Transgenerational combined toxicity effects of neonicotinoids and triazole pesticides at environmentally relevant concentrations on D. magna: From individual to population level

Abstract

The transgenerational impacts of pesticide mixture on Daphnia magna (D. magna) following long-term exposure, particularly regarding transcriptomic effects, remain poorly understood. We analyzed 470 irrigation water samples from various Chinese provinces. Imidacloprid (IMI, 71.1 %), clothianidin (CLO, 60.43 %), and tebuconazole (TEB, 64.68 %) were the most frequently detected pesticides, with nearly 50 % of samples showing mixtures of TEB with IMI or CLO. D. magna were exposed to environmentally relevant concentrations (0.89–1.62 μg/L) over 12 generations. Key effects included reduced fecundity, delayed development, and smaller body size, with these impacts exacerbating across generations. A Leslie matrix model revealed declines in population size, intrinsic rates of increase, and age structure. Notably, mixed pesticide exposures induced specific pathways related to oocyte meiosis, resulting in greater toxicity than single exposures. Additionally, disrupted lipid metabolism and feeding behaviors were linked to insufficient energy for growth and reproduction, affecting ovarian development. These findings highlight the ecological risks of long-term pesticide exposure and offer insights for mitigation strategies in aquatic ecosystems.