COSTS AND BENEFITS OF ACCLIMATION TO ELEVATED-TEMPERATURE IN TRICHOGRAMMA-CARVERAE

The consequences of acclimation for survival and other fitness compone nts in the parasitoid wasp, Trichogramma carverae (Oatman and Pinto), were examined. Heat hardening adult wasps at 33 degrees C or 35 degree s C for one to two h increased survivorship at 40 degrees C. This bene fit was apparent for several hours after heat-hardening and occurred i n both males and females. Heat hardening at 33 degrees C during develo pment also resulted in significant increases in survivorship of adults after exposure to 40 degrees C. However, this developmental hardening reduced longevity of adult male and female wasps and also reduced par astism rate. This suggests costs and benefits of exposure to non-letha l temperature increases. Acclimating wasps by rearing them under const ant temperatures (14, 25 or 30 degrees C) influenced parasitism rates at these temperatures at the adult stage; only females reared at 14 de grees C parasitised eggs at 14 degrees C, while parasitism at 25 degre es C and 30 degrees C was not significantly influenced by rearing temp erature. Acclimation may be useful for increasing the survival or fecu ndity of mass-reared Trichogramma in inundative releases, but any bene fits could be offset by fitness costs of the acclimation process.