Toxicity of Trypsin Endopeptidase Inhibitors to Honey Bees (Hymenoptera: Apidae)

Abstract

Two trypsin endopeptidase inhibitors, bovine pancreatic trypsin inhibitor (BPTI) and soybean trypsin inhibitor (SBTI), which are known to be effective against a range of pest insects, were found to be toxic to adult honey bees ( Apismellifera L.) at 1% wt:vol in sugar solution. Activity of three major midgut endopeptidases of bees (chymotrypsin-like, Nsuccinyl-L-ala-L-ala-L-pro-L-Ieu-p-nitroanilide [SAAPLpNA]-hydrolyzing and trypsin-like) and an exopeptidase, leucine amino peptidase, was measured in bees fed these two inhibitors. In vitro tests using control bee midgut extracts showed that BPTI had high binding affinity for trypsin and less for both chymotrypsin and SAAPLpNA-hydrolyzing activity, and SBTI had high affinity for SAAPLpNA-hydrolyzing activity and trypsin and less affinity for chymotrypsin.