IInnsseecctt MMaannaaggeemmeenntt oonn OOrrggaanniicc FFaarrmmss by H. M. Linker, D. B. Orr, and M. E. Barbercheck

nsect management presents a challenge to satisfactory control of chronic pest species. IIorganic farmers. Insects are highly mobile Certified organic farmers can use a wide and well adapted to farm production range of practices to create an integrated pest systems and pest control tactics. On organic management approach that complies with the farms, where the focus is on managing insects standards of the USDA’s National Organic rather than eliminating them, success depends Program (NOP): www.ams.usda. gov/nop/, on learning about three kinds of information: (202) 720-3252. The standard states that a farmer must use management practices to • Biological information.What the insect prevent crop pests, weeds, and diseases, needs to survive can be used to determine if pest insects can be deprived of some vital resource. • Ecological information. How the insect interacts with the environment and other species can be used to shape a pest- resistant environment. • Behavioral information about both pest and beneficial insects. How the insect goes about collecting the necessities of life can be manipulated to protect crops. This knowledge can be used to craft a management plan that incorporates many different elements to suppress pest insects. No Figure 1. Striped cucumber beetle (Acalymma vit- single tactic, employed alone, is likely to give tatum) (Photo courtesy of USDA.)

Contents Cultural Practices—Page 2 Biological Control Using Insect Natural Enemies—Page 17 Pheromones and Other Attractants—Page 8 Insecticides—Page 26 Biological Control Using Insect Pathogens—Page 10 Recommended Reading—Page 33

species and encourage their natural including but not limited to these: crop enemies, also referred to in this chapter as rotation and soil and crop nutrient beneficials. management practices; sanitation measures to • Pheromones and other attractants. remove disease vectors, weed seeds, and Organic farmers can use chemical habitat for pest organisms; and cultural attractants to trap pest insects, disrupt practices that enhance crop health, including their reproduction cycle, and monitor selection of plant species and varieties that are their population levels. suitable to site-specific conditions and Biological control using insect resistant to prevalent pests, weeds, and pathogens. Organisms that cause disease diseases. in insects can be exploited to help control pest populations by managing the According to the organic standard, insect pest environment to favor insect disease or by problems may be controlled through cultural, applying allowable purchased products. mechanical or physical methods; augment- The use of insect pathogens to manage ation or introduction of predators or parasites pests is called microbial control. of the pest species; development of habitat for • Biological control using insect natural natural enemies of pests; and nonsynthetic enemies. Farmers can manage their fields controls, such as lures, traps, and repellents. to provide habitats for species that eat and When these practices are insufficient to live on pest insects. This can be prevent or control crop pests, a biological, accomplished through conserving and botanical, or chemical material or substance augmenting beneficial populations. included on the National List of nonsynthetic • Insecticides. Allowable organic and and synthetic substances allowed for use in inorganic chemicals, insecticidal oils and organic crop production may be applied to soaps, microbial insecticides, particle prevent, suppress, or control pests. However, films, and botanicals, when used in the conditions for using the material must be combination with the above pest documented in the organic system plan. management strategies, can help to suppress pest insect populations. Pest management plans are site-specific. Farmers should develop their own strategies based on their knowledge, available time, and All of these practices used together comprise capital—the resources they can devote to pest an integrated pest management (IPM) management. This chapter provides basic approach. information on pest insects and the management tactics that organic farmers can CULTURAL PRACTICES: THE PLACE TO use to keep pest insect populations at levels START that do not pose an economic threat to crops. It is not a how-to guide that can be followed Pest insect problems are influenced by three step by step. We will focus on the following components of a farming system. Farmers can topics: manipulate all of these components to suppress pest species. • Cultural practices. The first key step toward managing pest insects is using • The crop species and cultivar present a set of cultural practices that suppress pest resources, growth habits, and structure.

Organic Production Series— Insect Management 2

• Production practices, such as rotation, insects. This can involve one or all of the timeliness of planting and harvesting, following strategies: spacing of plants, fertility and water management, tillage, mulching, sanitation, • Reducing initial pest levels by making the and companion planting. crop environment unattractive, • Agroecosystem structure includes field unfavorable for pest reproduction and borders, natural vegetation, and other growth, or both. crop production areas that resupply fields • Producing favorable conditions for with pest insects and beneficial species natural enemies. when crops are replanted. • Increasing the plants’ ability to withstand pest damage. Insects require a basic set of resources to live When used together, the cultural practices and reproduce. Production practices that described on the following pages provide deprive a pest species of at least one needed useful tools for reducing or preventing pest element of life may maintain pest populations problems. below economically damaging levels for extended periods. It is unlikely, however, that cultural practices will provide permanent Monitoring control because the most troublesome insect Monitoring insects is fundamental to good species are those that are well-adapted to the management. Determining when a pest insect production systems used on a farm. first colonizes a crop and measuring its abun- Populations of these pest insects will tend to dance on a regular schedule provides the in- increase under a particular production formation needed to make control decisions. system, while populations of less well- adapted species will decrease. Monitoring does not have to be a rigorous procedure, but it needs to be done on a regular Pest insects must be very adaptive to succeed basis using the right procedure. because their physical environment changes as production systems change. Insects must In some cases (as for mites and aphids) simply deal with many environmental changes, checking crops by direct observation is all that is including different tillage practices, fertility needed. For other pests, it is easier and quicker to regimes, and planting dates. Each individual use a device, such as a sweep net, to sample practice can change pest insect population crops. Many devices—from plastic lunch trays to dynamics. In organic systems, farmers use ground cloths—are used to sample pests. Some many different cultural practices and cultivate pests, like thrips, require a different procedure. a wide array of crops. The interactive effect of this array of interacting elements on pests is Local Extension offices have information on how difficult to predict and usually can be and when to monitor many crops for pests. This determined only through research and procedure is essentially the same for organic or experience. conventional crops.

Farmers can use cultural control measures to modify the crop environment enough to increase environmental resistance to pest

Organic Production Series— Insect Management 3

Crop Cultivar mobile foliar pests—such as the Colorado potato beetle (CPB), subterranean pests, or Plant breeders traditionally have placed more pests with one generation a year—may be focus on creating disease-resistant varieties substantially suppressed with proper rotation. than on creating insect-resistant varieties. The distances required, however, may exceed Where they are available, however, insect- the space available on small-scale operations. resistant varieties can be an effective defense. For example, to reduce insecticide It is important to find out about the applications for CPB by 50 percent, potatoes mechanism of insect resistance in a crop have to be moved 1/4- to 1/2-mile away from variety because genetically modified crops previous potato crops (Weisz et al. 1994). To (GMOs, transgenic crops) are not allowed in be most effective, rotations between organic production systems. Even when susceptible crops should be three to seven insect-resistant cultivars are not available, years. some varieties may be less attractive to pest species or tolerate more damage than others. Planting Date and Method Plant size, shape, coloration, leaf hairs, and natural chemicals—both attractants and The stage of crop development can have a repellents—all affect the outcome of insect profound effect on a crop’s attractiveness to crop colonization. Note that changing pest insects. For some pests and crops, stage cultivars to reduce pests can also reduce of development dictates whether or not a pest beneficial insects either directly is a problem. If very few crops are available (characteristics that affect pest abundance when insects emerge in the spring, pest may also influence beneficial insects) or insects may concentrate on a few early indirectly (through providing less prey). planted fields. Conversely, if many crop and noncrop host plants are available in early Although resistant varieties and natural spring, then pests may disperse widely and controls generally work together to suppress not concentrate in any one crop. Thrips, for pests, some exceptions have been example, often infest early planted crops in documented. If difficult, persistent pest high numbers. But they cause fewer problems problems occur, selection of a resistant or on later planted crops. For some pest insects, more tolerant cultivar is an option that should planting a crop early so that it reaches a less be tested. Most land-grant universities have susceptible physiological stage can be a official variety tests that may include practical solution to a pest problem. For observations or screening on insect resistance. example, corn earworm causes fewer Often, however, farmers must depend upon problems in early planted sweet corn. observation, experience, and exchanging Additionally, aphid-transmitted plant viruses information with other farmers. may be minimized in early planted crops.

Crop Rotation Vigorous crop growth is also important. Seeds should be sown when temperatures will allow Crop rotation or sequence is designed to them to emerge and grow quickly. Using present a nonhost crop to pest insects. seedlings or transplants instead of seeds can Realistically, rotations are likely to have little also speed crop development. Plants effect on highly mobile foliar insects. Less struggling to survive or plants under stress

Organic Production Series— Insect Management 4 will be more attractive to pest insects and Organic production does not allow synthetic more affected by damage. fertilizers or sewage sludge. Check with your certifier if you are in doubt about your fertility Most of the time, planting date and method management materials. are dictated by markets, weather, labor availability, and other factors. But if a pest Although crop plants must grow vigorously insect presents an especially difficult problem, to withstand pest damage, overly lush plants manipulating the planting date and method often attract more pest insects and experience may be one option to explore. more damage than other plants. Overfertilized plants may give visual clues to Harvest Date insects and become targets of attack. Survival The shorter the time a crop is in the field, the less of immature insects may also be better on time pest insects have to damage it. Combining overfertilized plants. Nutrient stress from early planting with early maturing varieties may insufficient plant nutrients can also cause allow a crop to mature before pest insects reach plants to be more attractive to insect pests or damaging levels. more susceptible to damage by insect pests. Consequently, the careful planning and This can also be effective for minimizing insect- execution of soil fertility programs (including transmitted plant diseases. For example, curcubit pH) is an important component of pest insect crops may have fewer virus problems with early management. harvest. Other factors, however, such as markets and weather, may dictate longer seasons. This Increasing Soil Organic Matter must be weighed against insect pest losses. Studies have shown that as organic matter in the soil increases, microscopic life increases, which Crop Population Density —Row Spacing can lead to an increase in generalist insect & Seeding Rate predators.

Decisions about crop population densities are Additions of organic matter must be handled dictated more by the growing characeristics of carefully because some soil-dwelling pests, such the crop, weed management, and harvest as the seed corn maggot, can present significant requirements than by pest insect problems. Only throughly composted materials, management. In general, if increasing the well incorporated, should be used to minimize population density of a crop increases soil pest insect problems. beneficial insects, it can lead to a decrease in pest insects. In some crops, close row spacing Water Management increases control by beneficial insects. More ground shading will usually increase ground- Irrigation has both direct and indirect effects dwelling predators, such as ground beetles. on pest insects. Insect populations can Some species of ground beetles also consume decrease if overhead sprinklers knock insects weed seeds on the soil surface. off plants or raise microenvironment humidity enough to encourage insect disease Fertility Management—Nutrition, Vigor, caused by bacteria or fungi. Because irrigation and Soil pH methods vary considerably (whether drip, overhead sprinkler, or flood irrigation), the Proper nutrient management is an important impact of irrigation on insects also varies. Pest component of IPM in organic systems. insect populations can increase if irrigated

