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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGY, SAMPLING, AND MODELING OF INSECT PESTS OF STORED GRAIN, PROCESSING FACILITIES, AND WAREHOUSES
2009 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
Monitoring programs at food processing facilities around the US are being used to evaluate seasonal patterns in stored-product insect populations and the impact of structural treatments and other management tactics on pest populations. Red flour beetle movement patterns were evaluated in both laboratory studies and in a pilot scale flour mill. Ability of the red flour beetle to disperse among floors in a flour mill was studied. Molecular genetic techniques were used to determine relationships among populations of red flour beetle collected in different flour mills. Populations in different mills differed from each other and appeared stable over time at one mill location. Spatial distribution of stored-product insects in the landscape around food facilities was investigated. Insect distribution was not correlated with the distribution of product spillage, so other factors may be more important. A model for the red flour beetle in flour mills was developed. Data from the insect monitoring studies is being used to validate the model. The model will be an important tool to evaluate different pest management strategies for the red flour beetle, which is the primary insect pest of flour mills. Investigated ecology and control of psocids, which are emerging pests of stored products about which little was known. Showed that of insecticides registered for stored wheat, rice, and corn in the U.S., organophosphate insecticides were most efficacious for psocid control. Showed that a new biological insecticide, Spinosad, did not control the major psocid pests Liposcelis paeta and L. bostrychophila, but did control the less common psocid pest Lepinotus reticulatus. Developed a method for conducting attractant bioassays for psocids, which will be used to develop better traps.


4.Accomplishments
1. Stored-product insect pest population dynamics in food processing facilities. Ongoing research 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 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. Distribution of flour spills impact how red flour beetles move and distribute eggs. Commercial food processing facilities are large complex landscapes of favorable habitat patches within a matrix of unfavorable areas, and this pattern impacts the abundance and distribution of pest species. Red flour beetle is a major insect pest of flour mills and serves as a useful model organism to address fundamental landscape ecology questions that have application to pest management. Results demonstrate that flour patch distribution influences how female red flour beetles move and how eggs are distributed. This information coupled with other ongoing studies related to population consequences of these egg laying decisions will provide insight into the fitness consequences of landscape pattern and ultimately how flour mill sanitation affects insect population growth.

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, beetles were shown to be 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. Molecular genetic markers used to determine red flour beetle population structure. Molecular genetic techniques can be used to identify the source of insect infestation and also evaluate the amount of movement among different locations, which has important implications for identifying the sources of infestation in commercial food facilities. Analysis with molecular markers indicates differences among red flour beetle populations collected from different food facilities around the United States, but the level of difference was not correlated with geographic distance, nor with the type of facility, and so provided limited information on insect movement patterns. Initial analysis indicates that populations are similar over time in a flour mill, even after a fumigation. Ability to identify the source of infestation in food distribution channels would be a useful tool to the food and pest management industries.

5. Stored-product insect distribution outside food processing facilities. Accumulation of spillage material and presence of alternative food sources in the environment around a food facility may serve as refugia for insects moving into and out of food processing facilities. At food processing facilities, more insects were captured inside compared to the outside, but most species could be found both inside and outside. Insects captured outside tended to be associated with outer perimeter of structures and were not necessarily associated with food spillage or any other habitat type. Management of the environment around a food facility is an important part of an IPM program and this research provides some of the first insight into how stored-product insects use this environment.

6. Simulation model for 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. With the phase-out of methyl bromide for fumigation, the milling industry needs new alternatives and treatment strategies. ARS scientists in Manhattan, Kansas developed a computer model for the red flour beetle in flour mills. 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. Findings from this study will be used to develop optimal treatment programs for flour mills using alternative methods such as heat and sulphuryl fluoride.

