Toxic effects of pesticides with active ingredients cyprodinil, glyphosate isopropylamine salt and indoxacarb on narrow-clawed crayfish (Pontastacus leptodactylus)

In this thesis study, the toxic effects of commercial pesticide formulations with active ingredients cyprodinil, glyphosate isopropylamine salt and indoxacarb on narrow-clawed crayfish (Pontastacus leptodactylus) were investigated. In the first stage, 160 adult narrow-clawed crayfish individuals of both sexes, whose average height and weight were 43.7±0.2 g and 11.0±0.1 cm, respectively, were exposed to different concentrations of pesticides in the 96-hour acute toxicity test, and the LC50 values of the pesticides for this species were calculated by recording the mortalities. In the second stage, 120 adult narrow-clawed crayfish individuals of both sexes, with average weight and length of 45.4±0.3 g and 12.1±0.1 cm, respectively, were subjected to a 96-hour sublethal acute toxicity test (by using 20% of the determined LC50 values) in a 3-replication setup. A control group that was not exposed to any substance was used in both experiments. At the end of the sublethal test, hemolymph and hepatopancreas samples were taken from 3 crayfish per aquarium, a total of 9 crayfish per group, and these samples were used to determine hemolymph biochemical parameters, antioxidant enzyme activities, histopathological changes and genotoxic effect. According to the data obtained, the LC50 values of commercial pesticide formulations with active ingredients cyprodinil, glyphosate isopropylamine salt and indoxacarb were found to be 18.402, 59.715 and 13.133 mg/L, respectively. According to the results of the sublethal toxicology test, it was determined that the pesticide with active ingredient cyprodinil caused oxidative damage, activation of the immune response, suppression of the antioxidant system and severe hepatopancreas damage in narrow-clawed crayfish. While mild hepatopancreas damage was detected in the group exposed to pesticide with active ingredient glyphosate isopropylamine salt, very severe genotoxicity was observed. Finally, it was determined that the pesticide with active ingredient indoxacarb caused oxidative damage and serious histopathology in the hepatopancreas. Obtained LC50 values indicate that the quantitative toxicity of the mentioned pesticides is low in narrow-clawed crayfish. Therefore, the use of these pesticides poses a low risk to natural narrow-clawed crayfish populations as such high concentrations are unlikely to be found in water sources. However, it is still recommended to monitor cyprodinil, glyphosate isopropylamine salt and indoxacarb concentrations in waters where narrow-clawed crayfish inhabits. Moreover, the severe genotoxicity detected in the glyphosate isopropylamine salt group is a remarkable finding. Since DNA has the same structure in all living beings, it is predicted that glyphosate isopropylamine salt exposure may pose a potential danger to humans and other living beings that come into contact with this pesticide. Furthermore, the results obtained in this study revealed the acute toxic effects of these pesticides on narrow-clawed crayfish. Their chronic toxic effects also need to be determined in future studies in order to fill the gap in the toxicology field.