Organic Production Series— Insect Management 5 plants are lusher and more attractive than reliably predicted. Species shifts will occur surrounding plants. Likewise, plants stressed and should be carefully monitored. Tillage is by drought can be more attractive to insect not likely to have a significant effect on most pests or less tolerant to their feeding. The common foliar-feeding insect pests. need for irrigation is dictated by crop growth and weather rather than the need for insect Mulches control. But when there is some flexibility in irrigation scheduling, a farmer should think Mulching systems fall into various categories, about irrigation as a tool for suppressing pest including plastic (woven or nonwoven) and insects. Several naturally occurring insect natural materials. Although allowable, the use pathogens, especially insect-pathogenic fungi, of plastic mulch is frequently discouraged by provide effective pest suppression when high organic certification agencies because it relies humidity microenvironments are created. on a nonrenewable resource. Biodegradeable

plastic mulches are being developed and may Tillage affect pests in a similar way to that of conventional, nonbiodegradeable muclhes. Tillage practices affect both subterranean and Organic farmers often use a straw mulch foliar insect pests. Infrequent disturbance of because it is readily available and provides soils in natural systems preserves food webs good weed suppression. Planting into a living and diversity of organisms and habitats. The or killed mulch is growing in popularity as regular disturbance of agricultural soils more information on this practice is provided disrupts ecological linkages and allows and as specialized equipment becomes adapted pest species to increase without the available. (See the discussion of cover crops in dampening effects of natural controls. this chapter, under “Conserving Natural Nevertheless, tillage can also destroy insects Enemies,” page 15) New systems, such as overwintering in the soil as eggs, pupae, or hydromulch (which consists of wood fibers adults, and reduce pest problems. sprayed on with an adhesive to keep them together) may one day supplant plastic and

Organic producers usually rely on tillage to straw if they are developed with organically control weeds and to prepare the soil for allowable components. For now, plastic and planting. Research is being conducted on straw mulches remain high in popularity. methods and equipment that may allow for All mulches suppress insects in comparison to the reduction of tillage in organic systems. bare soil. Different colors of plastic have been Some practices to reduce tillage in organic tested; and clear, white, yellow, or aluminum systems include zone tillage, ridge tillage, and (reflective) colors may provide some including a perennial or sod-producing crop additional suppression of aphids and in the rotation. Reduction of tillage alters pest whiteflies. Blue and yellow may bring in more insect dynamics considerably. Thrips cause pests. Plastic can be painted the desired color. fewer problems in reduced-till systems. Before painting mulch, farmers should check Ground-dwelling predators, such as ground with their certifiers to see if the practice is beetles that prey on pest insects, can increase. allowable. However, cutworm and slug problems can also increase where tillage is reduced. The Straw mulches can affect insect pests. Crops degree of pest population shifts between a that are traditionally mulched with plastic tilled and reduced-tillage system cannot be may benefit from straw mulches. For example,

Organic Production Series— Insect Management 6 Companion Planting suppression of the Colorado potato beetle has been demonstrated with straw mulch in The companion planting approach is based on potatoes. Not enough information is available the theory that various plants grown in close to make definite recommendations about the proximity to the crop plant will repel or kill advantages of one mulch over another. pest insects. Studies to date have not shown Testing in a restricted area is recommended this approach to be effective. Note that when using mulches for the first time or companion planting is not the same as changing mulching materials. Mulching alone intercropping, which may be a valuable tool will probably not prevent pest problems. in attracting beneficial insects. Nevertheless, if used in combination with other tactics, mulching may help reduce populations of difficult insect pests. Trap Crops

Sanitation Trap crops attract pest species away from the cash crop to be protected and into a specific Good farm sanitation can help to prevent area where they can be destroyed. Depending introductions of pest insects from outside on the target pest and the cash crop, trap sources, slow their movement within the crops can be planted with or around the farm, and eliminate them when they are perimeter of the cash crop field. This discarded with crop materials that may approach is an appealing idea, and it has harbor them. proven useful in some situations. Implement- ation of trap cropping takes careful manage- If transplants are purchased off-farm, buy ment. Knowledge of the biology and ecology from a reputable dealer and check very of the target pest species is critical when carefully before bringing transplants to the considering trap cropping. Species that are farm. A simple screening process can save weak fliers or pests that are blown into a crop time and money later. Quarantine any (such as aphids) or are dispersed in the wind purchased transplants for at least a week, and (such as spider mites) are not good examine them carefully for pests daily. candidates. Good target pests show a strong preference for a particular type, variety, or Some pests (such as spider mites and physiological stage of the crop. whiteflies) are not very mobile but can spread when people and equipment move from an The size and configuration of the trap-crop infested area to uninfested areas. After area usually is not based on the size of the working in an infested area, clean equipment cash-crop area but on the number of pests and clothes before going to another area of the expected. A small trap-crop area that is farm. quickly destroyed will not give satisfactory results. If enough land is available, it is better Culled plants and produce are often piled to have a trap-crop area that is too large rather near the field or processing area for later than one that is too small. Some trap crops are disposal. This can provide a suitable feeding planted within the field of the cash crop. and breeding site for insect pests. These piles Another approach, called perimeter trap should be composted, buried, or otherwise cropping, involves planting at least two rows destroyed as soon as possible. of the trap crop around the entire perimeter of

Organic Production Series— Insect Management 7 insects can make a sound as loud as a the cash crop. An approach to trap cropping chainsaw; others have striking colors. Many that improves efficacy is to combine it with insects find each other over long distances by other tactics. For example, with a push-pull emitting chemical signals or pheromones to approach, a trap crop is used to pull the pest attract individuals of the same species into an species away while the protected cash crop is area so they can find each other to mate. Once intercropped with a plant that repels pests. the individuals get close together, visual This approach has been used successfully to cues—such as color, shape, and behavior— protect maize in Kenya. become more important. Entomologists have Trap cropping was originally designed to be determined the chemical structure of used in conjunction with a highly effective pheromones for many pest species and insecticide to kill pest species in the trap crop. duplicated them synthetically. In organic systems, however, there are few Insects also use other chemical messages. allowable insecticides, so it is important to Chemical cues to the location of food can know if there are allowable insecticides that draw insects into a particular area where, are effective and economical to use against the once they get close enough, visual and tactile expected target pest, or that the trap crop is cues lead them to food sources. destroyed before the target insect moves onto the cash crop. Correct timing of crop Pheromones and other chemical attractants destruction is important: Destroying the trap can be used in several different ways: to crop either too early or too late can have monitor pests, disrupt mating, capture a large negative consequences. In addition, any number of adults (called mass trapping), beneficial insects colonizing the trap crop will distribute an insect pathogen or or lure pests also be destroyed. to consume poisoned bait. Any trap baited with an attractant must be used carefully. Knowledge and record-keeping can help Some research has demonstrated that a trap improve the performance of trap cropping. can bring more pests into an agroecosystem For example, one approach may be to plant a than it kills. small area of the cash crop very early so it can reach an attractive physiological stage before the primary planting. Variations in growing conditions (for example, if conditions are too dry or too cold) can change the timing of physiological stages so that it is possible to end up with both crops in the same physiological stage. Keeping good records of weather conditions and performance of the trap crop and the cash crop will help in developing pest management systems.

Figure 2. Pheromone traps often have a characteris- PHEROMONES AND OTHER tic triangular shape. (Photo courtesy of ATTRACTANTS www.insectimages.org.)

Chemicals that trick pest insects to expect Insects are very small creatures in a very large food or mates can be very effective at world. They have evolved many different attracting insects from long distances. The ways of finding each other to mate. Some

Organic Production Series— Insect Management 8 result. Because there are fewer immature primary use of these chemicals has been to insects, crop damage is minimized or monitor pest activity. New traps and baits, eliminated. In some cases this approach has however, are showing the potential to reduce worked well. pest abundance directly.

Like most control measures based upon insect Using Pheromones to Monitor Insect behavior, however, successful disruption of Populations insect mating requires an understanding of some basic concepts. For example, Monitoring insect pests is one of the most pheromones emit a plume of chemical carried effectives uses for pheromones. They can be on the prevailing wind. During the course of used to detect the first arrival of a pest insect the mating season, wind shifts and eddies will species or an increase or decrease in distribute the pheromone over a wide area. populations. Attractants are used in several Males detect this plume and follow it into the different types of traps (including sticky, wire, area where the pheromone is located. This mesh, pan, and water traps) that all work on plume can be carried a long distance and may the same basic principle: Attract insects to the actually attract males that otherwise would trap where they can be captured and counted. not be in the immediate area. If the number of Because each trapping location is unique and males in the vicinity is increased, then the net the patchwork of crops and noncropland effect may be to increase the number of shifts yearly, interpreting the importance of mating males. the arrival time or the number of insects Concentrated applications of pheromone are trapped comes with experience. generally used for this method. The proba- bility of success increases if more pheromone Often the peak number of insects counted is is used and the release rate (frequency) is less important than the length of time they are stepped up. This approach can give results present. Most pheromone traps attract males, equal to or better than conventional insect- which are indirect indicators of potential pest icides. Instructions from the supplier should problems. Also, when females are in the area, be followed carefully. they can be more successful than traps at attracting the males. For the right species, Mating disruption is not foolproof, and it is however, and with experience, pheromone important to understand when it may not be traps can be effective and inexpensive useful. Pheromones are specific to each pest monitoring tools. species and are only effective for insects that

find mates over long distances. Insects that use visual cues to find mates will not be good Using Pheromones to Disrupt Mating candidates for mating disruption.

Mating disruption works by permeating the Also, the use of pheromones is usually an crop environment with a chemical message expensive option. Another concern is that that prevents pest insect adults from locating previously mated females can fly into the each other to mate. The logic of using protected area and cause economic damage. pheromones to disrupt mating is simple: If For high value crops, the offspring of a few enough males can be confused so they cannot mated females can cause a large amount of find mates, then almost all females are crop damage. So it is wise to consider the area unmated and fewer immature insects will

Organic Production Series— Insect Management 9 based product that you want to use is allowed surrounding the crop of interest to determine by your certifier. if it is hospitable to the pest species.

Very high populations of pest insects may not Insect-Parastic Nematodes respond to mating disruption with pheromones if they are able to respond to Traditionally, soil-inhabiting insect pests have visual cues from their close proximity to each been managed by the application of pesticides other. If no other control choice is available, to the soil. Interest in biological control to then it may be necessary to try mating manage crop pests has increased because of disruption. For a complete discussion of concerns about the economic, environmental, pheromones, see this Web site: and health costs of chemical crop protection http://ipmworld.umn.edu/chapters/flint.htm and because of the need to develop production systems that are environmentally Using Pheromones for Mass Trapping and economically sustainable. Insect-parasitic nematodes show promise as Pheromones can be so powerful that many or biological control agents for soil pests. most of the adults insects in an area can be Nematodes are microscopic, whitish to trapped and killed. It is easy to conclude that transparent, unsegmented round worms. so many are caught that the number Nematodes in the families Steinernematidae remaining cannot cause substantial crop loss. and Heterorhabditdae have been studied Insects, however, can mate repeatedly. So the extensively as biological control agents for remaining males will usually be sufficient to soil-dwelling insects. These nematodes occur keep pest populations at economically naturally in soil and possess a durable and damaging levels. Studies have demonstrated motile infective stage that can actively seek that more than 95 percent of the males must out and infect a broad range of insects. They be destroyed before populations decline. do not infect birds or mammals. Because of Achieving this level of destruction is not these attributes, as well as their ease of mass practical for most farmers. production and exemption from EPA registration, a number of commercial BIOLOGICAL CONTROL USING INSECT enterprises produce insect-parasitic PATHOGENS nematodes as biological “insecticides.”

Insects have many types of natural enemies. As with other organisms, insects can become infected with disease-causing organisms called pathogens. Soil serves as a natural home and reservoir for many kinds of insect pathogens, including viruses, bacteria, protozoa, fungi, and nematodes. Pest control products based on insect pathogens are available commercially, and some products are allowed in organic production. As with all pest control products, it is critical to Figure 3. Tiny worm-like Heterorhabditis nematodes determine if the specific insect-pathogen- have killed this wax moth caterpillar. (Photo cour- tesy of www.insectimages.org.)

