The specificity of behavioral fever in the cricket Acheta domesticus

When infected, some insects can raise their body temperature by moving to warmer areas. This behavioral fever response can help the host overcome infection. However, not all parasites and pathogens are equally susceptible to increases in host temperature. Elevating the temperature of the cricket Acheta domesticus from room temperature (22 C) to 33 C did not reduce the survival of parasitoid flies or reduce the number of gregarine gut protozoans, and crickets infested with these parasites showed no increase in their temperature preference. Warmer temperatures (33 C) did not increase the survival of crickets infected with the bacterium Serratia marcescens, and infected crickets did not prefer warmer temperatures. However crickets infected with the intracellular parasite Rickettsiella grylli were more likely to survive when the host was exposed to warmer temperatures. Crickets infected with R. grylli increased their preferred temperature from 26 C to 32 C. In A. domesticus, behavioral fever may be a specific response induced by relatively few pathogens and parasites. Behavioral fever in insects may differ in this respect from fever in mammals that can be elicited by a wide variety of parasites and pathogens.