Liposcelis obscurus Broadhead (Psocoptera: Liposcelididae) Ecology and Dehumidification for Psocid Management

Abstract

Psocids (Psocoptera) have become more economically important as serious pests of stored-products worldwide in the last two-to-three decades. However, knowledge on their ecology and biology which is crucial for the development of effective management strategies is lacking. In this study, I investigated the effects of constant temperatures and relative humidities (RH) on the population growth and development of L. obscurus. I also investigated the effects of low RH on the survival of four psocid species. This research shows that L. obscurus can survive and multiply at a low relative humidity of 55% at temperatures of 22.5–27.5°C and a high temperature of 42.5°C at 75% RH. The optimal conditions for multiplication for this species are 40.0°C and 75% RH where population growth was a 215-fold from an initial population of five adults. The optimum temperature for development is 40.0°C and requires 15.8 d to develop from egg to adult. L. obscurus had three to five nymphal instars. Temperature had significant effect on development time for all developmental stages. I developed temperature-dependent equations for L. obscurus developmental stages which can be used to elucidate its population dynamics. Also, my data from the effects of low RH on psocid survival demonstrated that psocids can be managed using dehumidification (a physical control method). At 43 or 50% RH, at least 8–16 d will be required to control all developmental stages of L. bostrychophila, L. decolor, L. entomophila, and L. paeta depending on the species. My data on L. obscurus ecology and the effects of low RHs on the survival of psocids will facilitate the development of strategies that can play a significant role in the integrated management of psocids.