Combinations of plant essential oils and their major compositions inducing mortality and morphological abnormality of and .

Extensive uses of synthetic insecticides to control mosquito's populations have induced the insects to develop resistance against them, rendering them ineffective today. Moreover, they cause serious impacts on human health and the ecosystem. Therefore, safe and effective natural alternatives are needed. This study evaluated the larvicidal and pupicidal activities of essential oils (EOs) from and and the major constituents against and mosquitoes as well as recorded their morphological aberrations at death. The GC-MS analysis showed that trans-anethole was the major constituent of EO, and limonene was the major constituent of . EO. Both were more effective against the larvae and pupae of . than those of . . A 2.5% . EO + 2.5% trans-anethole combination showed the highest larvicidal and pupicidal effects against . and . with an LT ranging from 0.2-6.9 h. Between the two tested constituents, trans-anethole exhibited stronger larvicidal and pupicidal activities (LC ranging 2.4-3.4%) against the two tested mosquito species than d-limonene (LC ranging 2.5-3.7%). Most importantly, 5% trans-anethole, 5% d-limonene, and 2.5% . EO + 2.5% trans-anethole were more effective (LT ranging 0.1-0.3 h) than 1% (w/w) temephos (LT ranging 2.9-3.1 h). Morphological aberrations at death observed were such as color pigment and thorax shape abnormalities. To conclude, trans-anethole, d-limonene, and a combination of EO + trans-anethole, are natural compounds that not only are as effective as temephos at the time of this study, but should be also be much safer to human health.