Guide to the Biological Control of Some Common Yard and Garden Pest Insects in New Mexico COLLEGE OF AGRICULTURE AND HOME ECONOMICS BRINGING SCIENCE TO YOUR Cooperative Extension Service • Circular 607 LIFE Guide to the Biological Control of Some Common Yard and Garden Pest Insects in New Mexico Joe Ellington, Tracey Carrillo, John White, Carol Sutherland, David Richman, Jeff Drake and Scott Bundy 1 Introduction learn to recognize those species that are Sometimes insects, mites or their relatives landscape pests and, perhaps, even some limit enjoyment of our landscape and garden species that are considered beneficial. Some of plants. We are familiar with pests that infest the less common and smaller pest species and fruit, vegetables, flowers and foliage or make their natural enemies may offer special plants wither, change colors, develop spots or challenges for identification and management. streaks or even die. But just as pests damage But further study, experience and observation some plants, those same pests probably have can help in manipulating them. one or more natural enemies that limit their In IPM, a variety of pest control numbers and their damage. measures are used to reduce pest “Biological control” of pests involves populations below damaging levels. Many either natural or human-assisted control of tools are available, but some will be more certain pest species by predators, parasites valuable, manageable, available or (parasitoids, as defined below) or pathogens. affordable than others. Some tools for This circular outlines important definitions, home gardeners include: concepts and examples of biological control • Sanitation-cleaning: Remove or of some common yard and garden pests in destroy debris if it is infested, or New Mexico. Home gardeners should note harbors pests. Sometimes leaving that biological control is complex, and they infested debris is an option, if it should assess the pros and cons of adopting harbors beneficial insects. these techniques as part of an overall • Physical-mechanical control: Hot or Integrated Pest Management (IPM) strategy cold treatments, crushing, burying, for their properties. screening or covering affected plants Not all insects and their relatives are to prevent infestation. harmful to landscapes. Relatively few species • Cultural control: Rotate crops, till cause most of the damage to plants. The soil, try irrigation strategies, trap diversity of plants in most home landscapes crops, or adjust planting and tends to limit the damage done by any harvesting dates. particular pest. Through observation, reading • Genetic control: Use plant varieties and short courses on the subject, gardeners can bred for resistance to certain pests. 1Professor, Department of Entomology, Plant Pathology, and Weed Science (EPPWS); Senior research specialist, EPPWS; Doña Ana County Extension Agent- Agronomy and Horticulture/4-H; Extension Entomologist/State Entomologist, Department of Extension Plant Sciences; Science Specialist, EPPWS; Research Scientist, USDA/APHIS; and Assistant Professor, EPPWS. Cooperative Extension Service • Circular 607 1 • Chemical control: Use noninvasive ideas that may enhance biological control: inorganic or organic chemicals to kill • Reduce or eliminate insecticides, or manage pests. especially those that are nonselective or • Biological control: Conserve natural have long residuals. enemies already present in the area, • If insecticides are used, apply them in introduce new species or augment noninvasive ways. existing populations of natural enemies – Apply when beneficial insects are (parasitoids, predators or pathogens) to not present. decrease populations of particular pests – Apply reduced rates and only when below damaging levels. warranted (not calendar sprays or “preventative treatments”). – Apply to alternate rows or alternate Management Practices that plants or only to affected plants. Enhance Biological Control – Apply systemic or host-specific Biological control is a broad concept that insecticides. can be used to manage pests on many – Apply to specific restricted areas of kinds of plants, including annual bedding plants, such as trunks or roots. plants, vegetables, and perennial flowers, • Provide sources of nectar, pollen and shrubs, vines and trees. In practice, alternate hosts for beneficial insects biological control of particular pests may during the growing season. be implemented by conserving the various • Provide overwintering sites for species of natural enemies already present beneficial insects. in the area. Where no effective natural • In general, don’t kill all of the harmful enemy is present, entomologists or various insects in an ecosystem. Reducing the government agencies may introduce one or density of harmful species, in host- more new species to the area. Candidates for specific ways, often is acceptable. This release are screened carefully before permits practice allows the beneficial complex are issued for release to ensure that the to continue building for future control. introduced species don’t become pests The longer you can refrain from themselves. These introduced species may applying an insecticide, the more likely be released into infested areas immediately biological control will work. after screening, or they may be lab reared through several generations to increase their Selected chemicals have a place in numbers before release. In some cases, certain yard and garden IPM programs, entomologists may recommend because they are considered less toxic to augmentation as another means of beneficial insects and mites due to the ways enhancing biological control of a pest. In they are applied or their modes of action. these situations, the natural enemy species is Broadly labeled insecticides, which are already present, but its numbers are too low persistent and generally toxic to a wide to reduce a pest population below damaging variety of insects, can be harsh to garden levels. In response, entomologists may rear ecosystems, resulting in environmental that natural enemy species through several contamination, possible increased generations so that, after release, its numbers insecticide resistance in target pests, are higher and the species has a better chance decreased beneficial insects, a resurgence of controlling the pest. Here are additional of target pests, increased prominence of 2 Cooperative Extension Service • Circular 607 secondary pests and their damage, and directions on these products. potential damage (phytotoxicity) to plants Bacillus thuringiensis (Bt) toxins can be that required protection in the first place. specific to particular insect groups. This Some products, such as pheromones, naturally occurring bacterium has been long are host specific, impacting just one or known to kill certain kinds of insects. The a few species. Many pheromones are sex bacterial infection of certain caterpillars, for attractants, analogous to a perfume that aids example, turns lethal when the bacteria one sex in locating the other as well as release toxins into the insect gut, paralyzing releasing additional courtship behavior. In and killing it. Bt can be grown in cultures commercial catalogs, pheromone products and commercially produced for homeowner are named according to the species they use in specific applications. There are several attract. These blends of organic chemicals subspecies of this bacterium, each affecting usually attract only one sex. For most moths, different kinds of insects. Subspecies males are attracted to chemical baits that kurstaki, the longest recognized and resemble pheromones produced and released commercially produced Bt product, affects naturally by females of the species when they caterpillars or “worms” of certain butterfly are ready to mate. Because some similar and moth species. Subspecies israelensis insect species may be attracted to sticky traps affects certain aquatic fly larvae, especially because of their color, placement or mosquitoes and black flies. A third pheromone mixture, make sure the insects subspecies, sandiego or tenebrionis, kills on the traps are the target pests, rather than certain beetle larvae or grubs, such as those harmless look-alikes. While trapping might of elm leaf beetles. For such products, seem ideal for eliminating insecticides, it is homeowners need to read the labels carefully more the exception than the rule. However, not only for application methods but also for it indicates how detailed studies of pest limitations. Properly identifying pests biology and behavior can be useful in susceptible to these treatments is a must. developing pest control protocols. Synthetic Elemental sulfur can be used to control sex pheromones for adult moth attraction spider mites in some situations. Sulfur also can be used in sticky traps to monitor flights can cause phytotoxicity in cantaloupes and and predict egg laying or hatching times. cucumbers. However, sulfur does not seem If a pesticide must be used to control to have direct negative effects on nontarget certain pests, plotting the pest captures organisms. in pheromone traps can be helpful to Insect growth regulators (IGRs) are properly target treatments. More recently, compounds that alter insect growth patterns entomologists have found that “over dosing” in various ways that result in metabolic some commercial crops with certain errors and asynchronous development. They pheromones confuses at least a few pest are species- or group-specific and have a low species to the point that males can not find toxicity