Efeito de extratos de plantas do Cerrado em Dipetalogaster maxima (Uhler) (Hemiptera, Reduviidae)

Abstract

Chagas disease, also known as American Trypanosomiasis, is chiefly transmitted by faeces of haematophagous bugs (Triatominae) that ingested Trypanosoma cruzi from blood of infected people or other mammals. Pyrethroids have been the main insecticides used against these insects. However, some populations of insects have shown significant levels of resistance to several pyrethroids, indicating the need of new insecticides for the control of triatomines. Thus, the insecticidal activity of 83 Cerrado plant extracts belonging to 35 species were assayed on first instar nymphs of Dipetalogaster maxima (Uhler, 1894) (Hemiptera, Reduviidae), species found in Mexico. For the extract application on triatomines, 50 μg of the extract were topically applied in duplicate on dorsal tergites of ten insects. Insects topically treated with acetone, ethanol, as well as insects with no treatment were used as controls. Triatomines were observed over a 28-day period. The extracts showed no insect mortality, however, fruit hexane and stem bark ethanolic extracts of Simarouba versicolor (Simaroubaceae) inhibited the rate of ecdysis in D. maxima (40% and 25%, respectively). These preliminary data suggest that this extracts should be chemically investigated and monitored through biological assays in order to determine the components, so that it may be used as a molecular model or as biorational compounds for use in insect control programmes.