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Biological Pest Control

Biological Pest Control

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Biological Control

ntegrated pest management (IPM) involves the use of a combination of strategies to reduce pest populations Steps for conserving beneficial Isafely and economically. guide describes various • Recognize beneficial insects. agents of biological . These strategies include judicious use of and cultural practices, such as • Minimize applications. rotation, tillage, timing of planting or harvesting, • Use selective (microbial) , or treat selectively. planting trap crops, sanitation, and use of natural enemies. • Maintain ground covers and crop residues. • Provide and sources or artificial . Natural vs. biological control Natural pest control results from living and nonliving Predators and parasites factors and has no involvement. For example, weather and are nonliving factors that can contribute Predator insects actively hunt and feed on other insects, to natural control of an pest. Living factors could often preying on numerous . Parasitic insects lay include a or that naturally controls a pest. their on or in the of certain other insects, and does involve human action and the young feed on and often destroy their hosts. Not all is often achieved through the use of beneficial insects that predacious or parasitic insects are beneficial; some kill the are natural enemies of the pest. Biological control is not the natural enemies of pests instead of the pests themselves, so natural control of pests by their natural enemies; host be sure to properly identify an insect as beneficial before resistance; or the judicious use of pesticides. you work to increase its population. Populations of beneficial insects can be increased by conservation, augmentation or importation. The three P’s of biological control Conservation of a pest’s natural enemies often requires a Biological control agents consist of the three P’s: change in production practices or applications so • Predators as not to harm the beneficial species. • Parasites Augmentation involves adding natural enemies to the • area, usually by buying or rearing them. This strategy works Each of these control agents is a natural enemy that can only if the practice adds to overall death of the target pest be used to reduce, delay or prevent pest . instead of replacing existing causes of death. Natural enemies can be introduced after the pest is Importation is the classical biological control strategy. established. For example, the Vedalia was introduced Many pests are exotics — that is, they have been brought to the as a natural predator of cottony into a region that they are not native to, usually accidentally. cushion scale. When eradication of a pest is impossible or The natural enemies of these pests can be imported so as not economically feasible, such as with the gypsy , to “reunite” the pests with their natural control agents. predators or pathogens can be used to delay or slow the Importation must involve extensive natural hosting studies spread of the pest. Prevention of a predictable pest through and a stage to ensure that bringing these natural the release of natural enemies early in the season is rarely enemies into the area won’t cause further problems. attempted because of the time it takes for populations of the beneficial insects to increase sufficiently. To effectively use biological control, you need to know Pathogens what pest you are trying to control and what its natural Certain , , fungi, protozoa and enemies are. Some resources that can help you identify are beneficial pathogens. Many of these pathogens are a pests and their natural enemies are listed in the For more form of natural control in that they can drastically reduce a information and Also from MU Extension Publications sections. pest’s population in ; for example: • Viruses in budworm, corn earworm, Written by looper, tent and Moneen M. Jones, Research Entomologist, Division of Plant Sciences, • Fungi in alfalfa , and green College of Agriculture, and Natural Resources cloverworm extension.missouri.edu > agriculture > pests and > integrated pest management > ipm1034 • in , corn borer and many Importation successes others Although some pathogens have been mass-produced and The classic example of successful control of a pest through packaged, for the most part these have not been readily importation of its natural enemy is the Vedalia beetle for formulated as effective microbial insecticides. control of cottony cushion scale in citrus. Between 1868 and 1870, cottony cushion scale was introduced from Viruses and became a serious pest of citrus and ornamentals. In Viruses commonly cause outbreaks and popula- 1887, C.V. Riley convinced the Fruit Growers’ tion crashes in caterpillars. A few -based Convention to pressure the U.S. Congress to provide $2,000 are available commercially, but they are not used widely in for the covert collection of natural enemies in Australia. Albert the U.S. These products include viruses that infect codling Koebele sailed for Australia in August 1888, presumably to , gypsy moths, corn earworms, tussock moths and represent the California citrus growers at the world agricultural others. exposition. Koebele brought back several thousand parasites (Cryptochaetum iceryae) and a few hundred Vedalia Bacteria (Rodolia cardinalis). The Vedalia beetles were held on trees thuringiensis (Bt) toxins work by developing under mesh tents to increase their numbers; then they were crystal in the gut of insects that cease their feeding transferred from to orchard on branches by growers. and quickly cause death. Species are available that kill pest To date, the beetle is the best control measure for cottony larvae: cushion scale. • B. israelensis and B. for larvae of several Other successful examples include parasites of the alfalfa mosquitoes, black and fungus gnats weevil, beetles for gypsy moth suppression, larval parasites of • B. popilliae and B. lentimorbus for larvae cereal beetle, and the mealy bug destroyer beetle. Insect-pathogenic fungi Insect-pathogenic fungi often cause disease outbreaks in been commercialized as a is locustae, a insect populations, but few have been commercialized as species that attacks grasshoppers. biopesticides. One reason for the lack of commercialization is that production of virulent strains that maintain viability Insect-parasitic nematodes “on the shelf” is difficult. Another is that the effectiveness of The nematodes that have been cultured for sale as products applied in the field is affected by the weather and biopesticides include species in the genera Steinernema the field’s microhabitat. and Heterorhabditis. They enter an insect’s body through The following fungi are examples of those that kill the , or spiracles and move into the body insects: cavity, where they release symbiotic bacteria ( • anisopliae infects a broad range of hosts, or species) that multiply within the host including corn rootworms, white grubs and root insect. by these bacteria is what kills the insect . A commercial bait station uses M. host. The nematodes feed on the bacteria, complete anisopliae to kill . their development, and reproduce, yielding thousands of • (white fungus) kills the progeny that then seek another host. and . Nematodes can be effective against insects, • muscae (and E. grylli and others) kills particularly in settings where can be used flies, seed and root adults, and other insects. to maintain soil moisture. Targets have included root The fungus sporulates from dead or swollen adult flies. weevil larvae, seed and root , fungus gnat larvae and several other pests. Nematodes have not proven to Microsporidia be effective against wireworms, corn rootworms, A microsporidian is a parasitic fungus. An important or several other key pests. Midwestern example is Nosema , a pathogen of the European corn borer. Although microsporidia can kill their hosts outright, often do not cause death For more information rapidly. Infected individuals develop more slowly and are Biological Control: A Guide to Natural Enemies in North smaller, and infected females lay fewer eggs, many of which America, Cornell University: http://www.biocontrol. will become infected and die. N. pyrausta causes periodic .cornell.edu collapses in European corn borer populations in Missouri Integrated pest management publications, University of and neighboring states. The only microsporidian that has Missouri Extension: http://extension.missouri.edu/ipm

■ Issued in furtherance of the Cooperative Extension Work Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. Director, Cooperative Extension, University of Missouri, Columbia, MO 65211 ■ an equal opportunity/ADA institution ■ 573-882-7216 ■ extension.missouri.edu ipm1034 page 2 New 8/15/Web

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