Ciclo biológico do Rhodnius milesi (Hemiptera: Reduviidae) e a atividade de extratos de plantas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Chagas disease is transmitted to humans through feces of hemoptrous insects, subfamily Triatominae, contaminated during blood feeding. The increase in Triatominae populations resistant to available insecticides, and the appearance of new potential vector species, such as Rhodnius milesi in the Amazon region, are two pressing concerns. Given the uncharted chemical diversity of Cerrado plants as sources of new active molecules, this study assessed the insecticidal properties and the insect development retarding capacities of Cerrado plant extracts on 4th stage (N4) R. milesi nymphs, through the monitoring of the insects biological cycle under laboratory conditions. Of the 67 plant extracts tested, 15 caused insect mortalities between 12.5 and 42.5%. Nine of the 15 active extracts were partitioned in a liquid-liquid system allowing the selection of the hexanic phase of the ethanolic extract of the Siparuna guianensis leaf, which was fractioned in an open silicon gel column. The fractions were grouped (G) according to their chromatographic CCD profiles. Group G6 manifested triatomicidal and toxicological activity on 4th instar R. milesi nymphs. An overall ecclosion rate of 94.2% was observed for eggs of the 1st instar nymphs, incubated for an average of 15 days. The average pos-embrionary development period was 17.2 days for 1st instar nymphs, 18.2 for 2nd instar nymphs, 17.3 for 3rd instar, 20.5 for 4th instar, and 32.5 days for 5th instar nymphs, with 1 to 1.5 blood feedings in each stage. The average period between the ecclosion of the nymphs and the adult R. milesi was 105.7 days. The total mortality percentage was 11.5%; 4.9% for N1; 3.2% for N2; 2.7% for N3; and 0.7% for N5. However, no deaths were registered for N4, which corroborates the use of N4 nymphs in insecticidal activity studies. The average period of resistance to starvation for 5th instar nymphs was 333.5 days. This study is an initial investigation of the triatomicidal activity of S. guianensis, and is the first description of the reproductive cycle of R. milesi under laboratory conditions.

ASSUNTO(S)

siparuna guianensis rhodnius milesi plant extracts ciclo de vida ciencias da saude cerrado extratos de plantas doença de chagas cerrado triatomíneos life cycle siparuna guianensis triatominae rhodnius milesi chagas disease

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