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United States Department of Agriculture

Agricultural Research Service

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Location: Stored Product Insect Research Unit

2010 Annual Report

1a.Objectives (from AD-416)
This project proposes to develop better tools to monitor insect populations; to improve IPM strategies for managing insects in stored grain, food processing facilities, and warehouses; to investigate the dispersal patterns that insects utilize to avoid treatments and to reinfest facilities; and to conduct investigations on emerging pests. The primary goal of the research is to reduce losses in quality to grain and grain products caused by insects. To achieve this goal, the following research objectives will be investigated:.
1)improve methods for detecting insects in raw grain and other products by determining the critical factors that affect trap catch, and the relationship between trap catch and actual level of product infestation;.
2)determine how the spatial distribution and population structure of stored-product insects inside and outside processing facilities before, during, and after control treatments affects re-infestation potential;.
3)develop models that predict insect population growth in grain processing facilities and warehouses, and use the models to investigate optimal IPM strategies; and.
4)determine the prevalence and pest potential of psocids and grain mites in stored grain, processing, and warehouse facilities, and conduct ecological studies on those emerging pests that prove to be economically important to implement monitoring and control strategies.

1b.Approach (from AD-416)
Laboratory and field experiments will be conducted to improve insect detection, sampling, and monitoring techniques in raw grain, grain processing facilities, and warehouses. We will improve interpretation of pheromone monitoring programs by determining the important factors that influence trap capture of walking beetles in grain processing facilities and warehouses, and optimize the accuracy of pheromone traps in locating red flour beetle infestation sources. We will characterize the factors responsible for pest resurgence after fumigation or other treatments; determine how spatial distributions of insect pests change before, during, and after control treatments; evaluate how long-term population dynamics of stored-product pests influences pest resurgence following treatment; and assess the potential for pests to survive in food residues and to avoid treated areas during or after control treatments. We will develop computer simulation models for insect pests of grain processing facilities and warehouses, and use these models to optimize monitoring and management strategies. Spatial simulation models will be developed for the red flour beetle, warehouse beetle, and Indianmeal moth. We will investigate the ecology and potential economic impact of emerging pest species, such as psocids and grain mites. Determine the prevalence of these pests in grain storages and mills and develop monitoring and control strategies for species that prove to be economically important.

3.Progress Report
This is the final report for the Project No. 5430-43000-027-00D, which terminated in February 2010. All experiments described in the Project Plan for Project No. 5430-43000-027-00D were completed. A bridging project #5430-43000-031-00D was created until the new 5-year project completes peer review and is implemented in FY 2011.

Substantial progress was made during the 5 years of the project. We field-tested a new commercial electronic grain probe trap and developed statistical models to interpret trap catch. An expert system, Stored Grain Advisor Pro, was modified to automatically obtain data from the grain probe and to estimate the numbers of insects in the grain for three different species of insect pests. Management decisions using the electronic probe were similar to those made using traditional grain-sample estimates. Long-term insect monitoring studies in food processing facilities showed how insect spatial distributions changed after insect control treatments. For insect species that are primarily confined within a structure, such as the red flour beetle, pheromone monitoring provided a good indication of infestation. For species that have a broader spatial scale, such as the Indianmeal moth, pheromone monitoring only provided a measure of infestation pressure; this was because trap capture both outside and inside the structure tended to be similar. We developed a computer model for the red flour beetle in flour mills that can be used to predict the effects of various insect control procedures. A computer model was also developed to simulate population growth of the Indianmeal moth in stored corn. We developed new methods for sampling psocids (an emerging pest) in stored grain. We also investigated the effects of three different types of grain on population growth of four stored-grain psocid pests. Population growth of Liposcelis bostrychophila, L. decolor, L. paeta, and L. entomophila was greatest on sorghum, followed by wheat and rice. Progeny production on eight classes of wheat was highest on durum wheat. The overall impact of the project is that stored product managers now have better tools to monitor insect populations in their facilities, and better methods to make insect-management decisions.

