Effect of Aqueous Extract of Protium heptaphyllum (Burseraceae) on Lutzomyia longipalpis (Diptera: Psychodidae), a Proven Vector of Visceral Leishmaniasis in Brazil

Abstract

Objective: To evaluate the toxicity of aqueous extract of Protium heptaphyllum on Lutzomyia longipalpis a proven vector of visceral leishmaniasis (VL). Methods: Aqueous extract of the leaves of P. heptaphyllum were prepared at 0.25, 0.10,0.05 and 0.025 mg/mL concentrations, and 100 μL was applied to adults of Lu. longipalpis (n=20). Controls included 20 adults that were treated with 100 μL distilled water (negative control) and 20 adults that were treated with 100 μL alpha-cypermethrin at 196 µg/mL concentration (positive control). The percentage of dead insects in each group was observed at 1, 2, 4, 8, 12, 24, 48 and 72h after application. Results: The mortality rate of Lu. longipalpis after 2h of exposure to the extract at a concentration of 0.1 mg/mL was 52%, behaving similarly to the positive controls (cypermethrin), and the extract at a concentration of 0.25 mg/ml was able to kill 56% of insects within the first hour of exposure. After 72h, the aqueous extract of P. heptaphyllum showed a mortality rate of about 81% and 83%, at concentrations of 0.1 and 0.25 mg/mL, respectively. Conclusion: The extract of P. heptaphyllum contains terpenes, a molecule with recognized toxicity in insects, and which may be responsible for killing the phlebotomines. These results demonstrate the potential use of this extract in the control of this vector