Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2009
Publication Date: 7/15/2009
Citation: 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. Interpretive Summary: Psocids, or booklice, are emerging pests of stored grain and processed stored products, but we know little about their biology and control. We evaluated the effectiveness of three insecticidal diatomaceous earth (DE) formulations that are registered for control of stored-product insects, Dryacide, Protect-It, and Insecto, against three psocid species, Liposcelis entomophila, Lepinotus reticulatus, and Liposcelis decolor on wheat, rice and corn in the laboratory. Liposcelis decolor was relatively tolerant of all DEs. Susceptibility of Liposcelis entomophila and Lepinotus reticulatus varied with grain and DE formulation. Mortality of L. entomophila, L. reticulatus, and L. decolor was only 63, 71, and 42%, respectively, after 14 days, and offspring production after 30 d reached 54, 42, and 76 individuals per 10 g of grain. Our results indicate that DE’s, when used alone, will not provide effective control of psocids.
Technical Abstract: We evaluated the efficacy of three diatomaceous earth (DE) formulations, Dryacide, Protect-It, and Insecto, against three Psocoptera species, Liposcelis entomophila (Enderlein) (Liposcelididae), Lepinotus reticulatus Enderlein (Trogiidae), and Liposcelis decolor (Pearman) in the laboratory. Bioassays were conducted in three grain commodities, wheat, rice and maize, at 30°C and 75% RH, and the DEs were applied at the recommended dose rates of 1000, 400 and 500 ppm, for Dryacide, Protect-It and Insecto, respectively. Differences in adult mortality were found among grains and DEs for L. entomophila and L. reticulatus, but these trends were not consistent for all combinations tested. Type of grain and DE did not affect L. decolor mortality significantly. Moreover, mortality increased with increasing exposure time for L. entomophila and L. reticulatus, but there was no effect of exposure time on L. decolor. After 7 d of exposure, mortalities of L. entomophila, L. reticulatus, and L. decolor were 56, 55, and 40%, respectively, and the respective mortality levels after 14 d were 63, 71, and 42%. Progeny production after 30 d was significantly suppressed for all species in the treated grains. However, progeny production was still high in the treated grains, and reached 54, 42, and 76 individuals/10 g of grain for L. entomophila, L. reticulatus, and L. decolor, respectively. Progeny production did not vary with commodity. Our results suggest that DE’s, when used alone, will not provide effective control of psocids.