Fertilization of hetero-specific insect eggs by sperm injection

Mature eggs dissected from the ovary of unmated sawflies (Tenthredinidae, Hymenoptera) can be activated to develop (to haploid males), simply by placing on a filter paper wet with distilled water. These unfertilized eggs may be injected with sperm, and some, successfully completing fertilization, develop as diploid females. Premating reproductive isolation exists between two sympatric species of this family, Athalia rosae ruficornis Jokovlev and Athalia infumata Marlatt. Taking advantage of the difference in karyotypes, it is shown that hetero-specific sperm injection results in successful fertilization and that the hybrid survives at least through the middle stage of embryogenesis.