Biocontrol Solutions for Vegetable Crops
PO Box 1555, Ventura, CA 93002
800-248-2847 * 805-643-5407 * fax 805-643-6267
Biological control with beneficial insects makes dollars and sense, especially on chemically sprayed farms where pesticide resistant pests require repeated sprayings for control. Costs for sprays, scheduling sprays when workers are not present, public and worker liability risks, possible residues in market crop, soil and ground water, even insurance costs, may be reduced when biological control organisms assume more pest management chores on the farm. Failure of pesticides resulting in a pesticide treadmill creates monster pests, particularly aphids, whiteflies and leafminers, which vector crop diseases.
Rincon-Vitova Insectaries, Inc. has a long history of solving these kinds of problems. Our philosophy of Integrated Predator/Parasite Management that fosters natural enemies can be the solution! Minor adjustments in the way we farm will provide nature's great free sources of biological pest control. Our beneficial insects (all natural, genetically engineered by mother nature) are small pest-fighting farm animals, not pesticides. These biological control organisms are chosen from successful farms, propagated in large numbers for release by farmers who want to transition to more sustainable pest control.
Fifty to 75 percent pest control cost savings have been reported within the first two years by growers transitioning from conventional total chemical farming to an Integrated Predator/Parasite Management program that maximizes beneficial organisms.
BIOLOGICAL CONTROL IN VEGETABLE CROPS
Rincon-Vitova's five-point program emphasizes (1) colonizing beneficial insects, (2) limited plantings of cover crops that trap pests and provide refuge for their parasites and predators, (3) monitoring of insect populations to assess the progress of both pests and beneficials, (4) selective spraying techniques and (5) the utilization of cultural practices that minimize pests. Rincon-Vitova calls its program Integrated Predator/Parasite Management or IPPM (as opposed to Integrated Pest Management or IPM which often overlooks the role of beneficials in pest management). Here is a review of our five-point IPPM program.
Rincon-Vitova's Five-Point IPPM Program
1 - Beneficial Organisms
Repeated use of all classes of chemical poisons on many farms in an area results in immunity of insects 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. Insectary-reared beneficials can selectively help restore the natural enemy complex.
Rincon-Vitova's Five-Point IPPM Program, continued
2 - Cover crop 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 nectar and overwintering sites. Sunflower and sorghum borders are particularly good habitats for growing lacewing and other natural enemies on the farm. Researchers have found that two plantings of sunflower borders 30 and 60 days prior to planting processing tomatoes yielded natural enemies that controlled incoming sweetpotato whitefly. Lacewings released in forage sorghum interplantings increased lacewing eggs on cabbage by 1,000%. Corn and alfalfa borders and interplants, unsprayed sorghum, grains, oil seed Brassicas, wild flowers, red-root pigweed (Amaranthus retroflexus) and cover crops can also increase Trichogramma parasitism of moth eggs.
3 – Monitoring
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. D-Vac vacuum insect sampling gathers both pests and their beneficials, large and small.
4 – Spraying
Do not spray if there is no pest problem! Pesticide interference to beneficials should be avoided if it has adverse effects on the balance of pests and their natural enemies. Certain dosages of conventional pesticides and insecticidal soaps and oils are less disruptive to biological controls. Our beneficials are compatible with "soft pesticides" like Bt's (e.g. Dipel, Javelin), sterile male releases and pheromone mating disruption (e.g. Attract 'n Kill and NoMate), making them good additions to the more sustainable, "non-toxic" IPM programs.
5 - 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.
IPPM emphasizes beneficials and seeks to suppress particular pest levels so that rather than 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 IPPM method gets easier each year, as a reservoir of natural enemies becomes established. Sometimes, however, the progress of biological control is too little and too late. When pest populations increase beyond tolerable limits and there is no predictable chance of obtaining a favorable biological balance, sprays of so-called "soft pesticides" are suggested to buy time until harvest by preventing damage to the market product.
BENEFICIALS PROTECT THE FARM
Among the hundreds of beneficial species commonly devouring agricultural 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 Trichogrammatids, such as Trichogramma and Trichogrammatoidea species. Rincon-Vitova's biological control organisms, it's many species and forms of Trichogramma wasps, green lacewing and other predators and parasites, are there to support pest management in vegetable crops. 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.
One approach cited for planning Trichogramma releases is to aim for a ratio of 1 parasite per 10-20 pest eggs. This can boost parasitization into the 90-100% range when fields are monitored and releases are timed with pest egg laying. For light infestations of cabbage loopers in cole crops early in the season Ridgway (1981) suggested releasing 25,000 Trichogramma twice a week. For medium and heavy infestations, 50,000 and 100,000 were suggested. Reports from former Soviet republics indicate that 20,000 Trichogramma per acre, or 1 parasite per 20 pest eggs, produces 90-100% parasitization of cabbage worm eggs.
Fifty to 80 percent parasitism by Trichogramma of the eggs of Heliothis or Helicoverpa (i.e. tobacco budworm, tomato fruitworm, corn earworm) are always followed by drastic reductions in worm populations, especially when releases are combined with green lacewing releases and border or intercrop habitat management. If the rate of Heliothis eggs is 25,000 per acre, such reductions can be accomplished with 25,000-100,000 Trichogramma per acre. For light infestations, 10,000 Trichogramma per acre per week has been suggested; heavy Heliothis infestations should receive a minimum of 30,000 per acre twice per week.
