Alguns fitoquÃmicos apresentam compostos tóxicos que podem ser explorados no controle de larvas de
mosquitos. Sendo assim, o efeito larvicida de extratos aquosos a 0,05% (peso:volume) de 14 plantas medicinais
foram avaliadas para o controle de larvas de Aedes aegypti (L.) no México. Os bioensaios foram conduzidos com
larvas nos estágios iniciais do quarto instar mediante a submersão das larvas nos extratos. Resultados preliminares
com as plantas testadas mostraram que a maior mortalidade foi observada com extratos de macerados e de plantas
inteiras. As mortalidades médias obtidas para Solanum nigrescens Martens & Galeotti, Operculina pteripes (G.Don)
O'Donell e Phoradendron tamaulipensis Trel. foram 55; 17,5 e 5,8% respectivamente. Posteriormente, foram
realizadas bioensaios com plantas de S. nigrescens coletadas mensalmente no campo para avaliar o efeito sazonal na
atividade larvicida com diferentes partes da planta. Somente extratos obtidos das raÃzes maceradas (mortalidade de
83 a 100%) ou inteiras (mortalidade de 88 a 98%) foram letais às larvas de A. aegypti. As mortalidades mensais
médias obtidas com extratos de raÃzes maceradas ou inteiras de S. nigrescens foram 91,6 e 93,3% respectivamente.
Some phytochemicals comprise toxic compounds that can be exploited in the control of mosquito
larvae. Therefore, larvicidal effect of aqueous extracts of 14 medicinal plants at 0.05% (weight: volume) was
evaluated against Aedes aegypti (L.) in Mexico. Bioassays were conducted with early fourth instars submerged in
plant infusions to ingest the potential insecticide compounds. A preliminary bioassay for all plants showed that the
highest mortality occurred in extracts from crushed and whole plants. The mean mortality for Solanum nigrescens
Martens & Galeotti, Operculina pteripes (G.Don) O'Donell and Phoradendron tamaulipensis Trel. was 55, 17.5 and
5.8% respectively. Then, monthly bioassays with fresh field-collected S. nigrescens were conducted to evaluate
seasonal variation in larvicidal activity with different plant parts. Only extracts of crushed (83-100% mortality) and
entire (88 – 98% mortality) root were lethal to A. aegypti larvae. Monthly average mortality was 91.6 and 93.3% for
crushed and whole root extracts of S. nigrescens. These findings can be exploited to developed ecologically friendly
products to be integrated with other control tactics in dengue vector control program in Mexico.
