Host Plant Quality Influences Diapause Induction of <I>Byasa alcinous</I> (Lepidoptera: Papilionidae)

Abstract

Using host plant quality as a diapause-inducing stimulus may be adaptive for herbiv- orous 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 buttersy Byasa alcinous Klug (Lepidoptera: Papilionidae). We also conducted Þeld 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 Þeld, leaf age composition in A. kaempferi was greatly insuenced 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.