1. Monitoring stored-product insect populations in food processing facilities. Ongoing research by ARS scientists in Manhattan, KS, is providing some of the first information on pest population dynamics in different types of food processing facilities and geographic locations, and also the first in-depth evaluation of treatment efficacy, for both initial reduction and long term population rebound, in commercial food facilities. Comparison of efficacy of the fumigant sulfuryl fluoride to methyl bromide is important because of the impending phase-out of methyl bromide fumigation. Information on aerosol and integrated pest management (IPM) efficacy may reduce the need to perform structural treatments. Results to date indicate considerable variation in efficacy against the target pest species, differences in seasonal patterns in pest activity, and geographic variation in species abundance and diversity. The specific information being generated from this project is currently being used by industry cooperators to help guide their management programs.

2. Evaluation of red flour beetle populations in mills to determine sources of infestation. Red flour beetles are major pests of processed food and food can become infested at different points in distribution channels; from the mill to the retail store. Molecular population genetic tools have the potential to be used to identify where in the distribution channel food products became infested and this can help in targeting pest management. ARS scientists in Manhattan, KS, with university collaborators investigated the genetic diversity and differentiation among nine populations collected from wheat and rice mills throughout the USA. Results indicated that there was limited differentiation among the populations and correct assignment to source population was possible in only 56% of individuals. These results indicate either a high level of movement of individuals across large geographic distances, most likely by human movement of infested material, or that better molecular markers are needed to resolve these different source populations.

3. Red flour beetle ability to move among floors in flour mill. Understanding the dispersal ability of an insect pest in a food facility is important in terms of interpretation of monitoring programs, understanding the rate at which an infestation can spread, and determining population structure. Red flour beetles typically disperse by walking or in short flights, so they may have limited ability to move among floors in multistory structures. Using self-mark and recapture methods, ARS scientists in Manhattan, KS, showed that beetles were able to move among floors, typically downward, even in a mill that is relatively tightly sealed between floors. Heat treatments applied for insect control drive insects from hidden refugia, but did not increase movement among floors. These results suggest that red flour beetles may be more mobile within flour mills then was originally suspected, which will be useful in determining sources of insects captured in traps and in modeling population dynamics.

4. Pattern of flour dust accumulation on surfaces can increase red flour beetle response to pheromone traps. Pitfall traps baited with pheromone and food attractants are commonly used to monitor walking red flour beetles in flour mills, but in operating flour mills flour dust tends to accumulation on surfaces and this may influence beetle walking patterns and likelihood of encountering traps. An ARS scientist in Manhattan, KS, demonstrated that the pattern of flour dust accumulation impacted beetle behavior and response to traps, with certain flour dust accumulation patterns actually increasing probability of capture in traps. Understanding how red flour beetle captures are impacted by the environment in which the trap is placed will help improve the interpretation of monitoring programs for the food industry.

5. Simulation model for the red flour beetle in flour mills. Insect contamination of flour has many negative impacts on the industry including damage to brand identity, failure to pass inspections, and the cost of product returns. The red flour beetle is the major insect pest of flour mills in the U.S. With the phase-out of methyl bromide for fumigation, the milling industry needs alternative treatment strategies. ARS scientists in Manhattan, KS, developed a computer model for the red flour beetle in flour mills that can be used to predict the effects of various insect control procedures. The model was used to investigate several fumigation strategies. Insect population rebound following fumigation was much longer in mills that were fumigated in the fall compared to spring fumigations. Simulated fumigations with sulfuryl fluoride resulted in faster population rebound compared to methyl bromide because of reduced egg mortality in the former. Findings from this study will be used to develop optimal treatment programs for flour mills using alternative methods such as heat and sulfuryl fluoride.

6. Indianmeal moth simulation model developed. The Indianmeal moth is a common pest of stored corn. ARS scientists in Manhattan, KS, and Gainesville, FL, developed a computer model to simulate population development of the Indianmeal moth in stored corn. The model accurately simulated population development of Indianmeal moths in corn stored during fall and winter of three separate storage seasons in South Carolina. The model predicted that populations would increase after winter as grain temperatures rose, but observed populations in the grain bins never increased after winter. Despite this, the model should be useful from a management perspective because the corn is being sold off or used up after winter, and the observed Indianmeal moth populations never reached damaging levels after winter. The model will be useful for predicting Indianmeal moth population levels in stored corn to time management actions.