Organic Production Series— Insect Management 10

Life Cycle. The infective third-stage conditions — adequate moisture, tempera- (sometimes referred to as the dauer or IJ stage) tures within the tolerance levels for the is the only life stage wherein the nematode nematode, and protection from ultraviolet exists outside of the host insect. This is the radiation during application. stage that is available as a commercial Nematodes are very sensitive to destruction product. by bright sunlight and to desiccation if they are applied to plant foliage. This limits their Upon locating a suitable insect host, the use mainly to soil, although there are some infective juvenile enters the insect through instances where they have been successfully natural openings (the anus, spiracles, and applied above-ground to insect tunnels or mouth) and penetrates the insect body cavity. mines in plant tissue. The nematodes develop and reproduce in the infected insect. Two to three generations occur Nematodes are formulated as suspensions in in the insect cadaver. liquid, on sponge, in gels, or as semi-dry granules. The main application approach is as As resources are depleted and crowding suspension in water at a typical rate of 1 occurs, infective juveniles (IJ) are produced. billion per acre, but this rate varies depending The IJ emerge from the cadaver to search for on the crop. They can be applied with new hosts. The reproductive potential of conventional chemical application equipment, insect-parasitic nematodes is very high: but screens in nozzles should be removed Thousands of nematodes can be produced when applying nematodes with a back-pack from a single mated pair. The time from sprayer or spray rig. Nematodes tend to settle infective juvenile to infective juvenile takes in the tank, so agitation must be provided for about two weeks in the laboratory. Under uniform application. Nematodes can also be natural conditions, the recycling time will applied with irrigation. However, some vary depending on environmental conditions irrigation systems, especially low-volume and the susceptibility of the host insect. trickle systems, may not move water fast enough to keep nematodes suspended. When Application. Some nematodes that are in doubt, check periodically by taking a commercially available are Steinernema sample at the emitters to determine if live carpocapsae, S. feltiae, S. riobrave, Heterorhabditis nematodes are being moved through the bacteriophora, and H. megidis. Treatment with system. these nematodes can be expensive, and they are most commonly used for managing soil Conserving Nematodes. Insect-parasitic insect pests in high-value crops, such as turf, nematodes occur worldwide, and they have nurseries, citrus, cranberries, and mushrooms, been found throughout the U.S. in many as well as in home lawns and gardens. As different soil types and habitats, both natural production technologies improve, however, and managed. We do not yet know what level the cost of using nematodes is falling, and it of natural insect control these nematodes may be economical to use them in lower value exert, or how to predictably increase the levels crops. of natural control to an economic level of control. Native nematodes may play an The efficacy of nematodes in the field can be important role in regulating insect variable. Their successful use probably populations in some farm systems, but the depends on favorable environmental level of disturbance in agricultural systems

Organic Production Series— Insect Management 11 may require the use of non-native nematodes applications are related to a poor match that are tolerant to the farming practices being between the nematode species and target used. insect. Species of nematodes vary in their host range and in their host-finding behavior. Some studies suggest that insect-parastic Some nematodes—Heterorhabditis nematodes are more abundant in less bacteriophora, for example—are very active in disturbed systems, such as orchards or the soil and search a relatively large area for a pastures, and in minimum- or no-till plots host insect, whereas others—Steinernema than in conventionally tilled plots. Different carpocapsae, for example—are relatively nematode species are differentially tolerant to sedentary and tend to wait for a host insect to soil disturbance. Survival of insect-parasitic pass by in close proximity. A nematode that is nematodes is higher in mulched soil than in an active searcher will be more effective than bare soil, probably because of differences in a sedentary nematode at finding a sedentary soil physical structure, temperature, and insect host, such as a white grub. The rela- moisture. tively sedentary nematodes are effective at infecting active insect hosts, such as cutworms Research to determine the effects of pesticides or mole crickets. Some appropriate nematode on insect-parasitic nematodes has shown that host targets are known: some pesticides and fertilizers are less harmful to nematodes than others. • S. scapterisci against mole crickets; Compatibility with pest and fertility • S. carpocapsae against cutworms and other management materials is usually provided on mobile caterpillar pests; the product labels or packaging information • S. riobrave against cutworms and other that accompanies purchased nematodes. noctuid larvae and pupae and citrus weevils; Efficacy of Treatment with Nematodes. • S. feltiae against sawfly larvae and fungus To date, the level of control achieved by gnat maggots; and applying nematodes has varied, with some • H. bacteriophora against white grubs and failures and some successes. The successes other sedentary soil-dwelling beetle have occurred mostly in simplified, controlled larvae. systems such as nursery containers. The efficacy of nematodes is affected by Product viability. As with any purchased environmental conditions: They need natural enemy, product quality can affect adequate but not excessive moisture, efficacy. The viability of the product can vary temperatures within the tolerance levels for by batch and can be affected by shipping, the particular nematode, and protection from storage, and application conditions. UV radiation during application (apply early Nematodes are living organisms that are in the morning or in the evening). Some subject to destruction by excessive cold or research has indicated that the type of plant heat and lack of moisture or oxygen. A small an insect eats can affect its susceptibility to sample of the mixed product should be infection by insect-parasitic nematodes and checked with a magnifying lens to observe other types of pathogens. viable, moving nematodes.

Nematode species and target insect. Most For additional information about using failures in the effectiveness of field nematodes as pest management tools, see

Organic Production Series— Insect Management 12 www2.oardc.ohio-state.edu/nematodes — increase the speed of kill or prevent Insect Parasitic Nematodes: Tools for Pest competition from other microbes. Management. This SARE-funded Web site has information on the biology and ecology of Usually after the insect has died, the fungus insect-parasitic nematodes, instructions on grows out through the outer covering application, a publications database, an "Ask (exoskeleton) of the insect, usually at thinner the Expert" advice service, a list of retail areas like joints or creases, and begins to suppliers, and links to other sites with produce spores. The spores of commercially information about insect-parasitic nematodes. developed fungi are spread passively by wind, rain, or contact with other hosts or Insect-Parasitic Fungi animals in the environment. Insects killed by fungi often have a “fuzzy” appearance caused Fungi are a diverse group of organisms with by the growth of the fungus out of the close ties to agriculture. Some fungi are used exoskeleton. Most commercial strains of fungi successfully to protect crops from a variety of produce spores that are either white or green, insect pests. Most fungi can cause natural although the color of the fungi can change outbreaks when environmental conditions are over time as the fungus grows and ages. favorable. Several species have been developed as commercial products because of Spores that do not encounter a host either die their ability to be mass-produced. Specific or persist in sheltered areas of crop plants or fungal strains in commercial products target in the soil. Although some species of fungi thrips, whiteflies, aphids, caterpillars, weevils, produce spores that can persist for years in grasshoppers, ants, Colorado potato beetles, the soil, most spores are viable only for a and mealybugs. Currently (2008), allowable growing season or at most a year. products containing the fungus Beauveria bassiana that are commercially available Advantages. Fungi make good insect include Mycotrol O (Emerald BioAgriculture), control agents for a variety of reasons. They Naturalis H&G, and Naturalis L (Troy generally do not affect people or other BioSciences Inc.). Before applying any pest mammals, making them extremely safe to use. control product, make sure that it is currently It is relatively easy to mass-produce spores of allowable by the NOP and your certifier. some insect-parasitic fungi, so they are Life-cycle. Fungi that infect insects are found comparably priced with other biological in the environment as spores. Insects can control agents, such as bacteria. Most become infected when they come into contact commercial fungal products are formulated as with spores on the surface of plants, in the spores, which are easily adapted to existing soil, in the air as windborne particles, or on application technology, such as spray rigs. the bodies of already dead insects. Spores The relatively broad host range of many fungi attach to the surface of the insect and infect by means one can often achieve control of penetrating through the insect cuticle, often at multiple pests with the same product. Finally, joints or creases where the insect’s protective successful infections can spread to other hosts covering is thinner. Once inside, the fungus and lead to high rates of persistence within a grows throughout the insect’s body. Many growing season, even if between-season fungi also produce toxins in the host that persistence tends to be low for most types of fungi.

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timing of fungal applications will not Challenges. There are some challenges to the impact them as strongly. Finally, scouting effective use of insect-parasitic fungi to can help discover natural outbreaks of control pests. High concentrations of spores fungi (for example, aphid fungi) in time to are often needed to get adequate control of influence control decisions. pests in a crop, which can cut down on the • Time applications of fungi to coincide cost effectiveness of fungal products. The kill with a target pest’s life stages so that pests time is relatively long (more or less a week for are more likely to come in contact with the most fungi), although strains used for spores. In general, B. bassiana products are commercial products are chosen to kill as fast more effective against earlier than later as possible. Their broad host range can stages of insects. For example, applying a sometimes be a problem, especially if fungal product for grasshoppers will be beneficial insects (for example, predators, most effective when there are active parasitoids, and pollinators) are present in a nymphs present that have not grown into crop. Nontarget mortality in these winged adults. populations of beneficial insects can • Do not apply fungal products during negatively impact the success of the overall droughts or dry spells because these biological control program. environmental conditions will decrease their effectiveness. Environmental factors can also play an • Be aware of fungicide applications in the important role in the success of fungi. Moist area. Even if fungicides are not directly conditions or high relative humidity in the applied to the crop, drift from nearby crop canopy are often necessary for control to fields could impact the success of a fungal be effective. Prolonged exposure to sunlight biological control agent. can also inactivate spores, reducing • Apply fungal inoculum carefully to get persistence in the crop. Owing to these effective coverage. Cover all plants environmental limitations, natural outbreaks thoroughly. Also try to reduce spillover of fungi tend to be sporadic and very patchy into refuge areas where natural enemies in the environment, which can limit their may be present. effectiveness in controlling pests. • Do not apply fungal products during the heat of the day because this will diminish Application. As with all biological control the potency of the spores. There have been agents, fungi work best as one component of a some reports of phytotoxicity to young multi-tactic IPM program. Farmers can use vegetable transplants with products several tactics to increase fungi effectiveness, formulated as an emulsifiable suspension. especially of commercial products: Also, do not apply on rainy days, when • Scout consistently and often. Apply only spores will be washed from plant surfaces when the target pest is present, not as a and may not come into contact with the preventive application as residues are not target pest. long-lasting. The best time to apply fungi • Use cropping practices that encourage a is before pest populations reach their diverse understory and soil surface, such peak, so early application can increase as cover cropping or conservation tillage. their effectiveness. Also, scouting can help These practices will help maintain fungi in determine the population levels of the field and could increase persistence beneficial insects and pollinators so the within and between seasons.

