Role of temperature in the biology and control of stored product insects
Abstract: Insects are affected by temperature in all aspects of their biology: ecology, reproduction, behaviour, physiology and biochemistry. Stored product insects reproduce between 20 and 33 °C, with maximum reproduction occurring at approximately 33 °C. Above and below these temperatures insects can move, but cannot complete their development. Temperatures below 3 °C and above 40 °C insects cannot walk, and will eventually die. Between -10 and -25 °C insects freeze and die instantaneously. There are significant changes to these general patterns depending upon species, life stage and acclimation. For example, insects can become 10 times more resistant to cold if acclimated at cool temperatures (5-15 °C) before being exposed to sub-zero temperatures. The speed and direction of movement is affected by temperature. The implications for trapping and sampling are discussed.Examples of using low and high temperature to control insects are given. In general insecticides work better at higher temperatures, but some insecticides have only a small increase in efficacy (methyl bromide), whereas others have a decrease in efficacy (pyrethrins) with higher temperatures.