Acetogenin as tool to control Aedes aegypti: a perspective of toxicity and gene regulation

• Ano de defesa: 2016
• Autor(a) principal: Costa, Marilza da Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Dengue - Controle; Aedes aegypti - Controle; Acetogenina; Inseticidas vegetais; Resistência aos inseticidas; Entomologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/26690

Dengue, Chikungunya and Zika are arboviruses transmitted mainly by the mosquito Aedes aegypti. Although the control of this insect vector has been accomplished by eliminating rearing sites, use of biological control, genetic methods and the use of insecticides, it is important the use alternative control strategies for the integrated management of this pest. Thus it is expected decrease in the emergence of resistant mosquito strains and in the environmental risks and toxicology. This work evaluated a secondary metabolite of Annonaceae plant with insecticidal properties in the control of A. aegypti larvae. In the first step an acetogenin of Annona mucosa seeds was isolated and tested against A. aegypti larvae (target insect), its predators Culex bigotti and Toxorhynchites theobaldi (non-target insects) and on human leukocytes. The second step evaluated the morphology of the midgut cell in larvae exposed to acetogenin and the effect of this molecule in the expression of genes for autophagy (Atg1 and Atg8), V-H+-ATPase (membrane carrier protein) and aquaporin -4 (Aqp4) (water channel protein). The third step tested the effect of acetogenin on anal papilla of A. aegypti larvae, on the morphology expression of V-H+ -ATPase and Aqp4. The isolated molecule was squamocin that showed high toxicity to the A. aegypti larvae, but without toxicity to non-target insects and human leukocytes, indicating the selectivity of this molecule. In the midgut, squamocin showed cytotoxic effects in the digestive cells, increased expression of genes for autophagy (Atg1 and Atg8), decrease of V-ATPase and Aqp4 expression in LC20 as well as their inhibition in LC50, showing multiple modes of action in this organ. In anal papillae, squamocin caused morphological damages in the epithelium, decreased transcription levels of AaAQP4 and inhibited the AaV-H + -ATPase transcription, suggesting effect in the osmoregulation process of this organ. The modes of action of squamocin at morpho- physiological and molecular levels are described for the first time. Our results indicated that squamocin can be a prototype of natural products with potential to control A. aegypti larvae, contributing to the establishment of alternative strategies for the control of insect vectors with high efficiency and low environmental impact.