Host Plant Quality Influences Diapause Induction of Byasa alcinous (Lepidoptera: Papilionidae)

Using host plant quality as a diapause-inducing stimulus may be adaptive for herbivorous insects that use host plants whose phenology is unpredictable based on photoperiod or temperature. We examined the effects of leaf toughness of the woody vine Aristolochia kaempferi Willd. on larval performance and pupal diapause induction of the swallowtail buttery Byasa alcinous Klug (Lepidoptera: Papilionidae). We also conducted eld observations to assess whether human disturbance affects leaf phenology of A. kaempferi. Laboratory experiments showed that tough leaves decreased the survival rate of young larvae and lengthened the larval period, although pupal weight was not affected by leaf toughness. The incidence of pupal diapause was greater with tough leaves than with soft leaves and increased with larval duration. In the eld, leaf age composition in A. kaempferi was greatly inuenced by human mowing, which led to changes in leaf quality. These results suggest that B. alcinous has a plastic diapause strategy using host plant quality as a diapause-inducing stimulus, which may have evolved in frequently disturbed environments.