Toxicity of Coumaphos Residues in Beeswax Foundation to the Honey Bee Brood

Abstract

Coumaphos is one of the most frequently detected pesticides in recycled beeswax. The objective was to assess the maximal level of coumaphos in foundation sheets that could exist without lethal effects on the honey bee larvae. Brood development was followed in cells drawn on foundation squares containing coumaphos ranging from 0 to 132 mg/kg. Furthermore, larval exposure was determined by measuring the coumaphos level in the drawn cells. Coumaphos levels in the initial foundation sheets up to 62 mg/kg did not increase brood mortality because the emergence rates of bees raised on these foundation squares were similar to controls (median of 51%). After a single brood cycle, coumaphos levels in the drawn cells were up to three times lower than the initial levels in foundation sheets. Hence, coumaphos levels of 62 mg/kg in the initial foundation sheets, almost the highest exposures, resulted in levels of 21 mg/kg in drawn cells. A significantly reduced emergence rate (median of 14%) was observed for bees raised on foundation sheets with initial coumaphos levels of 132 mg/kg, indicating increased brood mortality. Such levels resulted in coumaphos concentrations of 51 mg/kg in drawn cells, which is close to the median lethal concentration (LC50) as determined in previous in vitro experiments. In conclusion, brood mortality was increased on wax foundation sheets with initial coumaphos levels of 132 mg/kg, while no elevated mortality was observed for levels up to 62 mg/kg. Environ Toxicol Chem 2023;42:1816–1822. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Do Varroa destructor (Acari: Varroidae) mite flows between Apis mellifera (Hymenoptera: Apidae) colonies bias colony infestation evaluation for resistance selection?

“…However, such treatments are costly and are not always consistently implemented by beekeepers ( Hernandez et al 2022 ). In addition, they can contaminate bee products by leaving residues ( Bogdanov 2006 , Kast et al 2019 ), have side effects on honey bees ( Higes et al 1999 , Colin et al 2020 , Kast et al 2023 ) and lead to the emergence of mite resistance ( Elzen et al 2000 , Spreafico et al 2001 , Hernández-Rodríguez et al 2021 ). Therefore, since the global invasion of V. destructor , alternative approaches favoring long-term colony survival, without the need for such treatments have been explored ( Dietemann et al 2012 ).…”