tau‐Fluvalinate and other pesticide residues in honey bees before overwintering

Abstract

BACKGROUND Pesticides have often been linked to honey bee colony losses, which occur mainly over winter. In this study, we investigated residues in nine colonies at a model agricultural research site during the period before wintering. Moreover, we applied the acaricide tau‐fluvalinate to the colonies via a strip formulation. The pesticide content was determined by UHPLC‐QqQ‐MS/MS in bees from brood comb initially collected in mid‐September immediately prior to the start of tau‐fluvalinate treatment and 30 later at the time of tau‐fluvalinate strip removal. RESULTS In addition to commonly analyzed pesticides, we detected two plant growth regulators, chlormequat and metazachlor, in the bee colonies. Whereas thiacloprid, chlormequat and acetamiprid decreased after 30 days and contributed considerably to differences between sample time points, other pesticides appeared to be rather stable. Interestingly, we identified diazinon, which has been banned in the European Union since 2007. The residues of methiocarb sulfoxide and imidacloprid‐urea in the absence of their parent compounds indicate historical environmental contamination that can be identified by the detection of residues in a bee colony. tau‐Fluvalinate was detected only after the 30‐day treatment at an average (± SD) concentration of 1.29 ± 1.93 ng/bee, ranging from 0.06 to 7.13 ng/bee. CONCLUSION The multidimensional behavior of pesticides in a bee colony was indicated. Although the research area is used for agriculture, the measured pesticide level was relatively low. The recorded concentrations of tau‐fluvalinate should not be dangerous to bees, as the values were ∼ 200–5000‐fold lower than the reported median lethal dose (LD50) values. © 2019 Society of Chemical Industry

Pesticide comparison of Phylloneta impressa (Araneae: Theridiidae) females, cocoons and webs with prey remnants collected from a rape field before the harvest

“…However, the similar imidacloprid concentrations in females and cocoons may indicate a low metabolism level of imidacloprid. In the previous study, we detected only imidacloprid‐urea metabolites in honeybees, which we suggested to be the result of historical contamination by imidacloprid; in addition, the detection in webs with prey remnants is likely consistent with that suggestion, or the metabolite imidacloprid‐urea could arise from prey metabolization of imidacloprid.…”

“…Thus, these compounds likely originated from the prey. Previously, we also detected these compounds in honeybees in the same area . Here, we show that these plant growth regulators can be found, as in honeybees, in similar amounts to commonly used pesticides in spider matrices.…”

“…Considering the results of our previous study in which we analyzed pesticide residues in honeybees in a nearby apiary in the same year, we found interesting differences in the detection of imidacloprid and clothianidin, which were absent from bees (see Erban et al …”

“…but were detected in the spider matrices in this study. The difference between these two studies can be explained by the different periods of sample collection, since the honeybees were collected in September and October 2017, whereas the matrices of spiders analyzed here were collected earlier, in July 2017. In this study, imidacloprid was detected in all three sample types analyzed, and the concentration (0.7 ng g −1 ) was similar in females and cocoons (detected in all three analyses); webs with prey remnants contained 1.4 ng g −1 (detected in all three analyses).…”

“…In addition, web‐spinning spiders can be affected through their webs acting as collectors of agricultural spray . The possible level of contamination via prey has been documented by the residues found in the bodies of bees that pollinate crops and are contaminated with pesticides . Similar to bees, the number of other target or nontarget insects represents a potential contamination source of pesticides for predators.…”