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Insect-Parasitic Viruses body of the host in fatal infections. The body tissues of virus-killed insects are almost completely converted into virus particles. Insect viruses are obligate disease-causing Infected insects often look normal until just organisms that can only reproduce within a prior to death, when they tend to darken in host insect. They can provide safe, effective, color and behave sluggishly. They often and sustainable control of a variety of insect develop more slowly than uninfected pests, although they are most effective as part individuals. of a diverse IPM program. Some viruses are produced as commercial products, most Most virus-infected insects die attached to the notably for fruit pests, but many others are plant on which they feed. Virus-killed insects naturally occurring and can initiate outbreaks break open and spill virus particles into the without additional inputs. environment. These particles can infect new insect hosts. Because their internal tissues are Commercially available insect viruses that are destroyed, dead insects often look “melted”. allowed in organic production can be found at The contents of a dead insect can range from the National Organic Program’s Web site (see milky-white to dark-brown or black. the list of online references on page x). All are highly specific in their host range, usually While natural virus outbreaks tend to be limited to a single type of insect. These localized, virus particles can spread via the currently (2008) include movement of infected insects; the movement • Gemstar LC (Certis USA), a nuclear of predators, such as other insects or birds polyhedrosis virus of Heliothis and that come into contact with infected insects; or Helicoverpa spp. (corn earworm, tobacco nonbiological factors, such as water runoff, budworm); rain-splash, or air-borne soil particles. Many • Spod-X LC (Certis USA), a nuclear virus-infected insects also climb to higher polyhedrosis virus of Spodoptera spp. (beet positions on their host plant before they die, armyworm); which maximizes the spread of virus particles • CYD-X (Certis USA) and Virosoft CP4 after the insect dies and disintegrates. (BioTEPP, Inc.), granulosis virus of Cydia pomonella, the codling moth; and The number of virus infection cycles within a • CLV LC (Certis USA), a nuclear growing season depends heavily on the polyhedrosis virus of Anagrapha falcipera, insect’s life cycle. Insect pests with multiple the celery looper. generations per season or longer life cycles can be more heavily impacted by virus outbreaks because a greater opportunity Life Cycle. Insect virus particles are usually exists for multiple virus infection cycles found on the surface of plants or in the soil. within a growing season. Insects become infected when they consume plant material with viral particles on the Advantages. Using viruses to control insect surface, although some pests of low-growing pests has many advantages. Insect viruses are plants can be infected by contact with the soil. unable to infect mammals, including humans, which makes them very safe to handle. Most Virus infection begins in the insect’s digestive insect viruses are relatively specific, so the system but spreads throughout the whole risk of nontarget effects on beneficial insects is

Organic Production Series— Insect Management 15 other disease outbreaks developing in very low. Many viruses occur naturally and your crop, which, depending on their may already be present in the environment. extent, could influence other control Even in cases where they are applied, decisions. successful infections can perpetuate the • Apply the virus to maximize the longevity disease outbreak making repeat applications and effectiveness of its particles: within a season unnecessary. 1. Thoroughly coat plants to maximize coverage. Young plants can even be Challenges. A disadvantage of using viruses dipped in a solution of virus particles to control insects is their relatively slow kill to completely cover the leaf area. time. Most insect viruses take several days to 2. Apply in the morning or evening or kill their host insect, during which the pest is on cloudy days when degradation still causing damage. Insect death is also dose- from sunlight is reduced. dependent, and very high doses are often 3. Avoid applying on rainy days, as rain necessary for adequate control. As insects age, will wash virus particles off the leaf they can become less susceptible to virus surfaces. infection, so viruses are usually only effective 4. Use formulations with ultraviolet against early larval life stages. (UV) light blockers and sticking agents to increase longevity. Check Although viruses can persist in the carefully to make sure these environment for months or years, exposed formulations comply with organic virus particles, such as those on plant standards. surfaces, are quickly inactivated by direct • Use mixed cropping, and reduce soil sunlight or high temperatures, which can disturbance after application. These help limit their persistence within a given season. increase the persistence of virus particles Also, some agricultural practices can reduce in the system and may lead to better persistence between seasons, such as tillage, control within and between growing which buries virus particles in the soil. seasons.

Application. Viruses are usually not “stand- alone” solutions to an insect pest problem, but Insect-Pathogenic Bacteria are most effective in conjunction with other management strategies. Although there are Many insect diseases are caused by bacteria. not many commercial products available for The most commonly used bacterial product organic growers in the United States now, available to organic growers is Bacillus several are being developed and may become thuringiensis (Bt). This bacterium produces an available in the near future. insecticidal protein that provides effective control for many pest insects and has very If there is a viral product available, the grower little effect on nontarget insects and natural can do several things to increase effectiveness: enemies. Because Bt products are applied like • Insect viruses are fairly specific, be sure insecticides, it will be discussed in the section that the target pest is correctly identified. on insecticides in this publication. Not all • Carefully scout fields before application formulations of Bt are allowable in organic and apply a virus when the target pests production, so it is important to check with are young but actively feeding. Scouting your certifier before purchasing or using Bt. can also help you discover natural viral or

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BIOLOGICAL CONTROL USING INSECT plant diversity on the farm and the absence of NATURAL ENEMIES conventional pesticides contribute to the provision of a suitable habitat for beneficial The frequency and severity of insect pest insects. That is the good news. The bad news problems depends on the biological and is this: Even high levels of natural control may physical characteristics of the agroecosystem, not be enough to prevent economic damage which is composed of both managed crop from insects that directly attack fruiting areas and unmanaged areas, such as plants. Simple concepts about biological hedgerows. An important component of the control should be re-examined in the light of biological environment is natural enemies or new information. For example, predator beneficials—the predators and parasitoids species (such as ladybird beetles) are often that dampen pest insect populations. Organic credited with a great deal of biological farmers often assume that withholding control. There is little doubt that they do conventional pesticides will have a beneficial contribute significantly. Research has effect on population levels of species that indicated, however, that in many cases, much weaken and kill pest insects. The absence of of the natural control is actually provided by conventional pesticides will likely encourage tiny parasitoids that work in relative the natural enemies of pest insects. But that obscurity.

encouragement may not be enough to provide substantive control of chronic pests without additional changes in the agroecosystem, which provide habitat for the pests and their natural enemies.

Entomologists have different theories about the complexity of agroecosystems and whether diverse or simple agroecosystems are better at enhancing pest insect biological control (Bugg and Pickett 1998). Generally, however, they agree that simplified environments, such as monocultures that consist of a single crop, foster more pest problems. In contrast, a diversified plant environment buffers pest problems by re- allocating insect populations to larger areas and encouraging natural control. This means that the plants growing both inside and outside of cultivated areas must be considered when designing a system to suppress pests. Figure 4. Parasitoids such as this braconid wasp laying its eggs into a caterpillar are important contributors to insect pest management. (Photo Recent research on organic farms shows that courtesy of USDA.) predation and parasitism of pest insect eggs, without any augmentation by the farmer, Natural systems behave in unpredictable could be as high as 85 percent. It appears that ways, and biological control using predators

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and parasitoids is a complex undertaking. The Refugia. This is a noncrop area where complicated interactions are not easily beneficial insects are provided with micro- understood, and directing them in a particular habitats that contribute to their survival and way is even more difficult. persistence. Beneficial insects have enemies, too. They need a place to hide when they are Natural Enemies: Their Survival Needs not searching for prey. This area should also provide overwintering habitat. As a first step, it is necessary to understand that beneficials need year-round habitat and Diversity. In general, the more plant-rich an certain resources for survival. area is, the more likely natural control will work. But some insect natural enemies are Nectar from Flowers or Extra-floral more effective in grass or legume Nectaries. Adult parasitoids feed on and monocultures than in a grass-and-legume often depend upon nectar to help them mixture, so plant diversity does not mature. Studies have shown that longevity universally encourage natural control. and fecundity (the number of eggs laid per No one can provide a blueprint for building a female) increase when suitable nectar sources workable system of natural insect control on a are available. This can have a profound effect specific farm. Many different ways of on parasitism rates and control of pest species. conserving beneficial insects have been tested: Not many plant species have extra-floral managing soil, water, and crop residue; nectaries. Cotton and bachelor buttons are varying cropping patterns and noncrop areas; examples of species that do. Flowering plants and growing plants that attract beneficial have a limited time during which nectar is species. All of these approaches may have available, which can make it difficult or benefits and drawbacks, and making changes impossible for a beneficial insect to use the can be a challenging endeavor because other nectar. So careful planning is needed to activities within the agroecosystem can provide this resource. Pest species, especially conflict with efforts to conserve beneficial insects. For example, cover crops are grown moths and butterflies, will also make use of for many reasons — to add organic matter to nectar sources, which will extend their life, soil, provide supplemental nutrients, and improve their fecundity, and perhaps make prevent soil erosion. The timing of planting, pest problems worse. species selection, and many other decisions Pollen. Adult beneficial insects often use that would be best for these purposes may not pollen as a food source. For example, adult be best for providing beneficial insect habitat. hoverflies use pollen and may need it to Some compromises may have to be made. mature eggs and produce their young, which When considering strategies to enhance are aphid predators. Some predatory insects biological control, it may be helpful to look at are able to complete their life cycle entirely on them in two categories: supplementary food. • Conservation. These techniques conserve Alternate (Nonhost) Prey. Providing a naturally occurring beneficial species. constant source of food will slow emigration • Augmentation. These techniques augment of beneficial insects and keep them at high or supplement the actions of naturally population levels. occurring beneficial species.

Organic Production Series— Insect Management 18 For more information about biological control Intercropping provides a way to keep the using insect predators and parasitoids, see beneficials close to crops and to provide them Pickett and Bugg, 1998; Barbosa, 1998; or with consistent sources of food and shelter. Landis et al. 2000 in the “Recommended Reading” list at the end of this chapter. An Many organic farms are already intercropped extensive discussion can be found at these to maximize land use and to suppress weeds. Web sites: Polycultures—diversely planted crop areas— • Michigan State University site: are common in tropical countries, but they are http://ipm.msu.edu/natural-enemies.htm. used very little in conventional agriculture in • Cornell University site: the United States because they do not fit well www.nysaes.cornell.edu/ent/biocontrol with mechanization. Some research information is available on how a polyculture Conserving Natural Enemies affects insect pests and their natural enemies. Proponents of polyculture cite the concept of Conservation biological control involves diverse stability as the basic ecological theory managing crops and surrounding vegetation for this approach: Diverse habitats are in a manner that encourages natural enemies considered more stable, so pest outbreaks are and their negative impacts on pest species. dampened. The thinking that underlies this This involves identifying anything that concept is this: If an agricultural system can suppresses the natural enemies and mimic a natural system with many different modifying agricultural fields and surrounding plants (and many trophic levels or levels of vegetation to provide habitats for them. food web relationships among organisms), it Manipulation of habitats extends to both crop will be better able to resist pests. and noncrop areas. In the crop area, intercropping can enhance biological control. Why Use Intercropping?

Intercropping. Keeping beneficial insects in The intercropping system should relay or and around annual crops may be achieved by transport predators and parasitoids from crop intercropping, which involves placing a crop to crop. The purpose is to present a continu- plant and another plant within close ous, attractive habitat for beneficial insects. proximity to promote insect interaction. It is one part of a comprehensive conservation Intercropping challenges. Several problems plan to manipulate habitats in ways that exist with the intercropping scenario. First, enhance natural control. The resources pest population levels in a polyculture may provided to natural enemies include pollen, stabilize, but at a level above the economic nectar, alternate prey or hosts. These threshold for the crop. Second, the evolution resources can considerably enhance biological of insect interactions cannot be over- control. Because annual crops are interrupted simplified in this manner. For example, many seasonally, they are not a continuous habitat. natural systems are functionally Therefore, survival of a pest insect’s natural monocultures. So the dampening mechanisms enemies depends on their success in finding that evolved under these conditions should the other habitat and prey they need to operate best in monocultures. It is more survive. When annual crops are planted, realistic to assume that some natural control beneficial insects must discover and invade agents are more effective in monocultures and the new crop. Unfortunately, beneficials are that some are more effective in polycultures. usually slower to recolonize than pest species. These reservations are not presented as

Organic Production Series— Insect Management 19 • The intercropping system should relay or arguments against polycultures but as a move predators and parasitoids from crop warning: Diverse agroecosystems must be to crop. carefully planned if the farmer’s objective is to • Its purpose is to present a continuous, maximize natural control of insects. attractive habitat for beneficial insects. Few guidelines have been developed to aid in This habitat rotation includes the crop the process of designing an intercropped needing protection. It will likely involve system. Research on the effect of planting the relay crops very early, intercropping on insect natural enemies is growing cover crops in the winter to very difficult due to the complexity of the maintain beneficial insects, or both. As work. For example, fewer pest species in a one crop begins to senesce or age, polyculture could mean there are more predators and parasitoids can exploit new predators and parasitoids, or that the crop is crop habitats. less attractive or less nutritious due to plant • Crop relaying should continue competition, or a combination of all of these. throughout the year. Uncoupling the impact of intercropping from • The plant combinations are important. the effects of surrounding vegetation (such as Different plants will support different woods and field margins) and unraveling the sizes of insect populations. So a weed- operating mechanisms are difficult tasks. corn intercrop will not have the same Nevertheless, some studies indicate that poly- insect populations as a bean-corn system. cultures may be an effective way to diversify agroecosystems. Often, all of the requirements for intercropping can be met simply by As a general rule, polycultures are a positive incorporating native vegetation strips within step toward pest control if carefully planned. cropping systems. Keeping the plants mowed For example, certain plants can serve as at specific times can encourage beneficial reservoirs for pest insects, such as thrips or insects to migrate to crop plants. This is an stink bugs. Observations from organic farms, easy and inexpensive way to try intercropping however, indicate that this tactic is successful to attract and conserve beneficials. Weedy enough that intercropping should be tried to species, however, are likely to dominate for determine possible benefits. The benefits and three to four years. And many growers are not problems associated with this strategy are enthusiastic about encouraging weeds very sitespecific. The pest situation, plant because another function of intercropping is combinations, weather, and other factors to suppress weeds. In this case, relay cropping make the final outcome of this approach will have to be used. Using this approach, an unpredictable. intercrop is planted in strips among the crop Intercropping design considerations. of interest so that when it senesces or is Polycultures are often thought of as a crop-to- mowed, the crop of interest will be able to crop combination (for example, beans and support natural control agents. This relaying corn). But they can also include natural- continues throughout the year. Relay vegetation-crop and living-mulch-crop cropping can also include planting into living mixtures. Some common objectives should be mulches that naturally die in time (such as considered when designing a polyculture: cereal rye or vetch).

