Lower survival rate of a threatened butterfly, Plebejus argyrognomon (Bergstrasser) (Lepidoptera, Lycaenidae) on a naturalized plant, Melilotus officinalis alba

Abstract

In Nagano City and Ueda City, Nagano Prefecture, a threatened lycaenid butterfly, Plebejus argyrognomon was observed to lay eggs on and feed on the non-native host plant, Melilotus officinalis alba, which was naturalized from Central Asia to Japan. Larvae reared on M. officinalis alba could be reared to adult stage by indoor breeding. The survival rate was 2.8% reared on M. officinalis alba and 83.3% on the native host, lndigofera pseudo-tinctoria. Furthermore, the developmental period from the early larval stage to the pupa was 61.5 days (n=2) reared on M. officinalis alba and 34.6±2.4 days (n=5) on I. pseudo-tinctoria. These results suggest that the invasion of M. officinalis alba might reduce the survival rate of P. argyrognomon.