steady migration of beneficials into nearby cotton. This "battle of the bugs" takes place without damage to cotton.
Alfalfa is also an excellent Lygus trap crop. Cutting an entire alfalfa field at one time forces Lygus bugs to fly into neighboring crops. Nearby uncut alfalfa as a trap crop eliminates the need to spray cotton for Lygus.
STRIP CROPS STOP BOLLWORM & BOLL WEEVIL
Strip cropping is better known as a soil and water conservation technique than as an integrated pest management (IPM) tool. Strip intercropping, as the practice might be more accurately termed, is "growing two or more crops simultaneously in different strips wide enough to permit independent cultivation but narrow enough for the crops to interact agronomically" (Francis, 1986).
"To be quite accurate," wrote Harold E. Tower and Harry H. Gardner (1946) in a USDA Farmers' Bulletin titled Strip Cropping for Conservation and Production, "strip cropping is not a single practice; it is a combination of good farming practices. Strip cropping employs crop rotations, contour cultivation, proper tillage, stubble mulching, cover cropping, and other practices. The strip-cropping system maintains soil fertility and often increases it, maintains the maximum amount of ground cover for the greatest possible portion of the year, provides for the growing of field crops in a systematic arrangement of strips or bands which serve as vegetative barriers to erosion and waste of soil, water, and fertilizer. These are the principal and clearest advantages of the practice -- or system. The principal disadvantage of the system is its newness to many farmers."
Good strip intercrops do not impale parasites on sticky hairs, and have abundant pollen and nectar to fuel the natural enemy fighting force. Cotton, corn, cowpea, sorghum, and Crotolaria are among the good strip crop candidates. Texas experiments show that Trichogramma pretiosum - an egg parasite of bollworm and other cotton caterpillars that Rincon-Vitova has been selling to cotton growers since 1960 - and many other parasites live several times longer and destroy more pests when cotton, weeds or other plants provide nectar. Borders of alfalfa, sorghum, sunflower, corn etc. can also be quite effective, particularly when flowering, silking etc. are timed to pest life cycles.
In 1935, Marcovitch (J. Econ. Entomol. 28:62-69) touted strip farming for increasing the effectiveness of cotton boll weevil parasites: "In planning the cropping system there can be no possible harm in arranging to have a forage or hay crop adjacent to the cotton field. In case a forage crop is used, cowpeas, with the ever-present cowpea pod weevil would undoubtedly bring about the presence of several important parasites. The early removal of the cowpeas for fodder would force the parasites to attack the boll weevil." Cutting fencerow weeds led to highest boll-weevil parasitism in adjoining areas. Other plants harboring boll-weevil parasites include dewberry, croton and amorpha.
In 1947, Lincoln and Isley (J. Econ. Entomol. 40(3):437-8), after studying decades of Arkansas bollworm outbreaks, found that "The bollworm infestations developed when no trap crop was available." Cotton fields near late silking corn escaped major damage, as "the ovipositing moths apparently transferred their attention from cotton to corn and little late infestation of cotton followed. In one instance where a small planting of late corn, less than 2 acres, was adjacent to a field of cotton of about 60 acres, the average number of eggs on fresh silk was over 200 to the ear. Many eggs were also scattered over these corn plants. In all 15 of these fields, corn was effective as a trap crop and the infestation of cotton declined sharply with the beginning of silking."
Strip or trap crops can be the breeding grounds for beneficial arthropod wildlife that migrates, is forced (e.g. by cutting) or transferred (by D-Vac suction collection) to nearby cotton.
PUTTING IT ALL TOGETHER
Maintaining biological control in cotton throughout the season is an ongoing process.
Rincon-Vitova encourages cotton growers to work closely with PCAs and IPM consultants to create on-farm insectaries to provide large armies of natural enemies, devise trap crops for key pests, conserve indigenous beneficial arthropod wildlife through judicious pest control solutions and inoculate fields with new natural enemies. Since not all cotton plants or parts of fields get pests at the same time, careful monitoring and sampling of the progress of biological controls is advised to identify "hot spots" for treatment with larger numbers of beneficials. The best PCAs can also adjust economic treatment thresholds upwards to take into account the fact that fields patrolled by armies of natural enemies can withstand higher pest populations without showing economic loss.
It takes from one to three years to make the transition and grow back the known sets of resident natural enemies for all pests of vegetable and field crops. But for many growers, it is worth the effort, as biological control systems based upon natural enemies are safe, permanent, economical pest control solutions that fit in well with sustainable farming systems based upon ecological principles.
Rincon-Vitova Insectaries customers on accounts are informed through periodic mailings of new beneficial species, some of which are so scarce that only very small quantities can initially be provided for inoculation. In addition, where demand is sufficient, we can on special request collect or obtain rarer natural enemies not normally available commercially.
Technical bulletins are available for all the beneficials that we sell. A quality control specialist works to insure that the best possible product is sent out. Nevertheless, sometimes shipments of fragile insects can arrive injured or otherwise not meet expectations. As we stand behind all product shipped, please feel free to contact us should you ever feel that there is a problem or that a replacement may be necessary.