Efficacy of Chenopodium ambrosioides essential oil against Anopheles gambiae sensu lato, Anopheles funestus, and Aedes aegypti mosquitoes in Muheza, Tanzania

Abstract

Introduction: Vector-borne diseases continue to place a heavy burden on millions of people across the globe, causing more than 700,000 deaths annually. Insecticide resistance among mosquito populations poses a critical challenge to vector control efforts in sub-Saharan Africa, necessitating the alternative mosquito vector control tools. This study aimed to determine the efficacy of Chenopodium ambrosioides essential oil against Anopheles gambiae sensu lato, Anopheles funestus, and Aedes aegypti which are primary vectors of diseases.

Methods: Insecticide susceptibility bioassays were conducted according to the World Health Organization guidelines on 2–5-day-old mosquitoes. Three mosquito species were exposed to C. ambrosioides essential oil (10%), Lambdacyhalothrin (0.05%), Permethrin (0.75%) and Deltamethrin (0.05%) (pyrethroids) and Dichlorodiphenyltrichloroethane (DDT) (4%) insecticides. Mortality rates were recorded 24 hours post-exposure, and knockdown times (KDT50 and KDT95) were calculated to assess efficacy of insecticides.

Results: All mosquito species were susceptible to C. ambrosioides essential oil (10%), with mortality rates above 95% after 24 hours. An. gambiae s. l. showed possible resistance to Permethrin (0.75%) and Deltamethrin (0.05%) with mortality rates of 93% and 92%, respectively. An. gambiae s. l. was resistant to Lambdacyhalothrin (0.05%), showing a 57% mortality rate. An. funestus was susceptible to all tested insecticides, while Ae. aegypti was susceptibility to all insecticide tested except to DDT (4%). All insecticides achieved a knockdown rate of 50% (KDT50) within 1 hour across all species. However, C. ambrosioides essential oil demonstrated the shortest mean knockdown time for KDT50, ranging from 11.4 to 13.1 minutes.

Conclusion: C. ambrosioides essential oil displayed strong insecticidal activity, with faster knockdown times than conventional insecticides. These findings suggesting that, C. ambrosioides extracts is a potential alternative vector control product against malaria and arbovirus vectors. Further studies are warranted to explore the long-lasting effects of C. ambrosioides essential oil formulations to develop novel mosquito control product.