Eicosanoid involvement in the regulation of behavioral fever in the desert locust, Schistocerca gregaria

Abstract

The desert locust Schistocerca gregaria behaviorally thermoregulates in order to try and maintain a favoured "set point" body temperature. Locusts infected with the deuteromycete fungal pathogen Metarhizium anisopliae var acridum choose a significantly elevated temperature. This "behavioral fever" greatly delays the progress of mycosis. We have confirmed this phenomenon and shown that desert locusts also fever when infected with the bacterial pathogen Serratia marcescens. Elevation in the prefered environmental temperature occurs also upon injection with laminarin and lipopolysaccharide (microbial cell wall components). Since such treatments also stimulate the immune system it would appear that "behavioral fever" is probably a feature of the immune response. The eicosanoid biosynthesis inhibitor dexamethasone prevented laminarin invoked fever. This effect was reversoble by arachidonic acid. Therefore in common with the febrile response in mammals behavioral fever in insects may be mediated locally by circulating eicosanoids. © 2003 Wiley-Liss, Inc.