Larvicidal activity of seaweeds from northeastern Brazil and of a halogenated sesquiterpene against the dengue mosquito (Aedes aegypti)

Aedes aegypti is considered to be the main vector of a group of arboviruses responsible for dengue and yellow fever. In an attempt to find natural products that could be employed in the effective control of the dengue mosquito, the larvicidal activities of crude extracts obtained from 15 seaweed species collected from northeastern Brazil have been determined. Extracts of Canistrocarpus cervicornis, Laurencia dendroidea, Hypnea musciformis and Chaetomorpha antennina at concentrations of 300 ppm showed ≥50% mortality against fourth instar larvae of A. aegypti. The strongest larvicidal activities (>91% mortality at 50 ppm) were obtained with extracts of L. dendroidea. A halogenated sesquiterpene, identified as elatol, was isolated by sequential fractionation of the n-hexane extract of this species of seaweed, and the isolated compound exhibited potent larvicidal activity with an LC50 value of 10.7 ppm. The isolation of elatol from seaweed could represent an interesting prospect for a novel agent against the dengue mosquito.

► Extracts of seaweeds found in Pernambuco, Brazil, exhibited potent larvicidal effects. ► Red algae, Laurencia dendroidea and Hypnea musciformis, showed the strongest activity. ► The effect against the dengue mosquito, Aedes aegypti, was probably due to elatol. ► L. dendroidea extract did not interfere in the oviposition behavior of the mosquito. ► The brown alga Canistrocarpus cervicornis showed significant larvicidal activity.