Population growth and development of the psocid Liposcelis pearmani Lienhard (Psocoptera: Liposcelididae) at constant temperatures and relative humidities

The effects of eight temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0°C) and four relative humidities (43, 55, 63, and 75%) on the population growth of the psocid Liposcelis pearmani Lienhard (Psocoptera: Liposcelididae) were investigated. L. pearmani does not survive at 43% RH, at all temperatures tested, and at all relative humidities tested at temperatures of 37.5 and 40.0°C. L. pearmani populations increased at temperatures between 22.5 and 35.0°C and relative humidities between 55% and 75% RH. Optimal conditions for L. pearmani population growth were 32.5°C and 75% RH; at these conditions population increased 31-fold in 30 days. L. pearmani females have two to five instars and the percentages of females with two, three, four, and five instars were 5, 39, 54, and 2%, respectively. Temperature-dependent development equations for female eggs, individual nymphal, combined nymphal, and combined immature stages were developed for L. pearmani. Contrary to some published reports indicating that Liposcelis species cannot survive below 60% RH, our study revealed that L. pearmani populations can grow at 55% RH. Our data can be used to predict L. pearmani occurrence and population dynamics, and for the development of effective management techniques.