Rincon-Vitova entomologists meet the challenge of successive corn plantings by starting when the first planting is a foot high. One release of 5,000 Trichogramma pretiosum per acre anticipates the first moth flight to start the battle against tassel worm. A release of 5-10,000 hatching lacewing larvae and weekly releases of 10,000 Trichogramma per acre are then timed as close as possible to egg-laying, especially when silks develop, and with heavier distribution in hot spots to stop second generation moths. A second lacewing release 7-10 days after the first will help create overlapping generations of lacewing larvae feeding steadily over subsequent plantings. Quantities per week of Trichogramma can be decreased through subsequent plantings, especially if these early Trichogramma and lacewing releases are nurtured in cover crop strips. They will be present to suppress aphids, mites and armyworms, as well as Spodoptera and Heliothis tassel worms.
Trichogrammatoidea bactrae, an Australian import that attacks pink bollworm also destroys other "micro" lepidopteran eggs, including diamondback moth, tomato pinworm, and peach twig borer. Rincon's entomologists are excited about this new natural enemy, 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.
Rincon-Vitova's "Farming with Green Lacewings" reviews research which generally suggests a predator:pest ratio of at least 1:50 (in celery and dill) to 1:25 (parsley and eggplant) to 1:15 in the spring-summer period in fast-growing crops to as high as 1:1 to reduce waxy aphids in fall cabbages. In the Ukraine, 2-3 releases of C. carnea (50-60,000 per year) at 10-15 day intervals were 85-96% effective against Colorado potato beetle on potato. In Finland, 40 lacewing eggs/square meter controlled green peach aphid for three months on greenhouse asparagus. Remarkable efficacy for seeking and consuming sweet potato whitefly eggs and larvae were observed from 100 Chrysoperla rufilabris larvae released two times in the centers of 12 hibiscus plant in Texas greenhouses. Rincon-Vitova's custom- mixed spring and fall species ratios of lacewing are the most cost-effective predators for use in IPPM demonstrations in vegetables and melons where SPWF is a major pest.
Limited quantities of the tiny lady beetle Delphastus pusillus, a voracious predator of sweetpotato and poinsettia whiteflies, can also be inoculated into field crops. Each of these high-density feeders consumes as many as 10,000 whitefly eggs or 700 4th instar larvae. 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. The minute pirate bug (Orius) is also available for inoculation. It is attracted to thrips, but eats almost any tiny insect or mite. Growing Orius in irrigated areas helps when surrounding hosts of thrips dry up. Orius numbers increase in cover crop strips or border plantings which can be managed to drive this important predator into market crops at critical times.
TRANSITIONS TO BIOCONTROL MADE EASIER
None of the beneficial species sold by Rincon-Vitova Insectaries is intended to be used as a pesticide for quick insect kill. Periodic early season releases help maximize the effectiveness of existing natural enemies, guaranteeing overlapping generations of these key parasites and predators to be present when needed. For example, general predators, such as lacewing and ladybugs, help in early season aphid control, then defeat spider mites. Trichogramma releases keep many worm (caterpillar) eggs from hatching, but late-season biological control of worms by predators is one of many examples of the integrated management of predators and parasites that can only happen by 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.
Trichogramma pretiosum, Trichogrammatoidea bactrae, green lacewings, predatory mites for two-spotted spider mite, Western flower thrips and onion thrips, stink bug parasites and other Rincon-Vitova beneficial organisms in an IPPM program should be nurtured into reproducing in the field. Rincon-Vitova provides customers on account with updated bulletins about such practices. For example, the latest Lacewing Bulletin offers tips for ant management and luring and nurturing lacewings and other predators. Bulletins about biological control solutions for cotton pests and for pecan pests offer more about cover cropping and strip cutting.
Rincon-Vitova also 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, have been successful in transition situations due in part to this hardiness and ability to withstand some chemical residues.
PUTTING IT ALL TOGETHER
Each point in our five-point IPPM program contributes to the success of biological control. Insects have their place on the farm in balance, rather than as flare-ups resulting from migrations into "enemy-free space". Cover crops and cultural management provide natural reservoirs and havens for beneficials. Appropriate species and management of cover crops and borders not only multiplies beneficials relative to pests, but maintains or increases soil fertility and provides vegetative barriers to erosion and waste of soil, water and fertilizer. Monitoring must be thorough and holistic, anticipating the future progress in the ratios of pests and beneficials. Spraying with least toxic materials over minimal areas is a late-season last resort weighed carefully against the crop value to be gained.
Customers on accounts of Rincon-Vitova Insectaries are informed about new beneficial species, some of which are so scarce that only very small quantities can initially be provided for inoculation. Where demand is sufficient, we can on special request obtain rarer natural enemies not normally available commercially. Computerized literature data-base searches and species identification services are available. The combined experience of our in-house and associate entomologists over more than 40 years of pioneering in both classical and augmentative commercial biological control make this possible. Our specialists stand ready to contract for services in all crops worldwide.
A variety of technical bulletins and papers are available covering the use of our beneficials in orchards, cotton, greenhouses and nurseries, interiors, and gardens. 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.