Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2021
Publication Date: 3/30/2021
Citation: Ocran, A.F., Opit, G.P., Noden, B.H., Arthur, F.H., Kard, B.M. 2021. Effects of dehumidification on the survivorship of four psocid species. Journal of Economic Entomology. 114(3):1380-1388. https://doi.org/10.1093/jee/toad066.
DOI: https://doi.org/10.1093/jee/toab066

Interpretive Summary: Psocids are small soft bodied insects that are increasing in importance in stored products due to product rejections and contamination issues. They are difficult to kill with insecticides compared to other stored product insects, and alternative control measures are being evaluated for inclusion into management programs. A study was conducted to determine if low humidity could be used as a control strategy. Four psocid species were exposed to 43% and 50% relative humidity (RH). At 43% RH mortality of adults occurred after 8 days but 12 days was required to kill all adults of all species at 50% RH. Longer exposure times were required to kill other life stages, and for one species complete mortality of immature stages was not achieved at 50% RH. Results indicate the potential of using low RH for psocid control, but variation in susceptibility between life stages and between species must be considered when using low RL.

Technical Abstract: Psocids are damaging stored-product pests. In this study, eggs and early instar nymphs, adults, and all life stages of Liposcelis entomophila, L. decolor, L. bostrychophila, and L. paeta were subjected to 43, 50, or 75% (Control) relative humidity (RH) for 2, 4, 6, 8, 10, 12, 14, or 16 d at 30.0°C. All adults of these species died within 8 d at both 43 and 50% RH, except for L. bostrychophila, which required 12 d at 50% RH. For all life stages, and eggs and early instar nymphs, maximum survival times (times to 100% mortality) at 43 or 50% RH for L. entomophila, L. decolor, L. bostrychophila, and L. paeta, were 8 and 10 d, 8 and 12 d, 12 and 14 d, and 12 and 16 d, respectively. During this 30-d study, numbers of nymphs and adults of all species increased within the 75% RH control arenas. Different species and life stages responded differently to 43 and 50% RH, as time to kill all stages of the four psocid species was 8–12 d and 10–16 d, respectively. Results indicate that using a specific RH environment may be effective in psocid management.