A novel pyrazole–pyridine derivative (PPD) targets specific biological pathways in the larval stages of the northern house mosquito Culex pipiens Linnaeus (Diptera: Culicidae)

Abstract Background Mosquitoes cause a variety of health problems in humans and pets. So, the control of mosquito larvae is one of the best ways to avoid health problems arising from diseases transmitted by these insects. There are various control mechanisms including mechanical, biological and chemical control. The latter, despite the presence of some obstacles associated with its use, is preferred because of its ability to supply rapid management results. Result A novel laboratory-synthesized chemical compound containing pyrazole and pyridine moieties (pyrazole–pyridine derivatives, PPD) was used to control and address the biological effects on Culex pipiens mosquito second larval instar. A sublethal concentration (LC30) of PPD inhibited larval growth by about 50%. Furthermore, the developmental time of larvae into pupae and the emergence of adults from the pupal stages were increased by about 20% and 17%, respectively. The ultrastructural studies on the midgut cells revealed that treated larvae suffered dramatic degeneration in the gastric caeca and the posterior midgut cells, while the anterior midgut epithelium appeared with an abundance of lysosomal activities. Additionally, treated larvae showed fluctuated activities in the levels of the detoxifying enzymes and increased levels in total antioxidants. Conclusions These results clearly show that pyrazole and pyridine moieties containing compounds can be used against larval stages of C. pipiens.