Abstract
The use of synthetic insecticides for insect control may lead to different kind of problems, such as vector resistance to insecticides. To avoid these problems, a new research area to study botanical products as possible disease vectors controls, has become a feasible alternative. The purpose of this research was to evaluate the biocide activity of the ethanol extract of seeds of Annona coriacea on Rhodnius neglectus (Chagas disease vector) nymphs and adults. For this, different concentrations extracts were evaluated: 25, 50, 100 and 200mg/ mL, and water in DMSO (20%) was used as control. The experimental design was completely randomized and we conducted the bioassay with nymphs and adults, with 10 nymphs and 10 adults (five males and five females) per treatment. Extract action was evaluated in both bioassays, in order to identify possible effects of mortality and life cycle interruption of nymphs and adults during a 28-day-period. The results obtained showed that the extract of A. coriacea was able to disrupt the development of nymphs and adults of R. neglectus, with a mortality rate of more than 90%, 36% and 100%, at the highest concentrations, respectively. There was also molting inhibition in nymphs, lower reproductive capacity in females, feeding deterrence and morphological changes in nymphs and adults. We concluded that the extract of A. coriacea has insecticide action on nymphs and adults of R. neglectus.
Highlights
Hemathophagy is essential for growing, molting and reproduction of triatomines (Rocha et al 2004, Tartarotti et al 2004)
Effect of A. coriacea different concentration extracts on fourth instar nymphs of R. neglectus: When analyzing the effect of different concentrations on the mortality of the fourth instar nymphs we observed that the effect of the extract of A. coriacea was statistically significant for the different concentrations (p=0.006, GL=4.119)
Effect of concentrations of A. coriacea on fifth instar nymphs of R. neglectus: On the basis of exploratory variations, we found that the number of dead individual specimens showed significant differences in function of the concentrations tested (p=0.028, GL=1.119), the number of dead individual specimens was higher with the increase of extract concentration (Table 1)
Summary
Hemathophagy is essential for growing, molting and reproduction of triatomines (Rocha et al 2004, Tartarotti et al 2004). Due to the negative aspects of excessive use of synthetic insecticides, a new stimulus came up with the phytochemical study of plants, especially those with promising biocide activity and that can represent an alternative to vector control of Chagas disease (Costa et al 2004). Plant species that have been identified as promising in vector control have caused insect mortality, growth inhibition, molting process disruption, deformation of nymphs and adults, reduction in longevity, fertility and fecundity of adults (Schmeda-Hirschmann & Rojas de Arias 1992, Fournet et al 1996, Valladares et al 1999, Bobadilla et al 2005, Coelho et al 2006, Costa et al 2006)
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