Sibling species of the Cotesia inducta complex (Hymenoptera: Braconidae) sympatrically parasitising heterogeneous lycaenid larvae associated with ants

Abstract

Approximately 75% of lycaenid butterfly species in the world associate with ants during their larval stages to gain protection against natural enemies such as parasitoids. Despite intensive studies on lycaenid–ant interactions, parasitoids exploiting myrmecophilous hosts remain poorly understood, thereby limiting our understanding of the eco-evolutionary dynamics of parasitoid–host interactions. Here, three sibling species of Cotesia Cameron (Hymenoptera: Braconidae) parasitising ant-associated lycaenid larvae in Japan were identified, and their ecological differentiation within this parasitoid group was investigated. We propose the Cotesia inducta complex, comprising Cotesia inducta (Papp), Co. sp. aff. inducta and Co. suzukii sp. nov. Co. inducta is recorded from Japan (Honshu) for the first time, and Co. suzukii sp. nov. is described and illustrated from Japan (Honshu and Kyushu). Co. suzukii sp. nov. is a specialist parasitoid of Arhopala japonica (Murray) (Theclinae) on Quercus spp., whereas Co. inducta exhibits a broad host range across multiple lycaenid subfamilies (Curetinae, Polyommatinae and Theclinae) in Europe and Japan. Mitochondrial DNA analyses reveal the monophyly of the Co. inducta complex, as well as that of Co. inducta and Co. suzukii sp. nov. Both species are multivoltine; however, Co. inducta exploits different host species seasonally, whereas Co. suzukii sp. nov. consistently utilises Ar. japonica. Moreover, Co. inducta primarily parasitises flower-feeding hosts, whereas Co. suzukii sp. nov. only uses leaf-feeding hosts, indicating that host-feeding habitat contributes to diversification within the Co. inducta complex. These findings provide fundamental ecological information on parasitoids associated with myrmecophilous butterflies.