Effects of four protease inhibitors on the survival of worker bumblebees, Bombus terrestris L.

To assess risks posed by transgenic pest-resistant plants, a bumblebee bioa ssay system was developed. Small and large adults of Bombus terrestris were held individually or in groups of 5, 10 or 20 in cages and survival and ra tes of pollen, sugar and water consumption determined. Effects on bee survi val of Kunitz soybean trypsin inhibitor (SBTI), bovine pancreatic trypsin i nhibitor (BPTI) and two potato protease inhibitors, POT-1 and POT-2, were d etermined. SBTI (10 mg.g(-1)) and POT-1 (10 and 5 mg.g(-1)) reduced surviva l significantly. Bees fed POT-2(10 mg.g(-1))had poorer survival than those fed 0.1 or 0.01 mg.g(-1) POT-2. BPTI had no effect. Untreated bee midguts h ad elastase-like (283.0 +/- 16.9 nmol.min(-1).g(-1) gut), chymotrypsin (148 .5 +/- 3.4), trypsin (27.2 +/- 2.8) and leucine aminopeptidase (258.6 +/- 9 .6) activities. Elastase-like and chymotrypsin activities were inhibited by SBTI, POT-1 and POT-2, but not BPTI. Trypsin activity was reduced by each inhibitor. Leucine aminopeptidase activity was unaffected.