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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 Title: Sampling Plans for the Psocids Liposcelis entomophila (Enderlein) and L. decolor (Pearman) (Psocoptera: Liposcelididae) in Steel Bins Containing Wheat

Authors
item Opit, George
item Throne, James
item Flinn, Paul

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 14, 2009
Publication Date: July 15, 2009
Citation: 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.

Interpretive Summary: Psocids, or booklice, are emerging pests of stored grain and processed stored products, but no sampling methods for estimating their population levels have been developed to aid in making pest management decisions. We developed methods for sampling Liposcelis entomophila and L. decolor in wheat stored in steel bins using cardboard refuges placed on the surface of the grain. Numerical sampling, where psocids found in refuges are counted, and presence-absence sampling, where the proportion of infested refuges is determined, were found suitable for estimating psocid population levels. We recommend that numerical sampling be used at densities of less than 10 psocids/refuge, and that 20 refuges be placed in each bin. At densities higher than 10 psocids/refuge, we recommend that presence-absence sampling be used with 20 refuges/bin. In a mixed infestation of the two species, we suggest that only numerical sampling be used because of the large number of samples required. The sampling methods we have developed based on the use of cardboard refuges are convenient for use in steel bins containing wheat because they are inexpensive, provide a rapid assessment of psocid population incidence, and are easy to implement. These sampling plans can be used to monitor populations of and the efficacy of management strategies used against L. entomophila and L. decolor.

Technical Abstract: Psocids are an emerging problem in grain storage, handling, and processing facilities in the United States. We used data from two steel bins each containing 32.6 metric tonnes of wheat to develop sampling plans for Liposcelis entomophila, L. decolor, and a mixture of the two. Taylor’s coefficients “a” (a sampling factor) and “b” (an index of aggregation) for these pests were calculated with the aid of bootstrapping. The optimal binomial sample sizes for estimating populations of these psocids at densities of less than 10 psocids/refuge were large; therefore, we recommend the use of numerical sampling within this range of densities. Numerical sampling of L. entomophila and L. decolor at densities of less than 10 psocids/refuge should not be too laborious given the low psocid numbers involved; we recommend using 20 refuges/bin. For presence-absence sampling of L. entomophila or L. decolor, 20 refuges/bin should be used at densities of 10 or more psocids/refuge. In a mixed infestation, we suggest that only numerical sampling be used because the lowest binomial sample size for densities of 10 or more psocids/refuge is 66 refuges/bin, and this is not practical. The sampling plans we have developed based on the use of cardboard refuges are convenient for use in steel bins containing wheat because they are inexpensive, provide a rapid assessment of psocid population incidence, and are easy to implement. These sampling plans can be used to monitor populations of and the efficacy of management strategies used against L. entomophila and L. decolor.

Last Modified: 11/26/2014
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