Toxicity of Acalypha indica (Euphorbiaceae) and Achyranthes aspera (Amaranthaceae) leaf extracts to Aedes aegypti (Diptera: Culicidae)

Alternative control strategies for the dengue vector Aedes aegypti L. (Diptera: Culicidae) include botanical insecticides. They are believed to pose little threat to the environment or to human health and may provide practical substitutes for synthetic insecticides. In this study, we determined the biological activities of methanol extracts of Acalypha indica L. (Euphorbiaceae) and Achyranthes aspera L (Amaranthaceae) leaves individually and in combination as botanical insecticides against Ae. aegypti. Based on LC 50 values for 4th instar Ae. aegypti, the combined extracts showed the strongest larvicidal activity (277 ppm). A. aspera and A. indica extracts individually gave similar results (409 and 420 ppm, respectively). Respective LC 50 values for pupae were 326 ppm, 456 ppm, and 467 ppm. In studies of smoke toxicity, 64% of females exposed to negative control smoke (no extract) blood fed on chicken, whereas 17% blood fed when exposed to smoke containing A. aspera extract and to positive control smoke (0.2% d-allethrin). In the field, treatment of water storage tanks (≈ 0.5 m 3) with combined plant extract reduced larval and pupal populations by 97% and 81%, respectively, after 5 days. Given the results of this study, further evaluation of the combined ( A. indica + A. aspera) extract as a mosquito larvicide is warranted. Mosquito coils with A. aspera extract also show promise as a practical and potentially economical means for mitigating mosquito blood feeding. The picture shows the Medicinal Plant of Acalypha indica and Achyranthes aspera for the control of dengue vector, Aedes aegypti . Results of this study, further evaluation of the combined ( A. indica + A. aspera) extract as a mosquito larvicide is warranted. Mosquito coils with A. aspera extract also show promise as a practical and potentially economical means for mitigating mosquito blood feeding. [Display omitted] ► Our study indicates that further evaluation of the combined A. indica + A. aspera extract as a mosquito larvicide is warranted. ► Mosquito coils with A. aspera extract also show promise as a practical and economical means for mitigating mosquito blood feeding. ► Given the eventuality of further development of these phytochemicals, particular attention should be given to plant culture and nutrition conditions, the use of bioassay-guided fractionation to isolate and identify the most active phytochemical constituents, and, in the case of mosquito larvae, the potential for combining bo