Effect of the Organophosphorus Pesticide Diazinon on the Reproductive Efficiency of the Freshwater flea Daphnia magna

Abstract

A study was conducted on the chronic toxicity of organophosphorus pesticides, specifically the widely used organophosphorus pesticide Diazinon, on Daphnia magna. This species is a widely used bioindicator and environmental indicator in toxicology for testing chemical toxicity and determining permissible limits for pesticides. Individuals were reared and acclimatized in the laboratory under appropriate conditions. A series of experiments were performed, examining characteristics related to the species' reproductive efficiency, which are key indicators of the presence of toxic substances in the environment (such as time of sexual maturity, number of broods, number of offspring per brood, total number of offspring, and number of parthenogenetic females), under the influence of varying concentrations of Diazinon, ranging from 1 ng/L to 100 ng/L. The experiments continued from 8/1/2025 AD to 8/8/2025 AD. The results showed a decrease in the rate of parthenogenesis and its significant impact through a delay in the time of sexual maturity, a decrease in the number of parthenogenesis broods and the number of individuals resulting from each brood, a decrease in the total number of individuals during the female's lifespan, in addition to a decrease in the number of females that reproduce parthenogenetically, in line with the increase in the concentrations of the Diazinon pesticide used.