Larvicidal activity of Persea americana Mill. against Aedes aegypti

To 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.

The 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.

Both 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.

Both 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.