Avaliação do efeito do R-Limoneno, em concentração subletal, sobre a histologia e histoquímica do intestino médio, e compostos energéticos em larvas de Aedes Aegypti L. (Diptera: Culicidae)

Abstract

Aedes aegypti is the main transmitter of dengue in 128 countries. Approximately 390 million people are infected and 20,000 of those die each year. The monoterpenes are efficient larvicides against this vector, among them the limonene acts in the midgut of the larvae, interfering in its development. The objective of the research was to evaluate the action of limonene, in sublethal concentration, on histology, histochemistry of midle intestine, and levels of neutral carbohydrates and total proteins in Ae. aegypti larvae. Bioassays of 3rd instar larvae were used. Limonene was used at the LC50 of 27 ppm. The treatments were: limonene and control (water and ethanol), analyzed after 12 and 24 h. The midgut of the larvae treated after 12h presented columnar cells, protuberances and cytoplasmic vacuolization and after 24h there was total disorganization of the epithelium. Histochemically, the treated larvae had higher levels of glycogen when compared to the control group as well as for total protein. Biochemically, there was a significant increase in total protein levels in the treated larvae in relation to the 12 h control and reduction in relation to the 24 h control. There was an increase and reduction in glycogen and total sugar levels in the treated larvae in relation to the controls. It is concluded limonene causes pathological changes in histology and histochemistry in the midgut of the Ae. aegypti larvae, besides interfering in proteins level, glycogen and total sugar.