Crowding has a detrimental impact on the behavioral, developmental, growth and reproductive processes of all animals especially vertebrates and insects. Even when all other environmental conditions are optimal, crowding, defined as high population density rearing, usually evokes a stress response in these processes. Since the operation of these precesses relies on underlying physiological and molecular mechanisms, crowding must be stimulating a stress response in these mechanisms. However, the physiological and molecular mechanisms through which crowding influences these processes are not well known. One approach to examining the impact of crowding on a neurohormonal mechanism is to examine each component of the mechanism separately. In this way, the response of the neuroendocrine gland can be separated from that of the target systems. This approach can be accomplished with the adipokinetic hormonal mechanism of Anticarsia gemmatalis because each component of the mechanisms is well characterized and this noctuid moth exhibits a strong behavioral and adipokinetic hormonal response to crowding. The applicants working hypothesis is that the enhanced lipid mobilizing capability of crowded insects is due to its influence on components of the adipokinetic hormonal mechanism associated with the level of the peptide hormone in hemolymph, the response/receptivity of the target systems to the hormone, or both.
