Impact of essential oils on the reproductive biology of Culex quinquefasciatus and their potential in vector control

The rising global health burden of vector-borne diseases transmitted by Culex quinquefasciatus necessitates a shift from conventional synthetic insecticides to sustainable and eco-friendly alternatives. This study investigated the potential of essential oils from Cinnamomum osmophloeum L. and Moringa oleifera Lam. as multifaceted agents for controlling the mosquito's reproductive biology. A series of controlled laboratory bioassays were conducted to evaluate the oils' anti-oviposition, ovicidal, and larvicidal activities. Gravid females were exposed to treated water sources to assess oviposition deterrence, while newly laid egg rafts and first-instar larvae were exposed to varying concentrations to determine mortality rates and sub-lethal effects. The results demonstrated a significant dose-dependent negative impact on the mosquito's life cycle. Both essential oils exhibited potent anti-oviposition activity, significantly reducing the number of egg rafts laid. The ovicidal and larvicidal assays revealed high mortality rates, with C. osmophloeum proving particularly effective, as evidenced by its low LC50 and LC90 values. Furthermore, sub-lethal concentrations of the oils caused developmental abnormalities, including delayed pupation and reduced adult emergence, highlighting their ability to disrupt key physiological pathways beyond simple acute toxicity. The findings suggest that the complex, synergistic chemical composition of these essential oils makes them a durable and sustainable solution for integrated vector management, offering a viable alternative to conventional pesticides that are increasingly compromised by insecticide resistance. This research provides a strong foundation for future field trials to validate their efficacy and support their practical application in vector control programs.