Seasonal phenotypic plasticity of the polyvoltine white butterfly Pieris napi L. (Lepidoptera: Pieridae) in the Southern Urals

Abstract

Seasonal variations in the body weight and the forewing size of imagoes have been studied based on the example of different seasonal generations of the white butterfly Pieris napi L. in the Southern Urals. It has been found that the body weight of imagoes during the flight of one generation decreases in the process of reproduction. In this case, reserve substances in the abdomen are spent most intensively during the life of an insect: as the flight activity of a seasonal generation begins, the mean relative abdominal weight of imagoes is always higher than at the end of its flight. The wings of imagoes in the spring generation are the smallest. Those in the summer generations are the largest. Thus, these generations are capable of long and energy-consuming flights. Therefore, seasonal generations of P. napi are distinguished based on morphophysiological features associated with their fertility and adaptation of imagoes to settle in new habitats.