Freezing for control of stored-product psocids

Authors: Arthur, Franklin; Hartzer, Kris; Throne, James; FLINN, PAUL - Retired ARS Employee

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2016
Publication Date: 3/6/2017
Publication URL: http://handle.nal.usda.gov/10113/5648463
Citation: Arthur, F.H., Hartzer, K.L., Throne, J.E., Flinn, P.W. 2017. Freezing for control of stored-product psocids. Journal of Stored Products Research. 72:166-172. https://doi.org/10.1016/j.jspr.2016.12.005.
DOI: https://doi.org/10.1016/j.jspr.2016.12.005

Interpretive Summary: Psocids are insects that contaminate raw grains and stored food products and are an increasing problem in the United States. They are more difficult to control with the insecticides compared to other stored product pests, so we evaluated whether cold temperature could be used as a disinfestation strategy for psocids. By conducting studies in which different life stages of four major pest psocid species were exposed to 0°F it was determined that eggs of three of the four psocid species we tested were much harder to kill compared to nymphs and adults. Exposure to 0°F for 1 to 2 hours killed all nymphs and adults, while eggs of one species survived up to 128 hours of exposure. Cold temperatures can be incorporated into management programs to protect stored products from psocids, but given the tolerance of eggs, longer exposure times may be needed compared to other stored product insects.

Technical Abstract: A series of studies was conducted by exposing young and old eggs, nymphs, and adults of the psocids Lipocelis bostrychophila (Badonnel), L. paeta (Pearman), L. decolor (Pearman), and L. entomophila (Enderlein) to -18°C for various time intervals. Survival was assessed as initial and final, at different times depending on the life stage. Young eggs of L. bostrychophila were the most tolerant life stage of any of the species, with scattered survival out to 120 hours of exposure to -18°C. Eggs were the most tolerant life stage for each species, requiring 24, 12, and 2 hours of exposure for complete kill of L. paeta, L. decolor, and L. entomphila, respectively. Nymphs and adults of all species were far more susceptible than eggs, with no final survival after two hours of exposure. Results show the extreme variation between different psocid life stages and species to cold temperatures, and provide guidelines for using cold as a control strategy for psocids. Our results show that 24 hours at -18°C is sufficient to kill all life stages of the psocid species tested, except for young L. bostrychophila eggs which will require at least 128 hours of exposure at -18°C for complete mortality.