endoparasitoids

Endoparasitoids are parasitoids that develop inside the body of their arthropod host, in contrast to ectoparasitoids that feed from the outside. They represent a major life-strategy among many insect groups and play a central role in natural pest control.

In typical endoparasitoid life cycles, the female lays eggs or injects first-stage larvae into or onto a suitable host. The larva hatches inside the host and feeds on host tissues or hemolymph, often avoiding rapid host death until later development. Eventually the parasitoid pupates and emerges, leaving behind a dead or severely weakened host.

Taxa that include endoparasitoids are widespread, especially among Hymenoptera such as ichneumonid, braconid, and chalcidoid wasps, and among Diptera such as tachinid flies. Some strepsipterans and other insect orders also include endoparasitoids.

Endoparasitoids can be idiobiont, keeping the host from further development by immobilizing it at oviposition, or koinobiont, allowing the host to continue development while the parasitoid larva grows. The two strategies influence host longevity, host immune responses, and the timing of emergence.

Because of their specificity and effectiveness at suppressing pest populations, endoparasitoids are extensively used in biological control. Notable examples include Encarsia formosa against whiteflies and Trichogramma species against insect eggs, though successful deployment depends on matching parasitoid traits to the target pest.

Interaction with hosts often involves immune suppression and behavioral manipulation to improve parasitoid survival and dispersal, illustrating complex coevolutionary relationships between endoparasitoids and their hosts.