Acaricide residues in some bee products

Abstract

In Switzerland the acaricides Folbex VA (bromopropylate, BP), Perizin (coumaphos, CM), Apistan (fluvalinate, FV) Bayvarol (flumethrin, FM) are used for varroa control. We studied the contamination level of BP, CM and FV in brood and honey combs, sugar feed and honey after field trials. In samples of recycled pure beeswax and propolis, gathered by beekeepers, we examined the level of all four acaricides. All samples were analysed by gas chromatography with ECD detection. After one normal acaricide treatment in autumn the brood comb was contaminated by BP, CM and FV with residues ranging from 1.8 to 48 mg/kg. The residue level in the honeycomb wax was on average 5 to 10 times lower than in the brood combs. The residues in the combs increased with increasing number (Folbex) or longer duration of treatment (Apistan). The residues in the sugar feed and honey were much lower than in the combs and were all below the Swiss MRL (maximum residue limit). In a laboratory experiment we examined the behaviour of the acaricides during the recycling of old combs into new beeswax. The acaricide concentration in the new recycled wax was on average 1.7 times higher than in old combs under all conditions (longer boiling times or higher temperatures). Since 1991 we have been studying the contamination level of the acaricides in all recycled Swiss beeswax. All commercial samples contain BP, CM and FV in varying amounts. Between the years 1993 and 1996 the residues varied between 2.4 and 4.3 for BP, 0.7 and 1.3 for CM and 1.9 and 2.9 for FV. No flumethrin (FM, a.i. in Bayvarol) above the detection limit of 0.25 mg/kg was found. All but one propolis sample (n = 27) gathered in 1996 contained FV (average 9.80 mg/kg), 10 contained BP (average 1.17 mg/kg) and two of them FM (average 2.54).