Abstract
Clothianidin is a neonicotinoid insecticide commonly employed in agricultural fields to kill or repel pests. Nonetheless, unintentional chronic exposure to this chemical may adversely affect reproductive fitness in non-target organisms. Hence, to understand the reproductive risks of clothianidin exposure, the present study was conducted to explore the chronic sub-lethal effects of clothianidin on the reproductive health of Drosophila melanogaster. Briefly, the first instar larvae of D. melanogaster were exposed to six sublethal concentrations (0.05-0.1 µg/mL) of clothianidin till their adult stage. Notably, clothianidin exposure (0.07 µg/mL) reduced fecundity and egg hatchability by 42.57 % and 10.93 %, respectively, in treated females. The test chemical also escalated subcellular ROS production by upregulating catalase, superoxide dismutase, and reduced glutathione levels. Moreover, oxidative damage to proteins and lipids was also evident. Tissue injuries were apparent in the gonads of both sexes. The investigation was extended to the subcellular level, where chronic exposure to clothianidin reduced glucose 6-phosphate dehydrogenase (G6PD), angiotensin-converting enzyme (AnCE), and vitellogenin activities in adult males by 53.65 %, 52.54 %, and 43.44 %, respectively, at 0.1 µg/mL concentration. Likewise, in females, G6PD, AnCE, and vitellogenin activities were decreased by 52.63 %, 39.55 %, and 36.06 %, respectively. Additionally, mitoferrin and malate dehydrogenase activities were downregulated by 38.12 % and 53.44 % at 0.1 µg/mL concentration. Hence, the findings of this study equivocally suggest that exposure to clothianidin at sub-lethal concentrations fuels oxidative stress and modulates reproductive mediators in D. melanogaster. Moreover, nuclear damage and tissue injuries in gonads can synergistically contribute to less fecundity and fertility in D. melanogaster.
