2022 Volume 66 Issue 4 Pages 135-147
The mulberry tiger moth, Lemyra imparilis（Butler）（Lepidoptera: Erebidae）, is a univoltine species that is widely distributed across Japan. Patterns in its population fluctuations and mortality caused by parasitoids and pathogens acting on the post-overwintering larvae were investigated in three areas of Japan. In the Kinki region, where the population follows a seven-year cycle, mortality caused by the parasitoid complex（mainly Hyposoter vierecki［Ichneumonidae］and Carcelia rasa［Tachinidae］）decreased with the L. imparilis population density, while mortality caused by pathogens（mainly Nucleopolyhedrovirus［NPV］）increased with the population density. The southern Nagano Prefecture population was stable, with a low density, and mortality caused by C. rasa and NPV tended to increase with the population density of L. imparilis. On Hachijo Island the population was stable with a high density, and the parasitoid fauna was poor compared to that of Honshu Island. Mortality caused by pathogens, mainly NPV, increased with the population density, and the rate of the population increase decreased linearly with the mortality. This study indicated that the mode of action of parasitoids and pathogens affected the patterns in L. imparilis population fluctuations.
