An Examination of Exposure Routes of Fluvalinate to Larval and Adult Honey Bees ( Apis mellifera )

Abstract

Fluvalinate has been extensively used in the United States to combat honey bee colony loss due to Varroa destructor mites. Our objectives were to investigate the extent of fluvalinate contamination in commercially available wax and to define exposure pathways to larval and adult honey bees. All the commercial wax tested contained elevated fluvalinate concentrations, indicating a need for regulation of the sources of wax being rendered for resale. Based on the negative logarithm of the partition coefficient between wax and pollen (–0.54), it is evident that fluvalinate has the potential to actively transfer from the contaminated wax into hive matrices. This was confirmed by adding fluvalinate‐dosed wax, fluvalinate‐impregnated strips, or a combination of the 2 to hives. Larvae and adult bees were checked for fluvalinate exposure using gas chromatography–mass spectrometry analysis. Larvae had detectable concentrations of fluvalinate in all treatments. Bioaccumulation in adult bees was significantly affected by the interaction between treatment type and application time. In other words, residues from hives that only had fluvalinate‐dosed wax were comparable to residues in hives that were actively being treated, suggesting that transfer of fluvalinate from wax into adult bees was an important exposure route. In conclusion, exposure of fluvalinate from contaminated wax and treatment strips to honey bees needs to be considered when the risk for colony loss in hives is being evaluated. Environ Toxicol Chem 2019;38:1356–1363. © 2019 SETAC

Honey bee exposure scenarios to selected residues through contaminated beeswax

“…For each residue detected in beeswax, a transfer rate to each of the hive matrices should have been determined experimentally. To our knowledge, this work has only been done for fluvalinate between wax and pollen by Fulton et al (2019) and for seventeen different pesticides between wax and honey by Shimshoni et al (2019). Fulton et al (2019) have determined a Log K wp value (with 'wp' meaning 'wax/ pollen') of −0.54 for fluvalinate.…”

“…To our knowledge, this work has only been done for fluvalinate between wax and pollen by Fulton et al (2019) and for seventeen different pesticides between wax and honey by Shimshoni et al (2019). Fulton et al (2019) have determined a Log K wp value (with 'wp' meaning 'wax/ pollen') of −0.54 for fluvalinate. It is noteworthy that this value should be compared to 3.85, the Log K ow (=Log P) for fluvalinate.…”

“…Therefore, the Log P value of 7.02 for tau-fluvalinate was used and then standardized. Fulton et al (2019) also concluded that the use of octanol/water partition coefficients to estimate transfer from wax into beebread instead of wax/pollen partition coefficients could lead to an underestimation of the risk to a hive. Shimshoni et al (2019) have determined Log D (=Log distribution ratio, calculated as the logarithmic ratio of pesticide concentration in beeswax to honey at equilibrium) values between wax and honey ranging from −2.06 for thiamethoxam to 2.75 for chlorpyrifos.…”

“…Accumulation of pesticide/veterinary drug residues in beeswax is directly related to their lipophilicity (Johnson et al, 2010;Lozano et al, 2019;Thompson, 2012;Wallner, 1999). From beeswax, part of these residues migrates to the honey bee larva or to the food reserves stored in cells, as demonstrated for fluvalinate between wax and pollen by Fulton et al (2019) and for seventeen different pesticides between wax and honey by Shimshoni et al (2019). Although the larva consists of~80% water (respectively 74.4 ± 0.33% and 79.3 ± 0.19% for larvae and pupae of Apis mellifera ligustica according to Ghosh et al (2016)), it was assumed that the most lipophilic molecules in wax migrate to the larva.…”

Directed evolution of Metarhizium fungus improves its biocontrol efficacy against Varroa mites in honey bee colonies

“…Currently, beekeepers are largely reliant on chemical acaricides to control Varroa despite the dangers that these chemicals pose to bees and the ongoing issues with chemical resistance in the mites. These acaricides have been linked to numerous honey bee health problems, and many studies have shown that residues can accumulate in the hive over time [24][25][26] . Unintended effects on honey bees include increased mortality in brood and adults 27 and an increased susceptibility to pathogens and agrichemicals [28][29][30] .…”