Insecticidal activity of cerrado plant extracts on Rhodnius milesi Carcavallo, Rocha, Galvão & Jurberg (Hemiptera: Reduviidae), under laboratory conditions

Abstract

-Chagas' disease is chiefly transmitted by feces of haematophagous bugs (Triatominae) that ingested Trypanosoma cruzi from blood of infected people or animals. 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. Insecticidal activity of 24 Cerrado plant extracts belonging to five species of four families were assayed on fourth instar nymphs of Rhodnius milesi Carcavallo, Rocha, Galvão & Jurberg (Hemiptera: Reduviidae), under laboratory conditions. 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. Hexanic and ethanolic extracts of Simarouba versicolor, Guarea kunthiana, Guarea guidonia and Talauma ovata caused mortality between 20% and 95% of R. milesi in comparison with the controls, which showed no insect mortality. These preliminary data suggest that the ethanolic extract of the root bark of S. versicolor and the hexanic extract of the root of G. guidonia, responsible for a 95% and 75% insect mortality, respectively, should be chemically investigated and monitored through biological assays in order to determine their insecticidal components, that could be used as a molecular model or as biorational compounds for use in insect control programmes.

Useful Brazilian plants listed in the manuscripts and publications of the Scottish medic and naturalist George Gardner (1812–1849)

“…Spring was antinociceptive (Sá et al, 2012) and Simarouba versicolor A. St.Hil. showed acaricidal and insecticidal activities (Coelho et al, 2006;Valente et al, 2014).…”

Toxicity, repellency and flushing out in Triatoma infestans (Hemiptera: Reduviidae) exposed to the repellents DEET and IR3535

“…Different studies have assessed the behavioral response of Chagas disease vectors to synthetic and natural repellents under laboratory conditions (Alzogaray, Fontán & Zerba, 2000; Coelho, De Paula & Spíndola, 2006; Ferrero, González & Chopa, 2006; Abramson, Aldana & Sulbaran, 2007; Mello et al, 2007; Sfara, Zerba & Alzogaray, 2009; López et al, 2011; Pohlit et al, 2011; Avelar-Freitas et al, 2012; Gomes & Favero, 2013). The effects of DEET were barely explored in T. infestans , and there are no reports on the effects of IR3535 on triatomines.…”

Avaliação de óleos essenciais de plantas aromáticas com atividade inseticida em Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae)

“…Segundo Coelho et al (2006) Huang et al (1999), foram utilizados compostos presentes nos óleos essenciais, o safrol e isossafrol, sendo que os autores constataram que no ensaio de fumigação, apenas 5% da concentração dessas substâncias foram suficientes para provocar a mortalidade de 100% em adultos de S. zeamais. Considerando o desenvolvimento acelerado da resistência dos insetos aos princípios ativos e a variedade de espécies vegetais, acredita-se que o estudo dos óleos essenciais possa desenvolver produtos baseados em protótipos naturais, e desse modo essas substâncias poderiam ser utilizadas como modelos moleculares para novos inseticidas ou recomendados como compostos biorracionais nos programas de controles de triatomíneos.…”