Larvicidal activity of Persea americana Mill. against Aedes aegypti.

AbstractObjectiveTo evaluate the toxicity of the ethanol and hexane extracts of the different parts of Persea americana Mill. (P. americana) toward third and fourth instars larvae of Aedes aegypti (Ae. aegypti) and to characterize the ethanol extract by qualitative phytochemical analysis.MethodsThe seeds, peels and pulp of P. americana were processed for crude extraction using 95% ethanol and n-hexane. Crude extracts were bio-assayed for larvicidal activity against Ae. aegypti following the World Health Organization standard bioassay method. The mortality was observed at 24 h and 48 h after treatment and data were subjected to probit analysis to determine lethal concentrations (LC50 and LC90). The ethanol extract was characterized by phytochemical analysis.ResultsBoth the hexane and ethanol extracts from the different parts of P. americana exhibited evidence of larvicidal toxicity. The hexane extract from the seeds exhibited the highest toxicity with LC50 and LC90 values of 9.82 mg/L and 22.19 mg/L, respectively, while the ethanol seed extract exhibited LC50 of 16.48 mg/L and LC90 45.77 mg/L, respectively. This was closely followed by the ethanol extract of the peels with an LC50 of 10.35 mg/L and LC90 of 26.29 mg/L. The pulp extracted with ethanol also yielded great larvicidal toxicity with LC50 of 21.32 mg/L and LC90 of 59.45 mg/L. Results of the phytochemical analysis of the ethanol seed extract indicated presence of alkaloids, tannins, saponins, unsaturated steroids and triterpenoids, flavonoids (leucoanthocyanins), fats and oils.ConclusionsBoth the hexane and ethanol extracts of P. americana showed promising potential as an alternative source of a more sustainable, non-toxic and environmentally friendly solution for the control of dengue vector, Ae. aegypti

Ovicidal, larvicidal, and adulticidal activities of <i>Citrus grandis</i> (L.) Osbeck against dengue vector, <i>Aedes aegypti</i> (L.)

252-255Recent studies regarding the harmful effects of synthetic larvicides initiated the need to investigate for unconventional measures that are environmentally-safe and target-specific against Aedes aegypti larvae. Thus, the main objective of the study was to evaluate the ovicidal, larvicidal, and adulticidal toxicity of the hexane extract of Citrus grandis (L.) Osbeckpeels against dengue vector, A. aegypti. Results revealed that the hexane extract of C. grandis peel from Davao exhibited the highest lethal concentration against 3rd and 4th instar larvae with an LC50 and LC90 of 1.11 mg/L and 3.32 mg/L, respectively. Moreover, the knockdown effect of the hexane extract of C. grandis peels on adult female A. aegypti produced 50 % knockdown within 11.50 min and 90 % knockdown within 28.79 min. The test mosquitoes’ mortality was 100 % after 24 h. Lastly, the ovicidal activity of the hexane extract against the eggs of A. aegypti exhibited an LC50 of 13.84 mg/L and LC90 of 25.30 mg/L. The remarkable effects exhibited by C. grandis peels indicate its great potential to be a more sustainable and environmentally-safe plant-based control for the proliferation of the dengue vector, A. aegypti.</i

Ovicidal, larvicidal and adulticidal activity of Citrus grandis L. (Osbeck) against dengue vector, Aedes aegypti (L.)

Recent studies regarding the harmful effects of synthetic larvicides initiated the need to investigate for unconventional measures that are environmentally-safe and target-specific against Aedes aegypti larvae. Thus, the main objectives of the study are to evaluate the ovicidal, larvicidal and adulticidal toxicity of the hexane extract of Citrus grandis peels against dengue vector, A. aegypti. Results revealed that the hexane extract of C. grandis peel from Davao exhibited the highest lethal concentration against 3rd and 4th instars larvae with an LC50 and LC90 of 1.11 mg/L and 3.32 mg/L, respectively. Moreover, the knockdown effect of the hexane extract of C. grandis peels on adult female A. aegypti produced 50% knockdown within 11.50 minutes and 90% knockdown within 28.79 minutes. The test mosquitoes’ mortality was 100% after 24 hours. Lastly, the ovicidal activity of the hexane extract against the eggs of A. aegypti exhibited an LC50 of 13.84 mg/L and LC90 of 25.30 mg/L. The remarkable effects exhibited by C. grandis peels indicate its great potential to be a more sustainable and environmentally-safe plant-based control for the proliferation of the dengue vector, A. aegypti