7. Insecticides for Control of Psocids in Stored Grain. Psocids, or booklice, are emerging pests in stored products, including stored grains. Currently, their control is based on the use of fumigants and contact insecticides; however, newer data indicate that psocids are tolerant to insecticides used to control other stored-grain insect pests. In this study, ARS scientists in Manhattan, Kansas, evaluated the insecticides registered in the U.S. for use on stored corn, rice, and wheat for control of the psocid species Lepinotus reticulatus, Liposcelis entomophila, L. bostrychophila, and L. paeta. On wheat and rice, chlorpyriphos-methyl + deltamethrin was generally more effective in controlling adults and reducing progeny production than spinosad or pyrethrum, while pirimiphos-methyl was more effective on corn than spinosad or pyrethrum. In most cases, progeny production was suppressed in all treated grains. Chlorpyriphos-methyl + deltamethrin and pirimiphos-methyl were the most effective insecticides for all species and commodities for which they are registered. Efficacy of spinosad or pyrethrum was dependent on the psocid species and commodity. This information will help grain storage managers select protectant insecticides for psocid control.

8. Development of Methods for Sampling Psocids in Stored Grain. Psocids, or booklice, are emerging pests of stored grain and processed stored products, but little is known about how to sample them to determine their population levels to aid in making pest management decisions. ARS scientists in Manhattan, Kansas, compared five methods for sampling psocids in wheat stored in steel bins: cardboard refuges on the surface of the grain and on the bin hatch, grain samples taken using a grain trier probe, and automated sampling using StorMax Insector™ electronic probe traps. Two species of psocids were identified during the study: Liposcelis entomophila in 2005 and L. decolor in 2006. In general, the five sampling methods reflected similar patterns in seasonal abundance of psocids in both years, except that no psocids were found in the hatch refuges in December to February when temperatures were low. Psocid densities in cardboard refuges and in Insector™ probes correlated well with psocid densities in grain samples in both years. The results indicate that cardboard refuges or Insectors™ may provide an effective method for sampling psocids in bins of wheat. This information should be useful for the development of sampling plans which can be used to time psocid management in stored wheat.

9. Spinosad as a Surface Treatment for Control of Insects in Stored Grain. In bulk grains, most of the insect infestation occurs in the top layer of the grain mass so ARS scientists in Manhattan, Kansas, evaluated the effectiveness of a new biological insecticide, Spinosad, as a surface treatment in wheat to control adults of five common species of stored-grain insect pests. Spinosad was applied to the upper one half, one fourth, or one eighth layer of the wheat or the entire grain mass in a vial, and insects were either added to the vials before or after the wheat. When lesser grain borers were added to the vials after the wheat, all insects died except in the one-eighth layer treatment. In contrast, when adults were placed in the vials before the wheat, all insects died only when all of the wheat was treated. Mortality of the rice weevil was lower but there was evidence of upward movement into the treated layers. Mortality of the psocids Liposcelis paeta and L. bostrychophila was <50% when the entire quantity was treated, in contrast to 100% mortality of the psocid Lepinotus reticulatus. However, for all psocid species, overall mortality decreased with decreasing depth of the treated layer. The results of this laboratory study show that while spinosad has some effectiveness as a partial treatment to wheat, efficacy will depend on the target species, the depth of the treated layer, and the upward or downward mobility of the insect species; thus, this is not a promising use of Spinosad.

10. Short-Term Exposure to Spinosad for Control of Stored-Grain Insects. Insecticides are one tool for controlling insect pests of stored grain, but we are losing many stored-grain insecticides because of insect resistance and registration issues. ARS scientists in Manhattan, Kansas, evaluated control of four insect pests of stored wheat and corn after short exposures to a new insecticide, spinosad, which has low mammalian toxicity. Short exposures may occur because a grain bulk may not be completely treated with insecticide. The lesser grain borer was very susceptible to spinosad and no progeny were produced after eight hours exposure. There was moderate mortality of adult rice weevils, but progeny production was not impacted by spinosad. Spinosad had little effect on red flour beetles or the psocid Lepinotus reticulatus. The lesser grain borer is the most important pest of wheat, so even short-term exposure to spinosad will provide good control.


6.Technology Transfer

Number of the New/Active MTAs (providing only)6

Review Publications
Romero, S., Campbell, J.F., Nechols, J.R., With, K.A. 2008. Movement behavior in response to landscape structure: the role of functional grain. Landscape Ecology. 24(1): 39-51. Doi: http://dx.doi.org/10.1007/s10980-008-9278-8.

