Insecticidal activity of Leptodactylus knudseni and Phyllomedusa vaillantii crude skin secretions against the mosquitoes Anopheles darlingi and Aedes aegypti

Abstract

BackgroundMosquitoes are important vectors of several diseases, including malaria and dengue, and control measures are mostly performed using chemical insecticides. Unfortunately, mosquito resistance to commonly applied insecticides is widespread. Therefore, a prospection for new molecules with insecticidal activity based on Amazon biodiversity using the anurans Leptodactylus knudseni and Phyllomedusa vaillantii was performed against the mosquito species Anopheles darlingi and Aedes aegypti.MethodsThe granular secretion from anuran skin was obtained by manual stimulation, and lethal concentrations (LCs) for larvicidal and adulticidal tests were calculated using concentrations from 1-100 ppm. The skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species.ResultsThe skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species. The calculated LC50 of L. knudseni skin secretions against An. darlingi was 0.15 and 0.2 ppm for adults and larvae, respectively, but much higher for Ae. aegypti, i.e., 19 and 38 ppm, respectively. Interestingly, the calculated LCs50 of P. vaillantii against both mosquito species in adults were similar, 1.8 and 2.1 ppm, respectively, but the LC50 for An. darlingi larvae was much lower (0.4 ppm) than for Ae aegypti (2.1 ppm).ConclusionsThe present experiments indicate that skin secretions from L. knudseni and P. vaillantii contain bioactive molecules with potent insecticide activity. The isolation and characterization of skin secretions components will provide new insights for potential insecticidal molecules.

Larvicidal activity of natural and modified triterpenoids against Aedes aegypti (Diptera: Culicidae)

“…aegypti. 26,27 The larvicidal effects of the derivatives from BA and UA in the present study resulted mostly in a reduction in their activity, i.e. increased LC values.…”

“…Interestingly, another anopheline, Anopheles darlingi , was generally more susceptible to insecticidal compounds, both from animal sources, than the culicine Ae. aegypti …”

Skin secretions of Leptodactylidae (Anura) and their potential applications

“…Consequently, schooling follows attending females through the ponds [ 110 , 112 ]. Waves presumably transfer chemical signals that the tadpoles identify to follow attending females and to encourage tadpole schooling behavior [ 112 , 113 ]. Inside the parental care context, the chemical signals and the biological mechanism remained unknown.…”