Lethal effect of a bait for Rhodnius prolixus (Hemiptera: Reduviidae), the vector of Chagas' disease, containing hexachlorocyclohexane (HCH), under laboratory conditions

Abstract

The lethal effect of a bait containing an aqueous hexachlorocyclohexane (HCH) suspension at the concentration of 1g/l and maintained at room temperature was studied in the laboratory over a period of 12 weeks. The suspension was placed in a latex bag hanging inside a 1000-ml beaker tightly covered with nylon netting, and left there with no changes for 85 days. Sixteen groups of R. prolixas bugs, consisting on average of 30 specimens each, were successively exposed to the bait and observed at different intervals for one week each. The mortality rate was 100% for all groups, except for the 16th, whose mortality rate was 96.7%. As the groups succeeded one another, mortality started to occur more rapidly and was more marked at the 6- and 24-h intervals. Later tests respectively started at 6:00 a.m. and 6:00 p.m. showed that diurnal and nocturnal periodicity in the offer of food had no effect on mortality. First- and 2nd- instar nymphs and adults male were more sensitive and 5th- instar nymphs were more resistant to the active principle of the bait.

Biocide activity of <i>Annona coriacea</i> seeds extract on <i>Rhodnius neglectus</i> (Hemiptera: Reduviidae)

“…The results obtained with adult mortality of R. neglectus were similar to those obtained by Lima et al (1992), with aquatic suspension of hexachlorocyclohexane (HCH), registering 100% of mortality for the adult insects and fifth instar nymphs. We observed that fifth instar nymphs were more resistant to the insecticide and died only after exposure for several days.…”

Desenvolvimento de Rhodnius pictipes Stal, 1872 alimentado através de membrana de silicone e em camundongos (Hemiptera, Reduviidae, Triatominae)

“…A alimentação artificial supre as necessidades nutricionais desses insetos, sem os inconvenientes da manutenção de hospedeiros vivos, além de minimizar efeitos de características individuais dos hospedeiros nos estudos de transmissão do Trypanosoma cruzi. Este método foi também utilizado como isca em medidas de controle, conforme demonstrado por Lima et al (1991Lima et al ( , 1992 e Lima (1994); para manutenção de colônias em laboratório (Garcia et al 1975), além da utilização no xenodiagnóstico artificial. Neste último caso torna-se ainda mais indicado, já que podem ocorrer casos de reações alérgicas cutâneas às picadas desses insetos (Mott et al 1980, Costa et al 1981.…”