ABSTRACT
The study evaluated the effects of R-limonene, in sublethal concentration, on the histology, histochemistry, biochemistry, and carbohydrates and proteins levels in the third instar Aedes aegypti larvae. The R-limonene (LC50 of 27 ppm) and control groups were analyzed 12 and 24 h after the beginning of treatments. The midgut of the control larvae was composed of cylindrical and elongated cells with a spherical and central nucleus and regenerative cells with a pyramidal shape. After 12 h of treatment, columnar cells, protuberances, and cytoplasmic vacuolization were found. However, 24 h after treatment, complete disorganization of the epithelium was observed. There was a positive reaction in all treatments for the presence of glycogen. However, the midgut of larvae treated with R-limonene showed higher levels. For the total protein, positive marking occurred in all groups evaluated, with higher levels in treatments and the lowest in control 12 h. The levels of total protein and glycogen increased in the treated larvae compared to the 12 h control. Besides, a reduction in total sugar levels was observed in the treated larvae compared to controls 12 and 24 h, being more evident in the last one. Therefore, these results demonstrate that R-Limonene caused pathological changes in the epithelium of the A. aegypti midgut at histophysiological and biochemical levels.
Subject(s)
Aedes , Insecticides , Limonene , Animals , Larva , Plant ExtractsABSTRACT
Products with Bacillus thuringiensis (Bt) and synthetic insecticides have been widely used against important vectors of human diseases. However, few studies have addressed the application of these substances on the female reproduction apparatus during pregnancy at doses that do not cause clinical symptoms of intoxication. Seventy pregnant albino rats were analyzed with regard to fertility and histopathology of the kidneys, liver and lungs as well as the morphology of the neonates. The rats were submitted to three sub-lethal doses of the biological insecticide XenTari(®) WG (B. thuringiensis subsp. Aizawai) and the synthetic insecticide deltamethrin (Decis(®) 25CE). After the confirmation of copulation, the insecticides were administered orally for either seven days or during the entire pregnancy. The analysis revealed histopathological alterations in all organs analyzed in both treatments. No miscarriages occurred and the neonates did not exhibit signs of malformation of the head, limbs, thorax or abdomen. However, there were a smaller number of pups in the groups that received higher doses of the insecticides in comparison to the control group. Both insecticides produced similar lesions in the kidneys, liver and lungs and reduced the fertility of rats when administered at sub-lethal doses with no clinical signs of intoxication. Thus, this study suggests that sublethal doses of both insecticides can provide chronic toxicity in humans.
