Survival of stored-product psocids (Psocoptera: Liposcelididae) at 43% and 50% relative humidity

Abstract: The psocid species Liposcelis entomophila (Enderlein), Liposcelis decolor (Pearman), Liposcelis bostrychophila Badonnel and Liposcelis paeta Pearman are well recognized stored-product pests that infest grain storage facilities and warehouses worldwide. Psocids are pests of substance and their economic importance is documented. Pest management practices designed to control coleopteran and lepidopteran pests have been less successful against psocids. Psocids are quite sensitive to low relative humidity. Therefore, moisture management and dehumidification can be effective alternative tools for their control. In the present study, we investigated the effects of 43 and 50% relative humidity on the survival of the above mentioned four Liposcelis species. Survival of all life stages of the four species of psocids at 43 and 50 and at 75% RH was determined after 0, 2, 4, 8, 10, 12, 14 and 16 d at 30 °C. At 43% RH, 100% mortality of all stages of L. entomophila, L. decolor, L. bostrychophila, and L. paeta occurred after 8, 8, 10 and 12 d, respectively. At 50% RH, 100% mortality of all life stages of L. entomophila, L. decolor, L. bostrychophila and L. paeta occurred after 10, 12, 14 and 16 d, respectively. Over the 30-d period of the experiment, at 75% RH, numbers of nymphs and adults of all the four species increased. These data indicate that dehumidification has good potential for use in psocid management under specific conditions where it can be effectively and practically deployed.