Longevity, flight ability and reproductive performance of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae), related to adult body size

Plutella xylostella in the temperate zone shows a clear seasonal change in adult body size. In the laboratory, large and small moths were produced during immature stages at 15°C and 25°C, respectively. These moths were then used to evaluate longevity, age‐specific flight ability, flight ability of mated and unmated females, and the influence of flight experience on the subsequent reproductive success. The large moths lived longer and displayed a greater flight ability over 3 weeks. Irrespective of body size, unmated females flew for a longer time than mated females, and flight experience affected their subsequent reproductive success. Females of both sizes mated and laid eggs soon after emergence, without any obvious pre‐reproductive period. More flight experience did not delay oviposition, but did reduce egg production. It is likely that large moths with a longer adult life span and greater flight ability are better fitted for long‐distance flight and more fecund than small ones. These experimental results may explain why long‐distance migration of P. xylostella is mostly seen during cool seasons, when relatively large moths with long forewing appear in the field.