The endosymbiotic bacterium Wolbachia (Rickettsiales) alters larval metabolism of the parasitoid Habrobracon hebetor (Hymenoptera: Braconidae)

Abstract

Infection of intestinal tissues with Wolbachia has been found in Habrobracon hebetor. There are not many studies on the relationship between Habrobracon and Wolbachia, and they focus predominantly on the sex index of an infected parasitoid, its fertility, and behavior. The actual role of Wolbachia in the biology of Habrobracon is not yet clear. The method of complete eradication of Wolbachia in the parasitoid was developed here, and effects of the endosymbiont on the host's digestive metabolism were compared between two lines of the parasitoid (Wolbachia-positive and Wolbachia-negative). In the gut of Wolbachia⁺ larvae, lipases' activity was higher almost twofold, and activities of acid proteases, esterases, and trehalase were 1.5-fold greater than those in the Wolbachia^– line. Analyses of larval homogenates revealed that Wolbachia⁺ larvae accumulate significantly more lipids and have a lower amount of pyruvate as compared to Wolbachia^– larvae. The presented results indicate significant effects of the intracellular symbiotic bacterium Wolbachia on the metabolism of H. hebetor larvae and on the activity of its digestive enzymes.