Organic Production Series— Insect Management 20 The questions to ask when considering cover crop will have less effect on pest and intercropping are, “What plants?” and “When beneficial populations than disking or should they be planted?” Because there are plowing. Whether the cover is destroyed all at many possible answers, the most prudent once or in stages is another factor that plan is to introduce different species one at a influences the preservation of beneficials. time and judge the impact before moving to Mowing a cover crop to encourage beneficials more complex plant communities. to change habitat before disking will lessen mortality. Cover Crops. Cover crops are usually Field Borders and Hedgerows. Field planted to sequester soil nutrients, add borders and hedgerows represent an organic matter to the soil, prevent erosion, important component of the whole mosaic or and add nutrients. Cover crops can also combination of habitats occupied by beneficial provide food and habitat for beneficial insects. insects. It is unlikely that all the survival Insect natural enemies need food and shelter needs of beneficials will be met within field during the winter, and keeping them close to borders. Many beneficials will spend part of current or planned crops may help protect their time in field borders or hedgerows. newly planted crops. Cover crops can increase These areas also serve as corridors that the overall number of beneficial insects, and beneficials use to move from one field to beneficials can move from dying winter cover another. Some consideration of all these areas crops to spring-planted crops to provide some is needed to develop a complete plan for pest suppression. However, the kind of cover encouraging natural control. crop (whether it is crimson clover, cereal rye, vetch, or some other cover) appears to be Plants in hedgerows usually consist of natural important. Moreover, an increase in beneficial vegetation that, as much as practical, should insects does not always translate into a be preserved. Field borders, depending on general decrease in pest species or an increase how they are managed, usually consist of in yield. Each cover crop provides different annual plants. The natural complex of annual resources and habitats that may encourage plants may provide the habitat and resources some species and not others. Most often, cover needed by beneficial insects. Certain practices crops are selected for agronomic char- can help to maintain a desired mix of plants. acteristics and their ability to suppress weeds. For example, mowing at a particular time Their influence on insect natural enemies interval or height will stop the natural process should be a part of the evaluation process of succession to woody perennial vegetation. when deciding on specific crops. Some plans for maintaining plant mixtures The success of cover crops in preserving or should be made. Too often, borders are left encouraging beneficial insects depends in unattended until there is time to mow them. large part on how the cover crop is going to Some pest problems, such as mites, can be be destroyed or suppressed so that crops can spread by waiting until midsummer to mow. be planted. The frequency and intensity of Gather all the information that is available disturbance is important to the stability of about maintaining field borders before populations of pests and their natural deciding on a maintenance schedule. enemies. A cover crop that can be allowed to Arranging Crops. The physical arrangement die naturally so that beneficials have time to of crops in an area may affect biological find other habitat is preferable to a cover crop control. Beneficial insects often occupy the that must be managed all at once. Mowing a

Organic Production Series— Insect Management 21 ground under plants and the foliage. Tall- control of aphids. Many suppliers of growing plants may afford little cover or beneficial arthropods in the U.S. market moisture for ground-dwelling beneficials. predatory mites, greenhouse parasitoids and Similarly, foliage-dwelling beneficials spend predators, and general predators. For little time on the ground. Short crops example, the trichogramma wasp, a parasitoid intercropped with taller crops may encourage of insect eggs, is the most widely produced more interaction between these two groups and released arthropod used for and result in more robust natural control. augmentative biological control in commercial settings. These parasitoids are easy to rear, Augmenting Natural Enemies and they kill pest eggs before the hatched insects can cause injury. Trichogramma are Some insects that are natural enemies of pests commonly used in inundative releases. are produced and sold as pest treatments. For Careful planning is critical to the success of a organic pest management, this may be an natural enemies release program. There are important way to suppress damaging insects. three important considerations when using Obtaining the best possible outcome depends natural enemies: on understanding how to develop a successful • biological control program. The natural enemy selected should be correct for the specific situation and Augmentation involves adding something to specific pest. an agroecosystem to regulate pest population • The quality or viability of the product densities. It usually involves either mass purchased should be adequate. production of beneficials or genetic • The timing and rate of application should enhancement to improve their ability to be correct. survive negative influences. The most common example of augmentation is purchasing commercially available predators or parasitoids for release into greenhouses or commercial crop fields. If the natural enemy is released in large numbers (tens of thousands to hundreds of thousands), it is called an inundative release. If a few are released (hundreds to thousands) with the expectation they will reproduce and increase in number, then it is called an inoculative release.

Augmentation of natural enemies is probably the most widely recognized form of biological control. Commercial use of natural enemies is most developed in Europe, where farmers Figure 5. Releasing predators and parasitoids into commonly release natural enemies in greenhouse vegetable crops for pest management is a common practice. (Photo by Matt Miller, De- orchards, vineyards, and vegetable crops to partment of Entomology, N.C. State University.) manage pest species. Many farmers recognize that lady beetles are “good bugs” that eat “bad bugs” and purchase them for natural

Organic Production Series— Insect Management 22 Purchasing Natural Enemies. Buyer beware may be unknown, and no one can be sure is a good warning to remember when the product would work for a specific pest purchasing natural enemies. Dozens of problem. suppliers market insect natural enemies. Some • How many natural enemeies are received? may want to sell products that are not wanted This should be presented as an average, or needed. Some may not be able to provide plus or minus a range. With some natural the technical help that successful use of a enemies, only the female actually attacks biological control requires. Suppliers of the target pest. Find out if this is the case biological controls should maintain for any control agents being purchased professional standards, and a thorough and, if appropriate, be sure to find out the scientific analysis should be required for any number of females being shipped. product. • How vigorous is the material? For the batch of natural enemies from which a When selecting a supplier, asking the kinds of shipment is being made, it is fair to ask for questions suggested here may help identify measures of the average fecundity those that are reputable and reliable: (number of eggs laid), life span, and sex • Does the company provide professional ratio (percentage of females). In some consulting services to set up an IPM cases, it may be important to have specific program prior to selling natural enemies? information. For example, some parasitic This should include a thorough wasps, such as trichogramma wasps, can understanding of the pest situation and lose the ability to fly when reared for current crop management practices. many generations in insectary cultures. • Does the company provide detailed When purchasing this beneficial, ask the instructions on how to handle and apply supplier to provide the percentage of the natural enemies before they arrive? natural enemies with wings in the batch. • Does the product arrive by overnight Or, in the case of ladybeetles, ask the delivery in an insulated container that supplier to indicate the percentage in the may contain a cold pack? This will protect batch that are parasitized. Some natural enemies from temperature ladybeetles are simply scooped from extremes, and prevent some natural overwintering sites, and a substantial enemies from emerging prior to arrival. portion may be parasitized and die before they do any good in the field. The One important question to ask is this: Does supplier also should provide standard the company provide any measure of the values taken from an independent article quality of the natural enemies received? This in a scientific journal so that a buyer can question involves several quality determine if the count or ratio provided is considerations: adequate and make informed • Does the company tell exactly what comparisons. species will be shipped and who made the • How many natural enemies will actually species determination? This determination emerge alive once they are introduced should have been made by a recognized into the crop? The supplier should taxonomic expert, not necessarily provide a method for determining how someone at the company. The species many natural enemies actually emerge in name should be a double Latin name, for the field. This can be very important example: Encarsia formosa. If the name because it is the only way to determine the appeared as Encarsia sp., then the species actual rate of product applied.

Organic Production Series— Insect Management 23 • Does the company offer reasonable Timing of releases or applications. The solutions for any difficulties timing of natural enemy releases is critical to encountered? Does it follow up to the success of biological control. Because determine success or failure? natural enemies work better as preventives

rather than as pest management cures, it is Names, addresses, and telephone numbers of important to release them when pest suppliers can be obtained from these sources: infestations are just beginning. Sampling Bio Integral Resource Center methods and materials for specific pests are P.O. Box 7414 often readily available from suppliers. Berkeley, CA 94707 Some natural enemies are affected by the www.birc.org season, and they can be less effective as a Association of Natural Biocontrol Producers result. The time of day of release can also be www.anbp.org important. When the temperature is high during the middle of the day, natural enemies tend to be more active and may disperse or

leave the area where released. Higher Handling and Releasing Natural temperatures during the release can cause Enemies. A supplier should provide specific increased mortality of the beneficials, handling instructions prior to or at the time reducing the number available to attack pests. the natural enemy shipment arrives, and the Other weather conditions, especially rain, instructions should be followed carefully. may also have an impact on natural enemy Many natural enemies are tiny insects and survival during release. As a general rule, mites. They should be kept under relatively releases should be made in a cool part of the cool conditions (at room temperature) and out day (early or late), under favorable weather of direct sunlight. If the beneficials arrived in conditions, and at a time of year that the an insulated container, they should probably specific natural enemy finds favorable. be kept there until time for release. Usually, Suppliers can and should provide this the sooner the beneficials can be released after information. arrival, the better. For example, some If a reliable and knowledgeable supplier of predatory mites are shipped with a small food natural enemies has been selected, then the supply. Once that food is exhausted, they feed quality of material received should be on one another or starve. consistently high. However, some factors, How many to release. Suppliers should such as shipping conditions, are out of a provide detailed instructions regarding the supplier’s control. It may be helpful to work application “rate” for the natural enemies with suppliers to develop a quality-assurance supplied. Usually this is expressed as a protocol. The condition of the natural enemies number of natural enemies per given “unit,” when they are received can have a dramatic such as a number of natural enemies per effect on the results. infested leaf, plant, square-foot, or acre. The Environmental conditions in the release recommended rate should be followed very area. Like all living organisms, natural closely. Any questions that may arise enemies have specific requirements and limits regarding application numbers can be for survival. The conditions present in the directed to the supplier. area where the natural enemies will be