Fushing, H., Shapiro Ilan, D.I., Campbell, J.F., Lewis, E. 2008. State-space based mass event-history model I: many decision-making agents with one target. Annals of Applied Statistics. 2:1503-1522.

Nansen, C., Meikle, W.G., Campbell, J., Phillips, T.W., Subramanyam, B. 2008. A binomial and species-independent approach to trap capture analysis of flying insects. Journal of Economic Entomology vol 101,pages 1719-1728.

Opit, G.P., Throne, J.E., Flinn, P.W. 2009. Temporospatial Distribution of the Psocids Liposcelis entomophila and L. decolor in Steel Bins Containing Wheat. Journal of Economic Entomology 102: 1369-1376.

Opit, G.P., Throne, J.E., Flinn, P.W. 2009. Evaluation of Five Sampling Methods for Liposcelis entomophila (Enderlein) and L. decolor (Pearman) (Psocoptera: Liposcelididae) in Steel Bins Containing Wheat. Journal of Economic Entomology 102: 1377-1382.

Shapiro Ilan, D.I., Campbell, J.F., Lewis, E.E., Elkon, J.M., Kim-Shapiro, D.B. 2009. Directional movement of parasitic nematodes in response to electrical current. Journal of Invertebrate Pathology. 100:134-137.

Christen, J.M., Campbell, J.F., Zurek, L., Shapiro Ilan, D.I., Lewis, E.E., Ramaswamy, S.B. 2008. Role of symbiotic and non-symbiotic bacteria in carbon dioxide production from hosts infected with Steinermena riobrave. Journal of Invertebrate Pathology. 99(1): 35-42. Doi: http://dx.doi.org/10.1016/j.jip.2008.05.008.

Guedes, R.N., Campbell, J.F., Arthur, F.H., Opit, G.P., Zhu, K., Throne, J.E. 2008. Acute lethal and behavioral sublethal responses of two stored-product psocids to surface insecticides. Pest Management Science. 64(12): 1314-1322. Doi: http://dx.doi.org/10.1002/ps.1634.

Jia, F., Toews, M.D., Campbell, J.F., Ramaswamy, S.B. 2008. Survival and reproduction of lesser grain borer, Rhyzopertha dominica (F.)(Coleoptera: Bostrichidae) on flora associated with native habitats in Kansas. Journal of Stored Products Research. 44(4): 366-372. Doi: http://dx.doi.org/10.1016/j.jspr.2008.06.001.

Opit, G.P., Throne, J.E., Flinn, P.W. 2009. Sampling Plans for the Psocids Liposcelis entomophila (Enderlein) and L. decolor (Pearman) (Psocoptera: Liposcelididae) in Steel Bins Containing Wheat. Journal of Economic Entomology 102: 1714-1722.

Athanasiou, C.G., Arthur, F.H., Opit, G.P., Throne, J.E. 2009. Insecticidal Effect of Diatomaceous Earth Against Three Species of Stored-Product Psocids on Maize, Rice, and Wheat. Journal of Economic Entomology 102: 1673-1680.

Nowaczyk, K., Obrepalska-Steplowsk, A., Gawlak, M., Throne, J.E., Olejarski, P., Nawrot, J. 2009. Molecular Techniques for Detection of Confused Flour Beetle Infestations in Stored Products. Journal of Economic Entomology 102: 1691-1695.

Guedes, R.N., Zhu, K., Opit, G.P., Throne, J.E. 2008. Differential Heat Shock Tolerance and Expression of Heat-Inducible Proteins in Two Stored-Product Psocids. Journal of Economic Entomology 101: 1974-1982.

Opit, G.P., Throne, J.E. 2009. Population Growth and Development of the Psocid Liposcelis brunnea Motschulsky (Psocoptera: Liposcelididae) at Constant Temperatures and Relative Humidities. Journal of Economic Entomology 102: 1360-1368.

Flinn, P.W., Opit, G.P., Throne, J.E. 2009. Predicting Stored Grain Insect Population Densities Using an Electronic Probe Trap. Journal of Economic Entomology 102: 1696-1704.

Last Modified: 10/26/2014
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