Overview of North American stored product research

Major locations for stored product research in North America are in Winnipeg, Manitoba, Canada, and Manhattan, Kansas, USA. Recent personnel changes and research areas are reviewed. One of the pressing research areas in the U.S. is reducing the need for fumigations in flour mills and evaluating alternative treatments. Long-term studies are beginning to show efficacy of better IPM practices, including use of aerosol treatments, for reducing the need for fumigation. Heat treatment as an alternative to fumigation continues to be refined through research. Models have been developed for optimizing heat treatments and fumigations. Studies at grain elevators are optimizing insect management at these large storage facilities, including better sampling methods and computer programs that aid in decision making. Recent studies are beginning to look at insect populations in feed mills and their association with microbes. A number of studies have investigated the biology and control of psocids, which are emerging pests of stored products in the U.S. There have been major research efforts in both Canada and the U.S. to develop better sampling and detection methods, including thermal imaging, automated digital x-rays, molecular methods, and development of better attractants and improved interpretation of trap catches. The red flour beetle, Tribolium castaneum, is the first agricultural pest to have its genome sequenced, and mining the genome has produced vast knowledge of various physiological processes that might be exploited for control of this and other pests. Expected future research trends are on aerosol treatments of structural facilities, improved methods for detecting internal insect pests, psocid biology, improved attractants, improved interpretation of trap catches for making pest management decisions, and application of genomic technologies for insect control. 1. Locations for stored product research The main center for stored product research in Canada is in Winnipeg, Manitoba. Entomologists Paul Fields and Noel White are at the Agriculture and Agri-Food Canada Cereal Research Centre, and biosystems engineers Digvir Jayas and Jitendra Paliwal are at the University of Manitoba. Most of the storage research is at the Canadian Wheat Board Centre for Grain Storage Research on the University of Manitoba campus. The main center for stored product research in the United States is in Manhattan, Kansas. The Stored Product Insect Research Unit (previously the Biological Research Unit) at the Center for Grain and Animal Health Research (previously the Grain Marketing and Production Research Center), which is part of the United States Department of Agriculture’s Agricultural Research Service (USDA-ARS), has seven scientists working on basic and applied aspects of stored-product entomology. These are Frank Arthur, Dick Beeman, Jim Campbell, Paul Flinn, Jeff Lord, Brenda Oppert, and Jim Throne. During the past four years, Tom Phillips moved from Oklahoma State University, where he had faculty responsibility for stored-product entomology, to be Head of the Department of Entomology at Kansas State University, which has a long history of training students in stored-product entomology; George Opit moved from a postdoctoral position at the USDA-ARS Stored Product Insect Research Unit to take Tom Phillips’ position at Oklahoma State University; and Dirk Maier moved from Purdue University to be Head of the Department of Grain Science and Industry at Kansas State University. Bhadriraju Subramanyan continues his work on stored-product entomology in the Department of Grain Science and Industry at Kansas State University. Other North American university faculty with major assignments in stored products are Linda Mason at the Purdue University Department of Entomology, Charles Woloshuk at the Purdue University Department of Botany and Plant Pathology, and Carol Jones at the Oklahoma State University Department of Biosystems Engineering. A number of other state, federal, and university researchers in North America have partial appointments in stored products. 10 International Working Conference on Stored Product Protection Julius-Kühn-Archiv, 425, 2010 43 2. Research highlights and trends in North America during the last four years 2.1. Reduced use of methyl bromide for structural fumigations Use of methyl bromide for structural fumigations has decreased steadily in North America since its phase-out was proposed. Most facilities have reduced fumigations from three calendar-based fumigations per year to one or fewer per year. This has been achieved through better pest management practices, such as improved monitoring and sanitation, and through use of aerosols or spot treatments with heat or insecticides. Heat is also used for insect control in some facilities, instead of fumigation. Sulfuryl fluoride is also being used for fumigation of some facilities, rather than using methyl bromide. Efforts