Pest management of psocids in milled rice stores in the humid tropics

Psocids (Liposcelis spp.) are often abundant in tropical storage systems where very large populations can develop relatively soon after fumigation treatments. In order to improve pest management strategies against these pest some factors governing the potential of psocid populations to increase under tropical conditions were investigated in a large‐scale milled rice store and in the laboratory. The factors studied included the success of pest control, rice milling degree, fungal growth and variations in ambient temperature and humidity. Fumigation failure and low milling degree of the rice stock were confirmed as important factors encouraging rapid and substantial psocid population growth while fungal infection rates, routine spraying of store and bag stack and variations in ambient climatic conditions made no obvious contribution to observed fluctuations in psocid numbers. Suggestions are made for improved pest management strategies that need to be tested under operational conditions.