The influence of sublethal doses of imidacloprid on protein content and proteolytic activity in honey bees ( Apis mellifera L.)

Abstract

The effect of sublethal doses of imidacloprid on protein content and activity of proteases on honey bees was analyzed. The study was conducted in three experimental groups: colonies from groups BE-5 and BE-200 were contaminated with 5 and 200 ppb of imidacloprid, respectively, via their food supply (syrup and pollen), while group BE was used as control (untreated). Bee samples were collected 3 and 10 weeks after feeding started. Protein concentration in bee tissue extracts was analyzed with reference: (a) to the dose of imidacloprid; and (b) duration of exposure to the chemical. The average quantity of protein content was significantly higher at the 3-week interval than in the 10-week interval and the bees from control colonies (BE) had significantly higher protein contents than contaminated bees (BE-5 and BE-200), even 3 weeks after feeding with imidacloprid started. Similarly, the activity of proteolytic enzymes (proteases) was found to be dependent on the dose of imidacloprid used, compared to bees from control colonies showing significantly higher activity.