Microplitis demolitor and Microplitis demolitor bracovirus (MdBV)

Microplitis demolitor is a wasp that parasitizes lepidopteran hosts.

This wasp belongs to the Microgastroid complex of parasitoids that have viral symbionts with double-stranded DNA genomes from the genus Bracovirus (Polydnaviridae).

Bracoviruses infect caterpillar hosts and express genes that alter the host’s immune system and metabolism, which is essential for development of the wasp’s offspring (see life cycle below).


Bracoviruses replicate in specialized cells in wasp ovaries, and accumulate to massive levels throughout development.

During pupal development, wasp ovaries slowly grow in size and virus accumulates in the calyx region.

Features of an adult wasp ovary. Photo credit: Jena Johnson.
A final-stage wasp larva, then four pupal stages. The wasp ovaries slowly grow in size and accumulate virus in the calyx region.
A final-stage larva and four pupal stages of development. Line drawings of ovary morphology are shown beneath each developmental stage. Photo credit: Jena Johnson.