Parasitic wasps do not lack lipogenesis.

Fatty acids are crucial primary metabolites for virtually all creatures on earth. Most organisms thus do not rely exclusively on a nutritional supply containing fatty acids, but have the ability to synthesize fatty acids and triacylglycerides de novo from carbohydrates in a process called lipogenesis. The ubiquity of lipogenesis has been questioned by a series of studies reporting that many parasitic wasps (parasitoids) do not accumulate lipid mass despite having unlimited access to sugar. This has been interpreted as an evolutionary metabolic trait loss in parasitoids. Here, we demonstrate de novo biosynthesis of fatty acids from 13C-labelled α-d-glucose in 13 species of parasitoids from seven families. We furthermore show in the model organism Nasonia vitripennis that lipogenesis occurs even when lipid reserves are still intact, but relative 13C-incorporation rates increase in females with widely depleted fat reserves. We therefore conclude that the presumed 'lack of lipogenesis' in parasitoids needs to be re-evaluated.