THE EFFECT OF REARING TEMPERATURE ON THE SIZE AND FAT CONTENT OF THE DOUGLAS-FIR BEETLE

Abstract

Douglas-fir beetle, Dendroctonus pseudotsugae Hopk., broods developed more rapidly at a constant 21 °C. than at 13 °C. or at the temperature outdoors during the summer. The dry weight and fat content of young larvae developed at 13 °C. were lowest, whereas the dry weight and fat content of adults reared at 13 °C. were highest. Adults reared outdoors had the lowest dry weight and fat content. The differences in weight and accumulated fat are attributed to the effect of temperature on the length of time available for feeding, and on the rate of metabolism in the various developmental stages. Variations in temperature during the prediapause–diapause period also produce changes in the relation between the size and fat content of the adults.