7. An agent-based model of the red flour beetle developed. The red flour beetle is a common insect pest infesting flour mills. Over the last 80 years, dozens of mathematical models have been developed to simulate its population dynamics. However, while these models predict general population trends, they are not able to simulate individual behavior and movement, and most don’t include a spatial dimension. ARS scientists in Manhattan, KS, built an agent-based model to explicitly represent individual beetles, fragmented landscapes, and the interactions between beetles as well as the interactions between beetles and their environment. This model can be easily adjusted to different flour landscapes and different scales. The population dynamics, age structure, spatial distribution and movement behaviors are simulated in this agent-based model. We collected five years of laboratory data that were used to validate the model. The model demonstrated that population stability is sensitive to landscape fragmentation. This information is useful to develop sanitation strategies in flour mills to suppress beetle population growth.

8. Effect of commodity characteristics on population growth of four stored-grain psocid pests. Psocids, or booklice, are emerging pests of stored grains, and little is known about them. ARS scientits in Manhattan, KS, determined that population growth of four psocid species, Liposcelis bostrychophila, L. decolor, L. paeta, and L. entomophila was greatest on sorghum, followed by wheat and rice. Progeny production on wheat containing varying amounts of cracked kernels did not increase as cracked kernel content increased; instead, progeny production peaked at 20% for L. bostrychophila adults and nymphs, at 10% for L. decolor, and at 50% for L. paeta adults. No further increases were noted beyond these levels of cracked wheat content. Progeny production on eight classes of wheat was highest on durum wheat. The results indicate that there are considerable variations in psocid population growth among the different commodities tested, and this information may be used to predict the degree to which stored commodities are susceptible to psocid infestation.

Review Publications
Nansen, C., Flinn, P.W., Hagstrum, D.W., Toews, M.D., Meikle, W.G. 2009. Interspecific Associations Among Stored-Grain Beetles. Journal of Stored Products Research. 45: 254-260.

Athanasiou, C.G., Arthur, F.H., Throne, J.E. 2009. Efficacy of Spinosad in Layer-Treated Wheat Against Five Stored-Product Insect Species. Journal of Stored Products Research 45: 236-240.

Athanassiou, C.G., Arthur, F.H., Throne, J.E. 2010. Effects of Short Exposures to Spinosad-Treated Wheat or Maize on Four Stored-Grain Insects. Journal of Economic Entomology. 103: 197-202.

Cheng, L., Nechols, J.R., Margolies, D.C., Campbell, J.F., Yang, P. 2010. Assessment of Prey Preference by the Generalist Predator, Mallada basalis (Walker), When Offered Two Species of Spider Mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor) on Papaya. Biological Control. 53: 267-272.

Flinn, P.W., Hagstrum, D.W., Reed, C., Phillips, T.W. 2010. Insect Population Dynamics in Commercial Grain Elevators. Journal of Stored Products Research. 46(1): 43-47. doi:

Guedes, N.P., Guedes, R.C., Campbell, J.F., Throne, J.E. 2010. Contest-Behavior of Maize Weevil Larvae when Competing within Seeds. Journal of Animal Behavior. 79: 281-289. doi:10.1016/j.anbehav.2009.10.022.

Athanassiou, C.G., Opit, G.P., Throne, J.E. 2010. Influence of Commodity Type, Percentage of Cracked Kernels, and Wheat Class on Population Growth of Stored-Product Psocids (Psocoptera: Liposcelidae). Journal of Economic Entomology. 103: 985-990. DOI: 10.1603/EC09280.

Opit, G.P., Throne, J.E., Payton, M.E. 2010. Reproductive Parameters of the Parthenogenetic Psocid Lepinotus reticulatus (Psocoptera: Trogiidae) at Constant Temperatures. Environmental Entomology. 39: 1004-1011. DOI: 10.1603/EN10011.

Phillips, T.W., Throne, J.E. 2010. Biorational Approaches to Managing Stored-Product Insects. Annual Review Of Entomology. 55: 375-397.

Romero, S.A., Campbell, J.F., Nechols, J.R., With, K.A. 2010. Movement Behavior of Red Flour Beetle: Response to Habitat Cues and Patch Boundaries. Environmental Entomology. 39: 919-929. DOI: 10.1603/EN09324.

Hagstrum, D.W., Flinn, P.W., Reed, C.R., Phillips, T.W. 2010. Ecology and IPM of Insects at Grain Elevators. Biopesticides International. 6: 1-20.

Last Modified: 4/17/2014
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