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

BACKGROUND Pesticides or plant protection products (PPPs) are risky for spiders in or near agricultural landscapes. However, the risks posed by pesticides to spiders are largely understudied compared with the risks to pollinators. Here, we investigated the distribution of PPPs in adult females, cocoons and webs with prey remnants of Phylloneta impressa. RESULTS Three sample types were collected from the tops of rapeseed on 18 July (before the harvest). Three different ultraperformance liquid chromatograph coupled with triple‐quadrupole tandem mass spectrometer (UHPLC–QqQ–MS/MS) analyses were performed: (i) pesticides and selected metabolites; (ii) quaternary ammonium pesticides (quats); and (iii) pyrethroids. Overall, 23 compounds, 22 pesticides and the metabolite imidacloprid‐urea were detected. The array of pesticides was largest in webs with prey remnants, and according to evaluation via redundancy analysis (RDA), pesticides were similar in spiders and cocoons; however, data inspection revealed differences in pesticide distribution among these samples. Clothianidin was detected in only female spiders, whereas thiamethoxam prevailed in webs with remnants of prey, and acetamiprid, thiacloprid and imidacloprid were found in all three matrices. One of the most abundant compounds was chlormequat, indicating that quats should be considered a possible risk for these spiders. None of the pyrethroids were detected despite being applied in the sampling area, indicating rapid biodegradation. By contrast, some pesticides were detected despite not being applied in the field, indicating that the source of contamination is prey or particles carried by wind and attached to webs. CONCLUSION Overall, the results indicate the different distribution or behavior of several pesticides in the spider matrices. © 2019 Society of Chemical Industry