Lack of lipid accumulation in two species of Chalcidoid wasps with secondarily evolved phytophagy

Stable co-evolutionary relationships between species can result in the loss of autonomous synthesis of essential nutrients when these can be obtained from the ecological partner. Parasitoid insects obtain the majority of their nutrients from their host, and contain multiple, independently-evolved lineages that do not increase their adult lipid reserves despite feeding on a surplus of dietary sugars, although some parasitoid species in these lineages were found to have reactivated adult lipogenesis. Several clades within the parasitoid insects have lost the parasitoid lifestyle and switched to either a predatory or a phytophagous lifestyle. Here, we test whether adult lipid accumulation is reactivated in two species that independently evolved a phytophagous lifestyle from parasitoid ancestors. The larvae of Megastigmus aculeatus (Hymenoptera: Chalcidoidea: Torymidae) and Bruchophagus platypterus (Hymenoptera: Chalcidoidea: Eurytomidae) obligatorily feed on seeds of specific plants. Seeds...