Desenvolvimento de bioprodutos derivados do líquido da casca da castanha de caju técnico com potencial larvicida contra Aedes aegypti (Diptera: Culicidae)

Abstract

Dengue, Zika, Chikungunya and Yellow Fever viruses have, in common, the same transmission vector, Aedes aegypti mosquito. Ae. aegypti is an arthropod adapted to the urban and peri-urban environment, with higher incidence in tropical and subtropical countries. Among the arboviruses transmitted by Ae. aegypti, Dengue is among the diseases with the greatest social impact. Ae. aegypti populations control has been carried out through the use of chemical and/or biological insecticides and larvicides. However, the levels of resistance of the insect to the products normally used, make these forms of control inefficient. The search for new larvicidal products where we can highlight those from natural sources, especially those from agro-industrial waste, as they present technological simplicity, low cost, multifunctionality, and action in different microenvironments, constitute a viable alternative for vector control. It is important to note that the characteristics presented by this type of products link them to the principles of “Green Chemistry”. Particularly products based on agro-industrial residues of plant origin, can act as ovicides, larvicides, insect growth regulators, repellents and as attractive for oviposition. Among the different agro-industrial residues, we can highlight the technical Cashew Nut Shell Liquid (tCNSL), from the toasting of the cashew nut (Anacardium occidentale) with insecticidal and larvicidal activity against Ae. aegypti. Our objective was to produce new bioproducts obtained from partial neutralization of tCNL with inorganic (NaOH and KOH) and organic (MEA, DEA and TEA) bases and to evaluate their larvicidal activity for Ae. aegypti. bactericide and fungicide. In addition, also evaluate the toxicity of bioproducts in non-target organisms. The evaluation of the larvicidal activity of the self-emulsifiable bioproducts, obtained by partial neutralization of tCNSL, LCCtNa, LCCtK, LCCtMEA, LCCtDEA and LCCtTEA was carried out using Ae. aegypti 3rd and 4th instar larvae. To assess bioproducts ecotoxicological potential, chronic toxicity tests were performed with Pseudokirchneriella subcapitata (algae), and acute toxicity tests with Daphnia similis (microcrustaceans) and Oreochromis niloticus (fish). All bioproducts obtained presented larvicidal activity against Ae. aegypti. Bactericidal activity was observed for the LCCtNa, LCCtMEA, LCCtDEA and LCCtTEA, except LCCtK. None of the bioproducts showed fungicidal activity. Regarding the ecotoxicological effects, D. similis was the organism whit highest sensitivity for LCCtNa, LCCtK and LCCtDEA, followed by P. subcapitata and O. niloticus. For LCCtMEA and LCCtTEA, the most sensitive organisms were D. similis, followed by P. subcapitata and O. niloticus. Based on our results, the bioproducts obtained can be considered effective larvicides for Ae. aegypti control, in addition, in addition, as they come from agro-industrial residues, corroborate with the reduction of the environmental impact, complying with the principles of “Green Chemistry”, allowing the reduction of waste disposal in the environment.