have been made to model structural fumigations to try to improve efficacy. Chayaprasert et al. (2008, 2009) developed a model for structural fumigations, and they used it to investigate fumigation leakage rates from flour mills under different weather conditions. They showed that leakage rates varied within the same facility at different times of the year, indicating that leakage rate should be calculated from sealing factors for the particular facility and using historical local weather conditions for the actual fumigation period. Their results showed that leakage rates for methyl bromide and sulfuryl fluoride did not differ when simulations were run under the same weather conditions for a facility, when the fumigants were applied at the same dosages. Cryer (2008) also found that predicted leakage rates for the two fumigants were similar. Although aerosol insecticide applications are being used more frequently in flour mills and other structures, there are few recent reports on their efficacy. Toews et al. (2006b) monitored insect populations in an operating flour mill during a 22-month period. They found that insects were almost always captured inside the mill in the first trapping period after fumigation or aerosol application with dichlorvos+pyrethrin, but it wasn’t clear if the insects survived treatment or immigrated from outside. Arthur and Campbell (2008) showed that survival of the confused flour beetle, Tribolium confusum (Jacquelin du Val) (Coleoptera: Tenebrionidae), increased when food was provided after treatment with a pyrethrin-CO2 aerosol, emphasizing the importance of sanitation in facility pest management programs. This aerosol treatment seemed to have no long-term effect on resident insect populations in the study warehouse. Arthur (2008) investigated efficacy of synergized pyrethrin and methoprene aerosols for control of the red flour beetle, Tribolium castaneum (Herbst), and T. confusum in a commercial food storage facility, and in this study found no effect of presence of food on efficacy of the synergized pyrethrin aerosol. Tribolium confusum adults were less susceptible to the synergized pyrethrin aerosol than T. castaneum adults. Few treated larvae or pupae of either species survived to the adult stage. Few larvae of either species exposed to the insect growth regulator methoprene survived to become adults, and only 13% of Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), larvae embedded in food media and exposed to methoprene survived to the adult stage. Overall, results of aerosol studies show good efficacy of aerosols and good promise for the use of aerosols to reduce the need for structural fumigations. Much research has been conducted on efficacy of heat for controlling insects in structures, but recent efforts have begun to synthesize these data to provide tools to users for optimizing heat treatments. Boina et al. (2008) developed a model for predicting survival of T. confusum during heat treatments. The model was validated with independent data from nine heat treatments in structures, and the model predicted the observed mortality well. 2.2. Insect management at grain elevators Efforts continue to improve insect management at large, central grain storages. Arthur et al. (2006) sampled grain residues at nine elevators over a two-year period and found that 80% of the insects in grain residues were in the genera Sitophilus and Cryptolestes. Numbers of Cryptolestes in samples increased rapidly in spring, and then remained fairly constant. Numbers of Sitophilus in samples increased through warm months, and then decreased. Pest insects were present in 42% of samples, while beneficial insects were found in 5% of samples. The parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) comprised 90% of beneficial insects found. Pest insects were most prevalent in samples taken from elevator boot pits and tunnels. The large numbers of insects in these samples indicate the need for good sanitation around grain storages. 10 International Working Conference on Stored Product Protection 44 Julius-Kühn-Archiv, 425, 2010 Flinn et al. (2007) extended their previous expert system to aid in pest management decision making for farm-stored grain to be applicable to elevator storages. Users can input current grain temperatures and moistures and numbers of insects from grain samples, and the expert system uses built-in models to make predictions about future insect populations and to recommend management actions. The validity of the expert system was tested in a four-year project at commercial grain elevators. The program failed to identify unsafe storage conditions in only 2 of 399 bins in Kansas, and it correctly identified unsafe storage conditions in all 114 bins in Oklahoma. The number of bins fumigated was reduced because only bins with higher densities of insects were fumigated, rather than treating all bins on a calendar basis. The expert system is being used by a scouting company that was de