Wolbachia-induced feminisation newly found in Eurema hecabe, a sibling species of Eurema mandarina (Lepidoptera: Pieridae)

1. Complete feminisation of genetic males into functional females, a unique case among insects, is known in Eurema mandarina ( former Eurema hecabe Y type) that are infected with two strains of Wolbachia, wCI(Em) and wFem(Em). 2. Here, we newly found that a proportion of wild-caught E. hecabe (former E. hecabe B type) produced only female offspring. Cytogenetic observations indicated that individuals of E. hecabe displaying the all-female trait were genetically male (i.e. feminisation). 3. Multilocus sequence typing analyses demonstrated that the feminised individuals of E. hecabe were infected with two Wolbachia strains, wCIEh and wFemEh, that were indistinguishable from wCIEm and wFemEm, respectively. 4. Even identical strains of Wolbachia can be regulated differently depending on the host genetic background. Therefore, we compared the infection densities and vertical transmission efficiencies of Wolbachia between feminised E. mandarina and E. hecabe, but detected no significant differences in these traits. 5. The possible routes by which the two Wolbachia strains have transferred between E. mandarina and E. hecabe are discussed.