Organic Production Series— Insect Management 24 released should be considered before making Evaluating Control Efforts with Natural a release. For example, some species of Enemies predatory mites will perform better under hot, dry conditions, whereas others will To determine the success of a biological perform better under cool, humid conditions. control program, develop a strict set of Light can also have a dramatic impact on conditions in the planning stage before the natural enemies. For example, the mealy-bug program starts. Program success will be easier destroyer beetle will slow or stop its to determine if there is at least one pair of reproduction, feeding, and growth if treated versus untreated areas. Use natural supplemental lighting is not sufficient in enemies only in the treated plot(s). The winter months. If releasing a mobile stage of a untreated plot(s) should not receive natural natural enemy (for example, adults that can enemies. The treated and untreated plots fly) it may sometimes be advisable to cage the should be far enough apart to avoid natural enemies on infested plants for a day dispersion of natural enemies from a treated or two to allow them to become accustomed to an untreated plot. The supplier can help to their new surroundings. The presence of determine how to do this. pest insects will also encourage reproduction Define what measurements to take in the and reduce the likelihood that the beneficials plots. These are some examples of useful will leave the area. In some cases, the information: presence of nectar-bearing plants or other • food sources (such as aphid honeydew) may The density (number per plant or feet of also encourage natural enemy populations. row) of the damaging stage of the pest before and after treatment. Remember Insecticide use may be the most important that natural enemies usually require time consideration when including natural enemies to be effective. in a pest management program. Spraying for • The percentage of natural enemies that pests other than those being targeted by actually were released. natural enemy releases may interfere with or • The percentage of the target pest eliminate the natural enemies. Care should be population that is parasitized (if the taken to avoid spraying materials harmful to beneficial released was a parasitoid). natural enemies directly before, during, and • The level of pest damage. after release. If spraying must be conducted, it • The final yield. is important to find out which pesticides have the least effect on natural enemies. Developing a Biological Control Plan: When Encouraging natural enemies after their Are Natural Enemy Releases Appropriate? release. Following a release of natural As with other pest management methods, the enemies, it is extremely important to make success or failure of biological control will be sure that sufficient numbers have been determined by the population levels of pests established to control a pest problem. when natural enemies are applied. For example, Scouting procedures used to monitor for pest if a pest population level is too high, the natural populations can be modified to monitor enemies released may not be able to act quickly natural enemy populations as well. enough to protect crops. In this case, an

Organic Production Series— Insect Management 25 insecticide application may be needed prior to A producer must know which organic the introduction of natural enemies. pesticides are allowable, what materials are labeled for their crops, and the efficacy of If, on the other hand, the pest population is very those materials against the intended target small, then naturally occurring enemies may pests. Pest control materials are classified as already be present. Another approach to take in allowable, restricted, or prohibited for use in this case might be to treat only infested areas organic systems. To avoid the risk of losing with insecticide, rather than spending the time organic certification, make certain you know and money to treat the entire crop. if and under what circumstances the material that you are planning to use is allowed. Usually, natural enemies work best as a Examples of types of materials that are preventive pest management method. That is, currently allowed in organic production they should be introduced into a crop before an include allowable formulations of insecticidal economically damaging pest infestation begins. soap, diatomaceous earth, potassium or If pests reach economically damaging levels sodium bicarbonate, spinosad, various before the release of natural enemies, successful microbials, bentonite and kaolinite particle control is not likely. This means that pest films, plant extracts and oils, and problems must be anticipated by carefully pheromones. Some products with allowable monitoring pest populations so that the active ingredients may contain unacceptable response can be planned and timed correctly. adjuvants, so it is important to check the label Well-established monitoring or sampling and with your certifying agency before using a record-keeping methods have been developed material. for a wide variety of pest and crop situations. Some types of materials that are restricted in

organic production include dormant and summer oils (narrow-range petroleum, fish, INSECTICIDES and plant oils), sulfur compounds, copper compounds, and botanical pesticides. When nonchemical practices documented in Examples of materials that are NOT allowed the Organic System Plan are not sufficient to in organic production include: transgenic prevent or control populations of insect pests crops; synthetic insecticides and miticides, from rising above a level that is economically unless specifically allowed on the National damaging, a biological or botanical material List; heavy-metal-based pesticides, such as or a substance included on the national list of arsenates and lead; synthetic wetting agents; synthetic substances allowed for use in nicotine sulfate and other tobacco products; organic crop production may be applied to strychnine; and some botanicals. prevent, suppress, or control pests. The National List of Allowed and Prohibited The conditions for using the allowable Substances provides information on allowed material or substance must be documented in and prohibited synthetic and nonsynthetic the Organic System Plan. The producer substances for organic crop and livestock should have a plan for how and when they production: will react to an insect pest outbreak with an http://www.ams.usda.gov/nop/NationalList/ allowable substance. In all cases, if you have ListHome.html any questions as to whether a material is

Organic Production Series— Insect Management 26 unacceptable level of damage may differ allowable or not, you should check with your in direct, wholesale, and retail markets. organic certification agency to determine if • Total control may not be necessary. Just specific materials are allowed, restricted, or slowing the rate of pest population in- prohibited in your organic system. Use of a crease may be sufficient to allow natural nonallowed substance can result in the loss of control to provide suppression. certification and the need to re-transition the • Repeat applications may be necessary if affected land for 36 months. total control is needed. • Unusual pests may become more of a The decision to employ an insecticide in problem. Wide-spectrum insecticides organic systems, even if it is an allowed often keep species other than the target material, is difficult for several reasons: pests under control. Narrow-spectrum • Insecticides may disrupt a balance biological insecticides may allow these between beneficial and pest species, other pests to flourish. making the original problem worse or • Beneficial species can be negatively causing secondary pest outbreaks. affected by organic insecticides. • Most organic insecticides are expensive to In view of these issues, these use guidelines use. should be followed: • Insecticides represent a temporary solution. This is the most important • Use insecticides selectively, as unintended consideration: Without more permanent effects can lead to using more insecticides. interventions, the same species is likely to • Use insecticides with the least negative cause problems regularly. consequences. For example, Bacillus thuringiensis insecticides, which are toxic to a relatively narrow range of pests, will Insecticides approved for use in organic have the potential to cause far fewer systems can be less efficacious than problems than products that are toxic to a insecticides available for use in nonorganic broader range of pests. systems, so trying to determine if the control • Use rates and application methods that delivered is worth the cost can be a difficult correspond to the size of the crop plant. decision. In many cases, the degree of success Small plants can be more easily covered will be site specific. Usually only after an than large plants. A large, dense plant insecticide has been used several times under may require an increase in insecticide rate, various conditions is it possible to reach a full application volume and pressure, or all of appreciation of what a particular product will these. deliver. Before using any insecticide, a farmer • Consider environmental conditions that should consider the following issues: can affect the efficacy of an insecticide. • Determine if the insecticide that you Conditions such as temperature, intend to use is allowable in organic humidity, sunlight, and rainfall or systems. The use of some insecticides, irrigation can all affect how long organic even if allowed, is restricted. Check with insecticides are able to protect plant your certifier to determine under what surfaces. Usually, the greater the conditions the insecticide may be used. environmental extremes, the shorter the • Consider the level of insect damage that is period of protection. Never spray during acceptable to your market. What is an the hottest part of the day (in the

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afternoon). Apply dusts only when plants are dry. Inorganic Insecticides • Observe recommended harvest intervals for organic insecticides. Read and follow Diatomaceous Earth. This is a restricted all label instructions. material that can be used as a pest lure, • Follow mixing and application repellent, or as part of a trap, or as a disease instructions exactly. control. It may be used for other pesticidal • Use all pesticides carefully. They can be purposes only if nonchemical practices toxic or irritating to humans and animals. documented in the Organic System Plan are Follow label guidelines on safe insufficient to prevent or control insect pests. application, including necessary This product, which is silicon dioxide, is the protective clothing or gear. Some are very finely milled fossilized remains of single- toxic and can have negative nontarget or celled organisms (diatoms). The milling off-site effects. process produces a glass-like product that can

scratch an insect’s exoskeleton or puncture Organic Insecticides gut linings. When used as a desiccant, it is dusted or placed around plants to be Historically, conventional insecticides have protected. The dust scratches away the thin, not been approved for use in certified organic waxy, waterproof layer on the exterior of systems. Recently, however, some companies insects, making them less tolerant of that manufacture and sell agricultural environmental conditions. Care should be chemicals have been using active ingredients taken to protect workers from the dust from natural sources. An example is the generated during mixing and application. insecticide spinosad. Spinosad is a Kaolin. This is a naturally occurring clay fermentation product of the soil-dwelling resulting from the weathering of aluminous actinomycete Saccharopolyspora spinosa. minerals with kaolinite as their prinipcal incredient, such as feldsspar. Kaolin is ground There are commercially available to a uniform particle size for application as a formulations of spinosad insecticides plant protectant applied as a water allowable for use in organic systems. suspension to plant parts. This material has Allowable formulations of spinosad will demonstrated efficacy for both insect and provide excellent control of many caterpillar disease control. Kaolin controls insects by species, but they are less efficacious on making the protected plant unattractive piercing-sucking insects (such as stinkbugs because it leaves a white film on leaves. The and plant bugs). Formulations of spinosad are white film may interfere with the insect’s host labeled for a wide array of vegetables—for finding. It also acts as a physical barrier example, potatoes, eggplant, tomatoes, preventing insects from reaching vulnerable cucurbits (melons, cucumbers, pumpkins, parts, and acts as a repellent by crerating an squash), cole crops, and sweet corn, as well as unsuitable surface for feeding or egg-laying. some field crops (such as peanuts). Spinosad The particles also cling to insects and make controls Colorado potato beetle larvae. their normal activities more difficult. It has Farmers should consult local Extension proven highly effective for some pest species specialists for specific applications and follow and less for others. In regions with high light label instructions.

Organic Production Series— Insect Management 28 and temperature levels, kaolin also acts as an farmers can prevent phytotoxicity by paying antitranspirant, reducing plant stress and careful attention to rate, method, and timing sunburn. Care should be taken to protect of application. It is a good idea to test a small workers from the dust generated during sample of a summer oil for both phytotoxicity mixing and application. Local and efficacy before applying it to an entire recommendations should be followed. crop area. Dormant oils are restricted-use materials. As the name implies, dormant oils Sulfur. Elemental sulfur is a restricted use are used in the winter when plants are not material that may be used for pesticidal growing. The timing of application can be purposes only if nonchemical practices critical as some insect life stages are documented in the Organic System Plan are unaffected by dormant oils. insufficient to prevent or control insect pests. This product is applied as a finely ground Plant and fish oils are long-chain hydrocarbon powder or spray for control of spider mites. It lipids that include fatty acids, some alcohols, must be used carefully or it can burn foliage. glycerides, and sterols. Plant oils are derived from seeds, whereas fish oils are byproducts Insecticidal Oils of the fish processing industry. Essential plant oils, including mixtures of wintergreen, clove, Oils kill insects and mites by smothering eggs and rosemary, are generally derived from or adults. Oil products can control a wide stems and leaves rather than seeds. Plant and range of soft-bodied insects, such as aphids, fish-derived oils are also used as spreader- mites, thrips, and whiteflies. stickers, surfactants, emulsifiers, and carriers. Such oils may not contain synthetic pesticides. Narrow-range (median boiling points 415 – Plant and fish oils are becoming more 440º F) insecticidal oils are highly refined available than in the past, and they show petroleum oils and are restricted use promise for mite control. Recent tests have materials. Narrow-range oils may be used for demonstrated that these oils are effective on pesticidal purposes only if nonchemical plant-eating mites and less harmful to practices documented in the Organic System predaceous mites. Plan are insufficient to prevent or control insect pests. Petroleum derivatives outside the Follow label recommendations to reduce the narrow range are prohibited in organic risk of phytotoxicity of insecticidal oils. production. Oils have become more widely Conditions that slow evaporation increase the used in crop production as new refining risk of phytotoxicity. Crops vary in their methods have made it possible to make oils sensitivity, and oils are incompatible with less phytotoxic to plants. They still must be sulfur and copper on some crops. used carefully to avoid foliage burn. Allowed oils also can be derived from vegetable and Insecticidal Soaps fish sources. Approved products must not contain any prohibited inert ingredients. Insecticidal soaps are restricted-use materials that may be used for pesticidal purposes only Oils are classified as summer oils and dormant if nonchemical practices documented in the oils. Summer oil is usually used as a 0.5 to 3 Organic System Plan are insufficient to percent finished solution. Because this prevent or control insect pests. Soaps or fatty material is used during the growing season, acid salts are manmade fatty acids that are

