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Detection of diptera-specific cry genes in Bacillus thuringiensis strains and effect of solar radiation in toxicity to Aedes aegypti (L.) (Diptera: Culicidae) larvae

Grant number: 10/17967-3
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): January 01, 2011
Effective date (End): December 31, 2011
Field of knowledge:Biological Sciences - Genetics
Principal Investigator:Manoel Victor Franco Lemos
Grantee:Naiara Cristina Pulzi Saito
Home Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The prophylactic control of dengue fever, viral illness transmitted by the Aedes aegypti mosquito, is made by the combat to the vector, mainly through the massive use of synthetic chemicals combat adults and larvae. This fact has led to the emergence of resistant mosquito populations, and may be toxic to other animals and the environment. Thus, we study alternatives to viable disease control, which highlights the use of the entomopathogenic bacterium Bacillus thuringiensis. It produces, during sporulation, crystals biopesticides with protein subunits (Cry) with toxicity, including hemolytic and cytolytic activity, against target insect larvae. For B. thuringiensis var. israelensis, strain with specific lethality in flies, the genes encoding the toxins are cry4A, cry4Ba, cry10Aa, cry11Aa, and cyt1Aa cyt2Ba. The crystals produced, however, can be inactivated by ultraviolet radiation, preventing the application in the field. By PCR, which has great reliability and practicality of application for this purpose, we intend to seek, in isolates of B. thuringiensis of the Laboratory of Genetics of Bacteria and Applied Biotechnology, Faculty of Agriculture and Veterinary Sciences of Jaboticabal, the presence of cyt and cry genes specific to flies, make a selection of strains by PCR-RFLP, and verify the real effectiveness of these in a bioassay with A. aegypti when the solutions are subjected to simulate different intensities of exposure to solar radiation. Thus, new alternatives will be sought to control this vector in the light of the feasibility of application of products based on B. thuringiensis in the field. (AU)