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J. Venom. Anim. Toxins incl. Trop. Dis.

V.20, 2014.

Original paper - ISSN 1678-9199.

 

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

 
Frances TT Trindade1 2, Ângela A Soares3, Andréa A de Moura3, Tiago B Rego3, Andreimar M Soares3, Rodrigo G Stábeli2 3, Leonardo A Calderon2 3, Alexandre de Almeida e Silva1 2*

 

1Laboratory of Insect Bioecology, Department of Biology, Federal University of Rondônia (UNIR), Porto Velho, Rondônia State, Brazil

2Oswaldo Cruz Foundation – Rondônia (Fiocruz – Rondônia), Porto Velho, Rondônia State, Brazil

3Center for the Study of Biomolecules Applicable to Health, Oswaldo Cruz Foundation – Rondônia, and Department of Medicine, Federal University of Rondônia (UNIR), Porto Velho, Rondônia State, Brazil.

 

ABSTRACT

Background

Mosquitoes 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.

 

Methods

The 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.

 

Results

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. 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).

 

Conclusions

The 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.

 

Key words: Vector control; Anuran amphibians; Dengue; Malaria

 

Received: January 6, 2014; Accepted: June 24, 2014; Revised: July 2, 2014

 

Corresponding author: Alexandre de A e Silva alealsil@unir.br

 

Competing interests

The authors declare that there are no competing interests.

 

Authors’ contributions

FTTT and AAS conceived this study, designed the experiments and analyzed data. ÂAS, AAM, TBR, AMS, RGS and LAC contributed to animal material collection and crude venom analysis. All authors contributed equally to the writing and revision of the article. All authors read and approved the final manuscript.

 

Ethics committee approval

The present study was approved by the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA 17983-1, 27131-2, 27131-3) and Council for the Management of Genetic Resources (CGEN 010627/2011-1).