Synergistic Effect of Bioactive Monoterpenes against the Mosquito, Culex pipiens (Diptera: Culicidae)

Abstract

Mosquitoes represent one of the most important vectors and are responsible for the transmission of many arboviruses that affect human and animal health. The chemical method using synthetic insecticides disturbs the environmental system and promotes the appearance of resistant insect species. Therefore, this study investigated the insecticidal effect of some binary monoterpene combinations (1,8 cineole + α-pinene and carvone + R (+)-pulegone) using a mixture design approach. The fumigant toxicity was evaluated against Culex pipiens female adults using glass jars. The results show that the toxicity varies according to the proportions of each compound. Indeed, Mixture 1 (1,8-cineole + α-pinene) displayed a strong toxic effect (51.00 ± 0.86% after 24 h and 100.00 ± 0.70% after 48 h) when the pure compounds were tested at 0.25/0.75 proportions of 1,8-cineole and α-pinene, respectively. Nevertheless, the equal proportion (0.5/0.5) of carvone and R (+)-pulegone in Mixture 2 exhibited a toxic effect of 54.35 ± 0.75% after 24 h and 89.96 ± 0.14% after 48 h, respectively. For Mixture 1, the maximum area of mortality that the proposed model indicated was obtained between 0/1 and 0.25/0.75, while the maximum area of mortality in the case of Mixture 2 was obtained between 0.25/0.75 and 0.75/0.25. Moreover, the maximum possible values of mortality that could be achieved by the validated model were found to be 51.44% (after 24 h) and 100.24% (after 48 h) for Mixture 1 and 54.67% (after 24 h) and 89.99% (after 48 h) for Mixture 2. It can be said that all purev molecules tested through the binary mixtures acted together, which enhanced the insecticide’s effectiveness. These findings are very promising, as the chemical insecticide (deltamethrin) killed only 19.29 ± 0.01% and 34.05 ± 1.01% of the female adults after 24 h and 48 h, respectively. Thus, the findings of our research could help with the development of botanical insecticides that might contribute to management programs for controlling vectors of important diseases.

Larvicidal Activity of Hemp Extracts and Cannabidiol against the Yellow Fever Mosquito Aedes aegypti

“…albopictus, and Ae. aegypti [31][32][33][34][35]43]. In addition, we demonstrated that hemp leaf extracts exhibited similar toxic potency against a PR strain of Ae.…”

“…Hemp also produces over 100 terpenes, more than 40 noncannabinoid phenolics, and more than 30 flavonoids [22,28]. Notably, the terpenes linalool, eucalyptol, p-cymene, and thymol have shown larvicidal and/or adulticidal activity to various mosquitoes species [29][30][31]. Thus, the hemp plant produces a variety of secondary metabolites with potential for mosquito control.…”

Larvicidal Potency of Some Selected Nigerian Plants against Aedes aegypti

“…The available research shows that the potential larvicidal effects of several plants on mosquito vector behavior and reproductive fitness have not been thoroughly studied. It has been demonstrated that these secondary metabolites are effective against both the larvae and adults of numerous mosquito species [23,24]. Therefore, this study aimed at developing larvicidal activities with a certain number of Nigerian plant extracts against larvae of Ae.…”