Impact of carbohydrase inhibition on Habrobracon hebetor in a tritrophic diet-host-parasitoid system

Abstract

Habrobracon hebetor Say (Hymenoptera: Braconidae) is a cosmopolitan idiobiont ectoparasitoid wasp and one of the most important biological control agents of lepidopteran larvae, especially of larvae of the family Pyralidae such as Indian meal moth, Plodia interpunctella (Hübner). Using biological control agents in combination with other pest management approaches may enhance the efficiency of pest management. Acarbose, a non-proteinaceous inhibitor, is well known for its inhibitory effect on insect digestive carbohydrases, especially α-amylase. In the present study the effect of the inhibitor on various physiological and biological parameters of the parasitoid H. hebetor was investigated in a diet-host-parasitoid tritrophic system. The inhibitor decreased α-amylase activity in both in vitro and in vivo assays with the parasitoid; however, there was no significant impact on the biological characteristics studied. Quantification of energy reserves in host larvae and adult parasitoids revealed a dose-dependent effect of the inhibitor on total protein, lipid, carbohydrate, and glycogen contents of the larval host, whereas total protein and carbohydrate of the parasitoid were only reduced at high inhibitor concentrations. In general, the inhibitor acarbose can interfere with some physiological processes in H. hebetor, although the parasitoid's fitness is not negatively affected. Therefore, enzyme inhibitors may be considered an effective tool for pest control in integrated pest management programs.