Influence of ambient temperature and relative humidity on changes in numbers of a natural population of Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae)

Tobacco processing practices of humidifying rooms with mist and using steam to soften cured leaf, raise relative humidity (r.h.) and temperature in the rooms during February to March, creating conditions suitable for Liposcelis entomophila multiplication. High r.h. values and high temperatures in these buildings corresponded with the annual peak in booklice numbers. The number of booklice trapped in the period preceding the annual peak was found to be linearly related to cumulative degree-days calculated excluding days when r.h. and temperature were below 70% and 18 degrees C, respectively. Elevation of r.h. and temperature during processing also promotes fungal growth, making more food available for the booklice. It is suggested that L. entomophila numbers in tobacco processing buildings can be reduced by manipulating r.h. and temperature to levels below 70% and 18 degrees C, respectively.