TOXICITY OF TRYPSIN ENDOPEPTIDASE INHIBITORS TO HONEY-BEES (HYMENOPTERA, APIDAE)

Two trypsin endopeptidase inhibitors, bovine pancreatic trypsin inhibi tor (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 (Apis mellifera L.) at 1% wt:vol in sugar solution. A ctivity of three major midgut endopeptidases of bees (chymotrypsin-lik e, N-succinyl-L-ala-L-ala-L-pro-L-leu-p-nitroanilide [SAAPLpNA]-hydrol yzing and trypsin-like) and an exopeptidase, leucine amino peptidase, was measured in bees fed these two inhibitors. In vitro tests using co ntrol bee midgut extracts showed that BPTI had high binding affinity f or trypsin and less for both chymotrypsin and SAAPLpNA-hydrolyzing act ivity, and SBTI had high affinity for SAAPLpNA-hydrolyzing activity an d trypsin and less affinity for chymotryposin.