Ultra-structural Changes of Aedes aegypti Larvae Submitted to Treatment with Formulated Product

Bioactive products have been used against Aedes aegypti larvae. This study aimed to evaluate the ultrastructural changes of Aedes aegypti larvae submitted to treatment with a product formulated containing oils of Azadirachta indica, Melaleuca alternifolia, Carapa guianensis, and fermented extract of Carica papaya. The larvicidal assay was performed with third-stage larvae of A. aegypti, in triplicate (n = 900) for 24h. The experimental groups were G1 (50%), G2 (25%), and G3 (12.5%). Positive controls with industrial larvicide (Bacillus thuringiensis Israeli variety) at 0.37ppm (CP1) and 0.06ppm (CP2) concentrations. Finally, negative controls were water (CN1) and dimethyl sulfoxide (CN2). Specimens were collected from all groups for ultrastructural scanning by the end of the experiment, fixed in 2.5% buffered glutaraldehyde, and post-fixed in 2% osmium tetroxide. Then, all samples were routinely processed by scanning electron microscopy. The larvae treated with 12.5% (G3) of the formulated product showed wrinkling, skin damage, head, and chest rupture with exposure of the underlying musculature. We conclude that the formulated product containing oils of Azadirachta indica, Melaleuca alternifolia, Carapa guianensis, and fermented extract of Carica papaya promoted ultrastructural changes and death of A. aegypti third-stage larvae, being effective to control diseases propagated by this vector