Biorational Approaches to Managing Stored-Product Insects
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ANRV397-EN55-20 ARI 2 November 2009 12:21 Biorational Approaches to Managing Stored-Product Insects Thomas W. Phillips1 and James E. Throne2 1Department of Entomology, Kansas State University, Manhattan, Kansas 66502; email: [email protected] 2USDA-ARS Grain Marketing and Production Research Center, Manhattan, Kansas 66502; email: [email protected] Annu. Rev. Entomol. 2010. 55:375–97 Key Words First published online as a Review in Advance on biological control, insect growth regulators, pheromones, physical September 8, 2009 control, sampling, decision-making The Annual Review of Entomology is online at ento.annualreviews.org Abstract by Kansas State University on 12/15/09. For personal use only. This article’s doi: Stored-product insects can cause postharvest losses, estimated from up 10.1146/annurev.ento.54.110807.090451 to 9% in developed countries to 20% or more in developing coun- Copyright c 2010 by Annual Reviews. tries. There is much interest in alternatives to conventional insecticides Annu. Rev. Entomol. 2010.55:375-397. Downloaded from arjournals.annualreviews.org All rights reserved for controlling stored-product insects because of insecticide loss due to 0066-4170/10/0107-0375$20.00 regulatory action and insect resistance, and because of increasing con- sumer demand for product that is free of insects and insecticide residues. Sanitation is perhaps the first line of defense for grain stored at farms or elevators and for food-processing and warehouse facilities. Some of the most promising biorational management tools for farm-stored grain are temperature management and use of natural enemies. New tools for computer-assisted decision-making and insect sampling at grain eleva- tors appear most promising. Processing facilities and warehouses usually rely on trap captures for decision-making, a process that needs further research to optimize. 375 ANRV397-EN55-20 ARI 2 November 2009 12:21 INTRODUCTION topics are available (38, 92). New research and primary literature on stored-product insects Stored-product insects are serious pests of continue to be generated at a steady pace by re- Pheromones: dried, stored, durable agricultural commodi- searchers at universities, but more so by scien- chemical signals used ties, and of many value-added food products tists at government-sponsored research centers between members of and nonfood derivatives of agricultural prod- the same species, some in North America, Europe, Asia, and Australia ucts worldwide. Stored-product insects can of which are used in (82). cause serious postharvest losses, estimated from synthetic form for pest The motivation and influence behind cur- management up to 9% in developed countries to 20% or rent research on stored-product IPM are those more in developing countries (88), but they IPM: integrated pest that have led the field since the beginning, and management also contribute to contamination of food prod- more immediate objectives have been given im- ucts through the presence of live insects, insect petus by government regulations, consumer de- products such as chemical excretions or silk, mands, and broader commercial needs. The tra- dead insects and insect body fragments, general ditional objectives are to store grain and food in infestation of buildings and other storage struc- a wholesome way with minimum impact from tures, and accumulation of chemical insecticide insects or from chemical insecticides that may residues in food, as well as human exposure to be used in pest control. More recently, the dangerous chemicals as a result of pest control worldwide phaseout and ban of the fumigant efforts against them. There are many safe, effec- insecticide methyl bromide, an effective com- tive, and relatively simple prevention and con- pound for killing postharvest insects, under the trol methods available to manage populations international agreement of the Montreal Proto- of stored-product insect pests without the use col has motivated research into various alterna- of chemical insecticides. In this review we de- tives to replace methyl bromide (31). The U.S. scribe and give updated information on biora- Food Quality Protection Act of 1996 focused on tional approaches to managing stored-product evaluating all registered pesticides, with partic- insect pests. These approaches either (a) di- ular attention to worker and consumer expo- rectly use biologically based materials, such as sures to chemical residues; thus, reduction or biologically derived insecticides or biological elimination of residues in grain and foods was control organisms, to control pests or (b) take targeted by research for nonchemical alterna- advantage of key aspects of the pest’s biology to tives (82). In addition to regulatory pressures eliminate or manage pest populations through for low-risk control of stored-product insects, manipulation of the physical and biological en- consumers and governments around the world vironments of the target species. by Kansas State University on 12/15/09. For personal use only. set standards for organic food, which should Stored-product insects have been associ- be derived from raw products that are free of ated with human activities since the earliest human-made chemicals, among other require- civilizations, and methods for their diagno- ments (120). Thus, research on chemical-free Annu. Rev. Entomol. 