Organic Production Series— Insect Management 29 used to control soft-bodied pests like aphids and different midgut environments within and mites. species. Bt toxins have a third name associated with them to differentiate the Insecticidal soaps work by smothering soft- various strains. For example, Bt kurstaki and bodied insects and disrupting their cuticle Bt aizawai are more active on caterpillars and layer. Soaps do not have residual activity and worms, whereas Bt tenebrionis and Bt san diego do not provide lasting control. They are work better on beetle pests. For this reason, it effective only on contact, so thorough is very important to match the product with coverage of the infested area is critical to the target pest. success. Soap products are most effective when they dry slowly. Once dry on the plant Even within strains that demonstrate activity surface, they are not effective againsts insects on similar insect groups, there can be and mites. Soaps are not effective against differences in control among species. For insect eggs. example, Bt aizawai is more active than Bt kurstaki on army worms. Some weaknesses of Phytotoxicity can be a concern with soap these products must be considered before use: products, and crops vary in their sensitivity. • Bt products have a short residual period Test effectiveness and phytotoxicity before because the ultraviolet radiation in spraying a large area. sunlight breaks down the toxin. Farmers traditionally have extended residual Microbial Insecticides effectiveness by spraying just before dark. • Timing of application should be matched Bacillus thuringiensis (Bt). This product to the pest’s feeding habits. Bt must be contains a bacteroa; toxin that kills insects. It consumed to work. An insect that hatches, is derived from a naturally occurring soil feeds for a short time, and then bores into bacterium and is harmless to other animals, the plant or fruit will probably not ingest including man. Bt must be ingested to work. enough toxin to be affected. For boring After the bacterium is eaten, the toxin causes insects, applications must be made at or midgut paralysis in insects, which stops their just before egg laying and thoroughly feeding, usually within 24 hours. Next, the cover the plant. midgut lining is perforated, allowing leakage between the gut and the insect body cavity. In recent years, Bt products and plant The insect dies in two to four days. Bt will not varieties genetically modified to express Bt kill other pests, such as aphids, mites, or toxins have been relied upon to control pest thrips. Not all formulations of Bt are allowed species that are resistant to conventional in organic production. Check with your insecticides, and some pests have developed certifier to determine which formulations are resistance to Bt. The diamondback moth is an currently allowed. example of a pest with Bt resistance. Farmers should be very watchful when using Bt on Thousands of Bt strains have been discovered vegetable pests to be sure that they are and usually have more activity on specific achieving the desired control, especially if groups of insects—beetles, caterpillars and their farms are surrounded by land where worms, or flies and mosquitoes. This varying conventional vegetable production occurs. toxicity is apparently due to different toxins Even if a farmer has used Bt very little in the

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past, highly mobile resistant adults can immigrate into their crops from nearby farms, Some botanicals, however, are very toxic to leading to control failures. fish, other wildlife, and humans. Some have potential user and off-site problems that Beauveria bassiana. This common insect- require careful safety precautions. The pathogenic soil fungus has been formulated botanical insecticide rotetone is prohbited for into an insecticidal product. Fungal use in organic systems. Petitions have been insecticides have two advantages. First, they made to the National Organic Program to are contact insecticides. The insect does not prohibit the use of other botanicals. Always have to ingest them to become infected. check with your certifier to determine if the Spores land on an insect, germinate, and botanical pesticide that you plan to use is penetrate the exoskeleton. Once inside, the allowed. fungus proliferates, adsorbs nutrients, and Contact Botanicals. All of the contact emits toxic compounds. After the insect is insecticides are nerve poisons that cause dead, the fungus grows out to the surface of insects to stop feeding and die quickly. the exoskeleton and forms millions of spores. Second, fungi can initiate an epizootic (a Pyrethrum. This is the generic name of a widespread, self-sustaining disease of insects) plant-based insecticide derived from the which can be very effective at controlling powdered flowers of a chrysanthemum insects at high population levels. Beauveria species. Synthetic pyrethroids are not allowed has been formulated into several in organic production. Most pyrethrum is commerically available products to control imported from Africa. It is a contact poison insects, such as aphids, whiteflys, thrips, that acts quickly as a “knockdown.” mealybugs, mites, and various caterpillars. Pyrethrum is a broad-spectrum insecticide These products are sold under different that used against true bugs, caterpilars, tradenames, such as BotaniGard, Naturalis, beetles, aphids, flies, whiteflies, thrips, and Mycotrol. leafhoppers, and mites. Some insects may be able to recover after the initial knockdown if Botanical Insecticides the dose is too low. Pyrethrum is highly toxic to honeybees, other beneficial insects, and Botanical insecticides are made from plants fish, and moderately toxic to birds. Pyrethrin that have insecticidal properties. Botanical degrades rapidly and offers little residual insecticides are restricted-use materials. They control. may be used for pesticidal purposals only if nonchemical practices documented in the Synergists, such as piperonyl butoxide (PBO), Organic System Plan are insufficient to are often added to pyrethrum products. PBO prevent or control pests. These materials have is not allowed in organic production. Care several common characteristics: should be taken to avoid products that contain synergists and additives not allowed • They are broad spectrum insecticides. in organic production. Check with your • They break down rapidly in the certifier to determine if the product that you environment and so provide little, if any, plan to use is allowed residual control. • They are less toxic to mammals than Citrus oils (d-limonene, l-limonene) are synthetic insecticides in most, but not all, extracts from citrus peels and are usually cases. combined with soaps as contact poisons

Organic Production Series— Insect Management 31 Ryania comes from the stems of a tropical against soft-bodied insects and mites. This plant. It does not kill quickly, but it can cause material works only on contact and will pests to stop feeding relatively quickly. provide no residual control. Ryania can be effective at controlling Other Botanical Insecticides. These caterpillars and some thrips. It should be botanicals act to poison insects through their tested on a small scale before use because it is digestive systems or to repel insects with ineffective on some species. It is considered strong odors and tastes. Some interrupt life slightly toxic to mammals. cycle stages with hormone-like substances. Sabadilla comes from a South American lily. Always check with your certifier to determine It is not acutely toxic to mammals but must be if the botanical pesticide that you plan to use carefully used because it is a powerful irritant is allowed. and, if inhaled, may result in circulatory and Neem (nonsynthetic extracts and derivatives) respiratory problems. It may be used in a is a restricted material that can be used as a spray or dust and acts as a contact material, pest lure, repellent, or as part of a trap, or as a but it has some activity as a stomach poison. disease control. It may be used for other Sabadilla has some activity on the group of pesticidal purposes only if nonchemical insects known as the true bugs. True bugs are practices documented in the Organic System insects in the order Heteroptera that have two Plan are insufficient to prevent or control pairs of wings and needle-like mouthparts for insect pests. Neem products are derived from sucking fluids from plants (squash bugs, for the seeds of the neem tree, Azadiracta indica, example). This material deteriorates rapidly grown from India to Africa. when exposed to light, so it offers little or no residual control. Always check with your Neem products have been used extensively certifier to detemine if the botanical pesticide for insect control in tropical countries in field that you plan to use is allowed. crops and in stored products. Chemically, neem mimics certain insect hormones used to Garlic barrier is an oil extracted from garlic. It control metamorphosis. Neem interrupts this is intended as a repellent for a wide variety of process and the insect dies. It is also effective insects. Efficacy tests have resulted in highly as a repellent and stomach poison. Some variable control. This product should be residual activity can be expected. Neem extensively tested before depending on it for products are generally formulated as control. emulsifiable concentrates. Follow label directions for specific application guidelines Other Control Approaches and re-entry and pre-harvest intervals. Neem extracts have been shown to affect a broad Chitin. Chitin is a material that makes up the range of insects, but efficacy varies among exoskeleton of arthropods (insects and species. Used alone or in combination with crustaceans) and nematodes. Chitin is a Bacillus thuringiensis or pyrethrum it has restricted use pesticide, and may be used as a provided satisfactory control of resistant pest lure, repellant, or as part of a trap or for pests, such as cabbage loopers and other pesticideal purposes, such as diamondback moths. Thrips and whiteflies nematicidal purposes only if non-chemical may also be controlled. practices documented in the Organic System

Organic Production Series— Insect Management 32 Biological Control: A Guide to Natural Enemies Plan are insufficient to prevent or control in North America. insect pests. Only products derived from http://www.nysaes.cornell.edu/ent/ nonsynthetic sources may be used. Use of biocontrol/ chitosan, a polysaccharide obtained by de- Enhancing Beneficial Insects with Native Plants. acetylation of chitin, is prohibited. When http://www.nativeplants.msu.edu/ chitin is added to the soil, microbes produce Identifying Natural Enemies. toxins (forms of ammonia), digestive enzymes http://ipm.msu.edu/natural-enemies.htm that destroy the cuticles of insect and Manage Insects on Your Farm: A Guide to nematode pests, or both. Field tests of efficacy Ecological Strategies. have not been consistent. http://www.sare.org/publications/insect/ind ex.htm Home Remedies. Bug juices made from National Organic Program. www.ams.usda. insects blended into a liquid and sprayed on gov/nop/ crops have been the subjects of much Resource Guide for Organic Insect and Disease anecdotal information. Very few of these Management. materials have been scientifically tested. Any http://www.nysaes.cornell.edu/pp/resource of these approaches should be tested on a guide/ small area until they have been thoroughly examined. Consult with your certifier to determine if your proposed method is Additional Reading allowable. Altre, J., E. Grafius, J. Sirota, E. Eliason, and B. Scriber. 1994. Colorado potato beetle control RECOMMENDED READING with biorationals, 1993. Arth. Mgmt. Tests. Ent. Soc. Amer. 19:108. Bartels, D. W., P. C. Bolin, and W. D. Hutchison. Sources Cited 1996. Microbial and insecticidal control of Barbosa, P., Ed. 1998. Conservation biological lepidopteran pests in Minnesota cabbage, control. Acad. Press. San Diego, Calif. 1995. Arth. Mgmt. Tests. Ent. Soc. Amer: Bugg, R. L. and C. H. Pickett. 1998. Introduction: 21:89. Enhancing biological control—Habitat Bird, G. W., T. Edens, F. Drummond, and E. management to promote natural enemies of Groden. 1990. Design of pest management agricultural pests. pp. 1-23. In enhancing systems for sustainable agriculture. In biological control: Habitat management to Sustainable Agriculture in Temperate Zones. C. promote natural enemies of agricultural pests. A. Francis, C. B. Flora, and L. D. King, eds. Univ. Calif. Press. John Wiley & Sons, Inc. Landis D.A., S. D. Wratten, and G. M. Gurr. Boucher, J. and G. Nixon. 1997. Evaluation of 2000. Habitat management to conserve mechanical control and alternative insec- natural enemies of arthropod pests in ag- ticides for managing squash vine borer on riculture. Ann. Rev. Ent. 45: 175-201. summer squash, 1996. Arth. Mgmt. Tests. Ent. Soc. Amer. 22:167. Boucher, J. and G. Nixon. 1996. Evaluation of On-Line Resources alternative insecticides for squash vine borer control on summer squash, 1995. Arth. Biointensive Integrated Pest Management (IPM). Mgmt. Tests. Ent. Soc. Amer: 21:175. http://attra.ncat.org/attra-pub/ipm.html

