A new tool in biological control: parasitoid acclimation

Acclimation of natural enemies is a serious problem, when bio-control agents are introduced into different climatic zones, for which they are not adapted. Microorganisms typically experience a wide range of tolerance to climate condition (i.e. E. coli). The phylogenetic relatedness of secondary symbiotic bacteria (SSB) of aphids to E. coli may explain their contribution to thermal tolerance in aphids as well. Regiella insecticola (PAUS), Hamiltonella defensa (PABS), and Serratia symbiotica (PASS), common secondary endosymbionts found in different aphid species are known to confer (at least partially) thermal tolerance to individuals harboring them. We hypothesized that the use of parasitoids as biocontrol agents can be optimized when acclimated to specific environmental conditions by infecting them with a set of these specific bacteria. We show that SSBs are transferred to aphid parasitoids during host feeding or larval development. Moreover, SSB infected parasitoids benefit from infections at different temperature regimes, increasing their fitness.