Metabolism and performance of silkworms well and poorly nourished and contaminated with a triple action fungicide

• Grant number: 22/08532-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2022
• End date: May 31, 2023
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Ecology of Domestic Animals and Ethology
• Principal Investigator: Daniel Nicodemo
• Grantee: Gabriela Rodrigues Mendes
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

Sericulture is an important agro-industrial activity in Brazil, which is the fourth largest producer of green cocoons and silk thread. Silk quality can be related with mulberry (Morus spp.) growing conditions, such as weather, cultivation spacing, water availability for plants, soil types, branch pruning, leaf growth, among others, including factors unrelated to sericulture. The ecological imbalance inherent in the cultivation of extensive areas with monocultures implies the use of large amounts of pesticides. Among the phytochemical products, fungicides stand out, as their recurrent use has led to the selection of resistant phytopathogenic fungi. In this way, higher doses of fungicides are used in the field, until products with new active ingredients are made available to farmers. A new strategy to combat phytopathogenic fungi is the formulation of fungicides with three active principles, aiming to control fungal populations at different stages of the life cycle. If this alternative has shown to be promising from an agronomic point of view, for cocoon producers such a measure can be worrying. Although they are insects, the main mode of action of some fungicides, the inhibition of mitochondrial respiration, impairs the development of caterpillars. However, the nutritional status of this insect must be considered, given that nutritional deficiencies may imply greater susceptibility to stress agents, such as fungicides. In this study, we will study the effect of trifloxystrobin, prothioconazole and bixafem, which are the active ingredients that make up a commercial fungicide used in large agricultural crops. Assays will be carried out to elucidate the effect of these active principles on mitochondrial bioenergetics and oxidative stress in silkworm (Bombyx mori) caterpillars, which will receive diets of high and low nutritional value. In addition, the quality of cocoons produced by silkworm caterpillars that will consume mulberry leaves obtained from plants treated with the triple action fungicide will be verified. Therefore, it will be possible to verify if the eventual metabolic damages and damages inherent to the gene expression in this insect are smaller when the individuals are fed with diets of high nutritional value.