2010.55:375-397. Downloaded from arjournals.annualreviews.org sis and control have been reported for over or biologically based methods to control stored- a century (60). Indeed, the first issue of the product insects was encouraged and supported. Annual Review of Entomology included an arti- This current review briefly covers the basic lit- cle on stored-product insects (79). Since then erature on our topic and is an update on more significant reviews have covered pheromones of recent literature, focusing on biologically based stored-product insects (15) and alternatives to approaches that have proven efficacy, are legally methyl bromide for controlling storage pests registered for use or are in the registration pro- (31). Recent edited books have covered ecol- cess, and have the greatest chance of commer- ogy and integrated pest management (IPM) of cial adoption by the grain, food, and pest con- stored-product insects (41, 103) and alterna- trol industries. Our review focuses on cereal tives to pesticides for controlling storage pests grains and their products, rather than oilseeds (104), and comprehensive textbooks on related and edible legumes, although the material is 376 Phillips · Throne ANRV397-EN55-20 ARI 2 November 2009 12:21 relevant to all durable stored agricultural prod- by pests whose larvae either feed and develop ucts, of both plant and animal origin, that may inside the kernel or develop outside intact be threatened by stored-product insects. Mites kernels. The internal-feeding insects have Aeration: the practice (Acarina) are not covered in depth, although been referred to historically as primary pests, of drawing outside air biorational management tactics for insect pests while those feeding outside the kernels on into a grain storage bin are generally relevant to mites. Vertebratepests, broken and fine material have been referred to or other structure for although of substantial economic and public as secondary pests. Some of the most serious the purpose of health considerations, are reviewed elsewhere economic insect pests of wheat are internal changing the temperature or (41). feeders such as the lesser grain borer, Rhyzop- moisture content of ertha dominica (F.) (Coleoptera: Bostrichidae), the stored grain which lays eggs outside the kernel and the External-feeding HABITATS AND GUILDS OF larvae bore into the kernel to complete de- pests: insects whose STORED-PRODUCT INSECTS velopment to the adult stage, and the rice larvae develop outside weevil, Sitophilus oryzae (L.) (Coleoptera: sound grain kernels, Bulk Commodities are generally unable to Curculionidae), which lays eggs directly inside damage sound kernels, The stored-grain environment is unique among the kernel. External-feeding pests of wheat and predominantly most agroecosystems in that it is entirely are the red flour beetle, Tribolium castaneum require broken human-made and not subject to rapid and ex- (Herbst) (Coleoptera: Tenebrionidae); the kernels, grain dust or treme changes in environmental conditions. rusty grain beetle, Cryptolestes ferrugineus milled grain products After harvest, grain is placed into storage in a (Stephens) (Coleoptera: Laemophloeidae); for food structure such as a steel bin, concrete silo, a flat and the sawtoothed grain beetle, Oryzaephilus Internal-feeding pests: insects whose storage such as a steel building, or simply on a surinamensis (L.) (Coleoptera: Silvanidae). larvae develop inside concrete slab with the grain covered with plas- Insects most commonly found in shelled corn seeds and kernels of tic. Steel bins may vary in size, with volumes (maize) are internal feeders such as the maize grain and generally that hold 30 to 8000 tons of grain. A concrete weevil, Sitophilus zeamais Motschulsky, and cause damage to silo at a grain elevator typically may contain 500 the Angoumois grain moth, Sitotroga cerealella otherwise sound to 800 tons of grain, and a flat storage, in which (Olivier) (Lepidoptera: Gelechiidae); external- kernels of grain grain is dumped into a large pile in a protected feeding pests include C. ferrugineus; the flat Stored products: dried, durable building, may contain as much as 80,000 tons of grain beetle, C. pusillus