Toxicological and biochemical analysis of the
susceptibility of sylvatic Triatoma infestans from the Andean
Valley of Bolivia to organophosphate insecticide |
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Authors: | Pablo Luis Santo-Orihuela Guillermo Carvajal María Inés Picollo Claudia Viviana Vassena |
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Institution: | Centro de Investigaciones en Plagas e Insecticidas, Instituto de Investigaciones Científicas y Técnicas para la Defensa, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina |
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Abstract: | To increase our knowledge of the natural susceptibility of Triatoma
infestans to an organophosphate insecticide, we performed
toxicological and biochemical studies on three sylvatic populations from Bolivia
and two populations from domestic dwellings from Bolivia and Argentina.
Fifty-per-cent lethal doses (LD50) were determined based on the topical
application of fenitrothion on first instar nymphs and mortality was assessed at
24 h. Both type of populations exhibited LD50ratios significantly higher than 1
with a range of the values (1.42-2.47); the maximum value were found in a
sylvatic (-S) population, Veinte de Octubre-S. Samples were biochemically
analysed using a glutathione S-transferase activity assay. The highest
significant activity was obtained for Veinte de Octubre-S and the lowest
activity was obtained for the reference population (102.69 and 54.23 pmol per
minute per mg of protein respectively). Two out of the three sylvatic
populations (Veinte de Octubre-S and Kirus Mayu-S) exhibited significantly
higher glutathione S-transferase activity than that of the reference population.
Based on this analysis of the natural susceptibility of this organism to
organophosphate insecticides, continental and focal surveys of organophosphate
susceptibility should be conducted to evaluate the evolution and distribution of
this phenomenon. |
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Keywords: | sylvatic Triatoma infestans organophosphate insecticide glutathione transferases |
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