Organic Production Series— Insect Management 33 Boucher, J. R. Adams, G. Nixon, and J. Clark. Hoy, C. W. and M. J. Dunlap.1996. Control of 1995. Evaluation of insecticides for squash cabbage looper, diamondback moth and vine borer control on summer squash, 1993. imported cabbageworm on cabbage with Arth. Mgmt. Tests. Ent. Soc. Amer: 20:131. microbial insecticides, 1996. Arth. Mgmt. Carson, W. G. and J. T. Trumble. 1997. Impact of Tests. Ent. Soc. Amer: 22:94. insecticides on tomato insects, 1996. Arth. Ignoffo, C. M. 1992. Environmental factors Mgmt. Tests. Ent. Soc. Amer: 22:174. affecting persistence of entomopathogens. Chalfant, R. B. 1997. Control of lepidopterous Fla. Ent. 75:516-525. pests, 1992. Arth. Mgmt. Tests. Ent. Soc. Kerns, D. L. and T. Tellez. 1997. Control of Amer. 22:89. lepidopterous larvae on lettuce with garlic, Cranshaw, W. D. C. Sclar, A. Spriggs, and J. 1996. Arth. Mgmt. Tests. Ent. Soc. Amer. Bishop. 1996. Flea beetle control on broccoli, 22:135. Ft. Collins, CO, 1995. Arth. Mgmt. Tests. Knowles, B. H. 1994. Mechanism of action of Ent. Soc. Amer. 21:86. Bacillus thuringiensis insecticidal delta-en- Cranshaw, W. D. and F. C. Schwessing. 1996. dotoxins. In Advances in Insect Physiology, Squash bug control by basal stem treat- Volume 24, pp.275-308. Academic Press, ments, Rocky Ford, Co., 1995. Arth. Mgmt. London. Tests. Ent. Soc. Amer. 21:174. Linduska, J. J. M. Ross, K. Mulford, and J. Not- Cranshaw, W.,D. Patrick, L.Rice, and D. Cooper. tingham. 1995. Colorado potato beetle 1995. Control of Western black flea beetle on control on potatoes with microbial insec- cabbage, Ft. Collins, CO 1990. Arth. Mgmt. ticides, 1994. Arth. Mgmt. Tests. Ent. Soc. Tests. Ent. Soc. Amer. 20:70. Amer. 20:117. Cranshaw, W. and F. Schweissing. 1995. Corn Liu, T. X, J. M. Conner, and P. A. Stansly. 1997. earworm control, Rocky Ford, 1990. Arth. Use of Beauveria bassiana, an ento- Mgmt. Tests. Ent. Soc. Amer. 20:85. mopathogen, to control nymphs of Bemisia Edelson, J. V. and M. Peters.1997. Control of argentifolii under field conditions, 1995. lepidopterous pests on collards, 1996. Arth. Arth. Mgmt. Tests. Ent. Soc. Amer: 22:133. Mgmt. Tests. Ent. Soc. Amer. 22:119. Marutani, M. and E. Rivera. 1996. Control of Edelson, J. V. and M. Peters. 1997. Control of silverleaf whitefly on tomato, 1995. Arth. aphids on spinach, 1996. Arth. Mgmt. Tests. Mgmt. Tests. Ent. Soc. Amer. 21: 182. Ent. Soc. Amer. 22:165. Mau, R.F.L, L.R. Gusukuma-Minuto, K. Dart, Flint, H. M., N. J. Parks, J. E. Holmes, J. A. Jones, and R. S. Shimabuku. 1997. Evaluation of and C. M. Higuera. 1995. Tests of garlic oil Bacillus thruingiensis against DBM, 1994. for control of the silverleaf whitefly, Bemisia Arth. Mgmt. Tests. Ent. Soc. Amer: 22:103. argentifolii Bellows and Perring (Homoptera: Minzenmayer, R. and T. Fuchs. 1994. Insecti- Aleyrodidae) in cotton. Southwest. Ent. cides for control of aphids in cotton—1994. 20:137-150. Results demonstration report. Texas Ag. Ext. Gerace, D., D. C. Sclar, and W. Cranshaw. 1997. Serv. Texas A&M Univ. Control of onion thrips using Beauveria Noetzel, D. M., J. Miller, and C. Holen. 1996. bassiana formulations, 1996. Arth. Mgmt. Arth. Mgmt. Tests. Ent. Soc. Amer. 21. 152. Tests. Ent. Soc. Amer: 22:144. Palmer, C. R. and J. F. Walgenbach. 1996. Hazzard, R. V. and M. A. Mazzola. 1997. Foliar Insect control on staked tomatoes, 1995. sprays of Bacillus thuringiensis in early corn, Arth. Mgmt. Tests. Ent. Soc. Amer: 21:183. 1996. Arth. Mgmt. Tests. Ent. Soc. Amer: Palumbo, J. C.1997. Evaluations of selective 22:122. insecticides for control of lepidopterous Hoy, C. W. and M. J. Dunlap.1997. Control of larvae in lettuce. Arth. Mgmt. Tests. Ent. lepidoptera on cabbage, 1995. Arth. Mgmt. Soc. Amer. 22:136. Tests. Ent. Soc. Amer: 21:91.

Organic Production Series— Insect Management 34 Peters, M. R. and J. V. Edelson. 1996. Control of Shamyeh, N. B. and R. A. Straw.1997. Control of lepidopterous larvae on tomatoes, summer, lepidopterous insects on cabbage, 1996. 1995. Arth. Mgmt. Tests. Ent. Soc. Amer: Arth. Mgmt. Tests. Ent. Soc. Amer: 22:107. 21:184. Shelton, A. M. and W. T. Wilsey. 1997. Control Pickett, C. H. and R. L. Bugg, eds. 1998. En- of lepidopterous insects on corn with foliar hancing biological control: Habitat man- applications, 1996. Arth. Mgmt. Tests. Ent. agement to promote natural enemies of Soc. Amer: 22:124. agricultural pests. Univ. Calif. Press. Siegel, J. P. 2001. The mammalian safety of Prostak, D. J. 1994. Foliar sprays to control fall Bacillus thuringiensis-based insecticides. Jour. armyworm on late planted sweet corn, 1993. Inv. Path. 77(1):13-21. Arth. Mgmt. Tests. Ent. Soc. Amer. 19:92. Slocombe, A. C. and D. N. Ferro. 1995. Potato Prostak, D. J. 1994. Insecticidal, biological, and insect control, 1994. Arth. Mgmt. Tests. Ent. botanical control with foliar sprays for Soc. Amer. 20:122. whorl-infesting insects in sweet corn, 1993. Slocombe, A. C. and D. N. Ferro. 1995. Potato Arth. Mgmt. Tests. Ent. Soc. Amer. 19:92. insect control. 1994. Arth. Mgmt. Tests. Ent. Prostak, D. J. 1995. Control of fall armyworm in Soc. Amer. 20:120. whorl-stage corn using botanical foliar Sorensen, K. A. and C. W. Holloway. 1997. sprays, 1994. Arth. Mgmt. Tests. Ent. Soc. Control of lepidopterous larvae with in- Amer. 20:88. secticides, 1996. Arth. Mgmt. Tests. Ent. Soc. Prostak, D. J. 1995. Foliar sprays to control Amer: 22:110. European corn borer and fall armyworm on Sorensen, K. A. and C. W. Holloway. 1994. sweet corn, 1994. Arth. Mgmt. Tests. Ent. Cabbage looper control, Johnston Co., 1993. Soc. Amer. 20:87. Arth. Mgmt. Tests. Ent. Soc. Amer. 19:85. Prostak, D. J. 1995. Using garlic and seaweed Speece, J. 1996. Use of biorational and standard extracts to deter European corn borer and insecticides to control insects in potatoes, fall armyworm on whorl stage sweet corn. 1995. Arth. Mgmt. Tests. Ent. Soc. Amer: Arth. Mgmt. Tests. Ent. Soc. Amer. 20:88. 21:162. Rummel, D. R., S. C. Carroll, P. W. Kidd, M. D. Stansly, P. A. and J. M Conner. 1995. Control of Arnold, and K. C. Neece. 1995. Evaluation of diamondback moth and cross-striped organic and biological materials for control cabbageworm on cabbage. Arth. Mgmt. of the boll weevil. Report to the Texas Boll Tests. Ent. Soc. Amer. 20:80. Weevil Eradication Foundation. Texas A & Stansly, P. A. and M. Conner. 1997. Control of M Univ. 17p. southern armyworm, Spodoptera eridania in Schuster, D. J. 1997. Evaluation of biorational staked tomatoes, 1995. Arth. Mgmt. Tests. pesticides for management of the silver-leaf Ent. Soc. Amer. 22:186. whitefly on fresh market tomatoes, Spring Stansly, P. A. and B. M. Cawley. 1995. Control of 1994. Arth. Mgmt. Tests. Ent. Soc. Amer: sweetpotato whitefly, gemnivirus 22:179.. transmission, tomato pinworm, and leaf- Schuster, D. J. 1997. Control of armyworm and miner on staked tomato, spring 1991. Arth. pepper weevil on bell pepper, 1995. Arth. Mgmt. Tests. Ent. Soc. Amer: 21:139. Mgmt. Tests. Ent. Soc. Amer: 22:149. Stoltz, R. L. 1996. Colorado potato beetle control Schuster, D. J. 1995. Control of armyworms on with foliar sprays II, 1995. Arth. Mgmt. bell pepper in west-central Florida, fall 1993. Tests. Ent. Soc. Amer: 21:169. Arth. Mgmt. Tests. Ent. Soc. Amer. 20:103. Walgenbach, J. F. and C. R. Palmer. 1997. Schuster, D. J. 1995. Control of insects on fresh Control of lepidoperous insects on cabbage, market tomatoes in west-central Florida, 1996. Arth. Mgmt. Tests. Ent. Soc. Amer: spring 1994. Arth. Mgmt. Tests. Ent. Soc. 22:114. Amer: 20:134.

Organic Production Series— Insect Management 35 Walgenbach, J. F. and C. R. Palmer. 1995. Weisz, R., Z. Smilowitz, and B. Christ. 1994. Control of lepidoperous insects on cabbage, Distance, rotation, and border crops affect 1994. Arth. Mgmt. Tests. Ent. Soc. Amer: Colorado potato beetle (Coleoptera: Chry- 20:81. somelidae) colonization and population Walgenbach, J. F. and C. R. Palmer. 1995. density and early blight (Alternaria solani) Control of lepidoperous insects on cabbage, severity in rotated potato fields. J. Econ. 1993. Arth. Mgmt. Tests. Ent. Soc. Amer: Entomol. 87(3):723-729). 19:76. Zehnder, G., G.M. Gurr, S. Kuhne, M.R. Wade, Weinzierl, R., and T. Henn. 1991. Alternatives in S.D. Wratten, E. Wyss. 2007. Arthropod pest insect management: Biological and bio- management in organic crops. Annu. Rev. rational approaches. North Central Regional Entomol. 52: 57-80. Extension Publication 401. Cooperative Zehnder, G. W. and J. Hough-Goldstein. 1990. Extension Service, University of Illinois at Colorado potato beetle (Coleoptera: Urbana-Champaign. –Online: Chrysomelidae) population development www.ag.uiuc.edu/~vista/abstracts/ and effects on yield of potatoes with and aaltinsec.html without straw mulch. J. Econ. Ent. 83(3):1982-1987.

Prepared by H. M. Linker, Integrated Pest Management Coordinator Emeritus D. B. Orr, Professor of Entomology N.C. State University

M. E. Barbercheck, Professor of Entomology Penn State University

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent.

Organic Production Series— Insect Management 36

The Organic Production publication series was developed by the Center for Environmental Farming Systems,

a cooperative effort between North Carolina State University, North Carolina A&T State University, and the North Carolina Department of Agriculture and Consumer Services.

The USDA Southern Region Sustainable Agriculture Research and Education Program and the USDA Initiative for Future Agriculture and Food Systems Program provided funding in support of the Organic Production publication series.

Published by

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

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