Activity of Essential Oils From Pentanema indicum (L.) Y. Ling and Chromolaena odorata (L.) RMKing & H. Rob Against Three Mosquito Species

Mosquitoes act as biological carriers spreading numerous vector borne diseases globally. The present research aimed to study the effect of essential oils (EOs) from Pentanema indicum (L.) Y. Ling and Chromolaena odorata (L.) R.M. King & H. Rob against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Concentrations of 3.125, 6.25, 12.5 25 and 50 ppm were tested for their mosquitocidal properties. The essential oil (EO) from P. indicum demonstrated promising ovicidal activity, achieving 100% efficacy against Ae. aegypti and Cx. quinquefasciatus and 76% efficacy against An. stephensi at a concentration of 50 ppm within 24 h. Similarly, C. odorata exhibited significant activity at higher concentrations, with ovicidal rates of 72% for Ae. aegypti, 79% for An. stephensi and 64% for Cx. quinquefasciatus at 300 ppm after 72 h. In terms of larvicidal activity, P. indicum showed potent toxicity with LC50 values of 4.28 ppm for Ae. aegypti, 14.01 ppm for An. stephensi and 5.47 ppm for Cx. quinquefasciatus. Additionally, C. odorata exhibited considerable mosquito larvicidal activity at higher concentrations, with LC50 values of 95.28 ppm for Ae. aegypti, 98.95 ppm for An. stephensi and 89.05 ppm for Cx. quinquefasciatus after 24 h. However, no significant pupicidal activity was observed for both EOs. GC-MS analysis identified beta-Pinene (14.31%), D-Limonene (13.48%) and Caryophyllene (25.48%) as the main components in P. indicum. The EO from C. odorata contained alpha-Pinene (12.10%), Geijerene (11.62%) and Caryophyllene (10.64%) as the primary components; probably these compounds were responsible for the observed activities. Toxicity studies indicated that the EOs from both plants had no adverse effects on natural predators. The EOs were then formulated for field application and tested in a laboratory setting; they demonstrated promising mosquitocidal activity without harming natural predators. This study suggests that EOs from P. indicum and C. odorata offer an effective alternative to synthetic pesticides.