Effects on detoxification enzymes in different life stages of honey bees (Apis mellifera L., Hymenoptera : Apidae) treated with a synthetic pyrethroid (flumethrin)

The activities of two detoxification enzymes, glutathione S-transferase (GS T) with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate, and glutathione pe roxidase with tert-butyl hydroperoxide as substrate (GSH-Px[TBH]), were mea sured in the larvae, pupae and adults of honey bees (Apis mellifera ligusti ca Spinola) originating from two colonies, one untreated acting as a contro l group and the other treated with flumethrin. The treatment with flumethri n led to increased GST activity in the larval instars, pupae and nurse bees compared with the control group. In particular, the late fifth larval inst ars (LS) and the pupal instars showed increased GST activities. GSH-Px[TBH] activities were highest in the early larval instars (L1-L2). Treatment wit h flumethrin resulted in the induction of GSH-Px[TBH] activity in the L4-L5 instars and LS. In the forager bees, the enzyme activity was lower in the group treated with flumethrin than in the control group. This could have be en due to unknown extrinsic environmental factors. In general, the average protein contents were lower in the flumethrin-treated group than in the con trol group. In the LS and pupal stage, and in the adult worker bees, the di fferences were significantly lower. This inhibition of growth could be due to metabolic costs resulting from exposure to toxicants.