Effect of contamination and adulteration of wax foundations on the brood development of honeybees

Abstract

Various reports recently informed about the effects of contaminated or adulterated wax foundations as a main cause of poor brood and colony development. Beekeepers reported that affected colonies were showing a holey brood pattern and a decline in population size. Twenty-five samples of wax foundations were collected from different sources in Germany. Samples were analyzed using a multi-residue analysis for 147 insecticides, acaricides, and varroacides to investigate the actual load of contamination in beeswax. Furthermore, the effect of selected contaminated and/or adulterated wax foundations on colony and brood development of honeybees was evaluated under field conditions. Our results show that 38 active substances in total were found in the wax samples. Acaricides used in-hive were the most frequently detected contaminants at high concentrations. Trace concentrations of plant protection products and biocides were also found. In the field trials, a significant influence of stearin-adulterated wax on population size, the number of capped brood cells, and termination rate was found compared with the reference. No detectable effects of other treatments on the investigated parameters were observed.Honeybee / Wax foundation / Stearin / Residue / Acaricides

Effect of stearin and paraffin adulteration of beeswax on brood survival

“…The EU Food Fraud Network (2018) does not specify whether scattered brood, which is characteristic in the case of stearin adulteration and has been observed in the present study and other investigations (Alkassab et al 2020;Reybroeck 2017;Reybroeck 2018), is related to the reduced brood survival. It can be assumed that the presence of scattered brood, which is a characteristic effect of stearin adulteration of the wax foundation, is rarely diagnosed correctly in apiaries.…”

“…At present, the problem of wax adulteration has not been sufficiently studied, and preliminary data on the effect of stearin adulteration on the biology of bee colonies have been provided in few studies, only one of which is a peer-reviewed scientific paper, while others are reports (Alkassab et al 2020; Aupinel 2018; EU Food Fraud Network 2018; European Food Safety Authority 2020; Reybroeck 2017; Reybroeck 2018). A drawback of these reports is the lack of a description of statistical analysis methods.…”

Evaluation of pesticide residues in commercial Swiss beeswax collected in 2019 using ultra-high performance liquid chromatographic analysis

“…Coumaphos levels of up to 20 000 μg kg −1 in wax were non-lethal to honey bee larvae, as previously shown in an in vitro model (Kast and Kilchenmann 2022), suggesting that the coumaphos levels currently measured in Swiss beeswax or in wax of the neighbouring countries most likely do not affect brood development. Furthermore, a recent study showed that wax foundations containing coumaphos, taufluvalinate and thymol at a concentration of 10 000 μg•kg −1 each did not increase brood mortality rates (Alkassab et al 2020). Additional studies on lethal and sub-lethal effects of the various pesticides in beeswax as well as the synergistic effects of a mix of pesticides on honeybees would be helpful to determine maximal residue levels for beeswax.…”

Adulteration of beeswax: A first nationwide survey from Belgium

“…Beeswax adulteration is an emerging issue and could be a challenge for bee health, as recently shown for stearin, and palmitin [ 30 , 41 ] and possibly for human health too, due to the potential presence of hazardous substances in unrefined paraffin of fossil origin that could be used as adulterant. Carcinogenic compounds such as polyaromatic hydrocarbons (PAHs) are known to be present at substantial concentrations (up to 1%) in unrefined waxes originating from various crude oils [ 42 ].…”