Impact of agricultural pesticides on survival, behavior, and reproductive capacity in Drosophila melanogaster at real-world exposure levels

Pesticides are extensively used in agriculture to enhance crop yield, yet concerns over their long-term effects on human health and ecosystems continue to rise. This study investigates the effects of 11 commonly used pesticides in the Netherlands, i.e. organophosphate-based herbicides (glyphosate, Roundup® Exel), a bipyridyl herbicide (paraquat), SDHI fungicides (fluopyram, boscalid), a dithiocarbamate fungicide (mancozeb), pyrethroid and carbamate insecticides (lambda-cyhalothrin, chlorpropham), phenoxy and thiocarbamate herbicides (MCPA, prosulfocarb), and a dinitroaniline herbicide (pendimethalin), on survival, locomotion, and reproductive capacity in Drosophila melanogaster. Drosophila were continuously exposed from eclosion until natural death for survival and locomotor assays, while reproductive effects were assessed across the full lifespan of the F1 and F2 generation following parental exposure. Drosophila were exposed to individual pesticides or a mix at varying concentrations reflecting the limit of quantification (LOQ), the range of maximum residue limits (MRLs), and higher-concentration exposures beyond MRL levels, with outcomes compared to water- or ethanol-treated controls. The results revealed that several pesticides, including glyphosate, Roundup® Exel and paraquat caused significant, concentration-dependent reductions in survival whereas lambda-cyhalothrin and a mix of pesticides had an acute toxicity at higher concentrations. Additionally, impaired locomotion and behavioral changes were observed following exposure to several pesticides, with glyphosate, paraquat, and lambda-cyhalothrin and mix showing significant effects. A decline in reproductive capacity was also observed, particularly at higher concentrations, with the most notable impacts from paraquat, lambda-cyhalothrin and mix causing a 100 % loss of reproductive capacity compared to controls. The relative toxicity scores and molecular fingerprints showed that molecules resembling organophosphates (glyphosate) and bipyridyls (paraquat) were identified as highly toxic. These compounds significantly impair survival, locomotion, and reproduction abilities. The mix and Roundup® Exel exhibited a synergistic effect, based on their relative toxicity scores in comparison to the individual compounds. These findings suggest that certain pesticides, particularly glyphosate, paraquat, lambda-cyhalothrin, and mix have a considerable impact on survival, behavior, and reproduction, highlighting the need for further research on the long-term implications of pesticide exposure. The implications may extend to insect populations, entire ecosystems, and even human health. This study underscores the importance of evaluating environmental contaminants and their potential effects on life history traits, which could inform public health policies and agricultural practices.