Host-castration
Guides
Aphidius ervi
Aphidius ervi is a parasitoid wasp in the subfamily Aphidiinae, widely distributed globally and extensively used in biological control programs against aphid pests. It parasitizes larger aphid species, particularly Macrosiphum euphorbiae (potato aphid) and Aulacorthum solani (foxglove aphid), and to a lesser extent Acyrthosiphon pisum (pea aphid). The wasp induces host castration and immunosuppression through venom proteins, allowing its larva to develop within the living aphid until emerging from a characteristic 'aphid mummy' by chewing a round exit hole.
Ascogaster
Ascogaster is a genus of braconid wasps comprising egg-larval endoparasitoids that attack tortricid moth pests. Females oviposit into host eggs, and developing wasp larvae consume host reproductive organs—a process termed host castration—before eventually killing the host. This developmental strategy redirects host resources from reproduction to somatic growth, increasing host size and improving conditions for parasitoid development. Several species have been studied for biological control applications, particularly against the codling moth (Cydia pomonella) and smaller tea tortrix (Adoxophyes spp.).