Toxicity of Mexican native plant extracts against larvae of Aedes aegypti (Diptera: Culicidae)

OBJECTIVE: To evaluate five indigenous Mexican plants [Hippocratea excelsa, Hippocratea celastroides, Argemone mexicana (A. mexicana), Tagetes lucida, and Pseudosmodingium perniciosum (P. perniciosum)] toxicity against the fourth instar larvae of the dengue primary vector, Aedes aegypti (A. aegypti). METHODS: Each plant part was treated successively with hexane, ethyl acetate, acetone, and methanol to extract potential active components of the plants against the dengue vector. RESULTS: There was a range of toxicity at 24 or 48 h post-exposure for the different plant parts and organic solvent used (LC₅₀ values ranged between 20 and 890 μg/mL). Extracts from seeds of A. mexicana (hexane washing with methanol and acetone) and stem-bark of P. perniciosum (hexane) showed highest toxicity to Ae. aegypti larvae at 48 h post-exposure (LC₅₀ values were 80, 50, and 20 μg/mL, respectively), thus making them potential candidates as biolarvicides. Efforts are on-going to characterize the bioactive components of the extracts, through chromatography, for their use as biological tools for the control of the primary dengue vector. CONCLUSIONS: A. mexicana and P. perniciosum are good candidates to combat the dengue vector, Ae. aegypti, as they were highly toxic to the larvae.