Impact of a perfluorinated organic compound PFOS on the terrestrial pollinator Bombus terrestris (Insecta, Hymenoptera)

Abstract

Perfluorinated organic chemicals like perfluorooctane sulfonic acid (PFOS) are persistent environmental pollutants that have been measured in a great diversity of wildlife worldwide, especially in the aquatic compartment. However, little information is available on the presence and effects of PFOS in the terrestrial compartment. Therefore, we investigated in this project the risks for effects, bioaccumulation and potential mechanisms of activity of PFOS in the bumblebee Bombus terrestris L. (Hymenoptera: Apidae) that is an important worldwide pollinator in the terrestrial compartment of wildflowers and cultivated crops. The exposure to PFOS occurred orally via the drinking of treated sugar water in a wide range from 1 μg/l up to 10 mg/l, containing environmentally relevant as well as high concentrations, and this was done with use of microcolonies of B. terrestris in the laboratory. A chronic toxicity assay demonstrated high bumblebee worker mortality (up to 100%) with an LC(50) of 1.01 mg/l (R(2) = 0.98). In addition, PFOS posed strong detrimental reproductive effects, and these concerted with a dramatic reduction in ovarian size. HPLC-MS demonstrated a bioaccumulation factor of 27.9 for PFOS in bumblebee workers fed with sugar water containing 100 μg/l PFOS during 5 weeks (2184 ± 365 ng/g BW). Finally, potential mechanisms of activity were investigated to explain the significant impact of PFOS on survival and reproduction capacity of B. terrestris. Exposure of bumblebee workers to PFOS resulted in a significant decrease in mitochondrial electron transport activity (p = 0.035) and lipid amounts (p = 0.019), while the respective p-values were 0.58 and 0.12 for protein and glucose amounts. Hence, addition of PFOS to ecdysteroid responsive Drosophila melanogaster S2 cells resulted in a strong antagonistic action on the EcR-b.act.luc reporter construct, demonstrating that PFOS may exert its effects partially through an endocrine disrupting action via the insect molting hormone or ecdysteroid receptor.

Effects of ‘inactive’ ingredients on bees

“…These dissimilarities in topical toxicities may reflect intrinsic differences in species susceptibility, but distinguishing this from a more direct role of the other formulation ingredients in enhancing neonicotinoid penetration of the bee cuticles will require further testing. Bumble bees are highly susceptible to 1 ppm of a strong surfactant perfluorooctylsulfonic acid [34]. Clearly, hazards of agrochemicals to pollinators cannot be predicted if technical ingredients are tested alone without the formulation ingredients and if tested only on a single species.…”

Thyroid disruption effects of environmental level perfluorooctane sulfonates (PFOS) in Xenopus laevis

“…There were reports that PFOS exposure induced THs deficiency (Yu et al 2009a(Yu et al , 2010 and THs alteration (Yu et al 2009b;Curran et al 2008) in rats, and alteration of thyroid homeostasis in mice (Fair et al 2011;Fuentes et al 2006). PFOS may exert its effects in the bumblebee partially through an endocrine disrupting action via the insect molting hormone or ecdysteroid receptor (Mommaerts et al 2011). For fish, PFOS exposure caused reproductive and developmental toxicity in fathead minnows (Ankley et al 2005), altered gene expressions in the hypothalamicpituitary-thyroid (HPT) axis related to early thyroid differentiation in Zebrafish embryos , and resulted in a trend of increased triiodothyronine (T3) levels with no statistical significance in Zebrafish embryos/ larvae (Du et al 2009).…”

Chronic oral lethal and sub‐lethal toxicities of different binary mixtures of pesticides and contaminants in bees (Apis mellifera, Osmia bicornis and Bombus terrestris)

“…General considerations: The chemical toxicity test regimes for other species of euscocial bees are less well established and are not captured by standard OECD protocols. However, the use of queenless microcolonies for bumblebees has been established and used for a range of studies including assessing the toxic effects of GM crops (Mommaerts et al 2011;Laycock et al 2012;Laycock et al 2014). The basic method has been described by Regali and Rasmont (1995) and Tasei et al (2000) and is also specifically recommended by EFSA PPR Panel (2012).…”