Resumo

ROZO, Álvaro; ZAPATA, Cristina  e  BELLO, Felio J.. Evaluation of the toxic effect from Eupatorium microphyllum L.F. (Asteraceae) extracts on Aedes aegypti larvae (Diptera: Culicidae) in laboratory conditions. Rev. Cienc. Salud [online]. 2008, vol.6, n.2, pp.64-73. ISSN 1692-7273.

In the present work the toxic activity of extracts of Eupatorium microphyllum L.F. was evaluated on 4 th instar larvae of the mosquito Aedes aegypti (Linneaus), under laboratory conditions. Aqueous extracts were utilized in concentrations of 500 mg L^-1, 1,500 mg L^-1 and 2,500 mg L^-1 and acetone in concentrations of 10 mg L^-1, 20 mg L^-1, 30 mg L^-1, 40 mg L^-1 and 50 mg L^-1. The bioassays were carried out for triplicate each one with 20 larvae, exposed for 24 hours to 150 mL of solution. In all the bioassays were employed control groups. In the evaluation of the acetone extracts, a negative control was employed to avoid that the mortality of the larvae to occur on account of the solvent. The Aqueous extracts showed low moderate action in the mortality of larvae, less than 20%. On the contrary, the action of the acetone extracts was observed to 10 and 20 mg L^-1 with 15% of mortality, while to 30 and 40 mg L^-1 were registered 22 to 38% of mortality. However, to 50 mg L^-1 the mortality was of 95.4% with highly significant statistical results. The concentrations of the acetone extracts showed to be the most efficient for the control of the mosquitoes selected. Both types of extracts showed toxic effect in larvae of A. aegypti, nevertheless, greater effect in the acetone extracts was observed relating to the aqueous extracts of E. microphyllum, which constitutes a viable alternative in the search of new larvicides from composed natural.

Palavras-chave : Eupatorium microphyllum; Aedes aegypti; bioassays; aqueous and acetone extracts; lethal Concentrations LC₅₀, LC₉₅.