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Exposure of Africanized honey bees Apis mellifera to chitosan nanoparticles carriers of dimethoate

Grant number: 18/04329-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2018
Effective date (End): December 31, 2018
Field of knowledge:Biological Sciences - Zoology
Principal Investigator:Osmar Malaspina
Grantee:Ana Luiza Mendes dos Reis
Home Institution: Centro de Estudos de Insetos Sociais (CEIS). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

The transport system of biocides and pesticides by biodegradable nanoparticles is an innovative technological method and its application in agriculture has been gaining interest in recent years, since these nanoparticles are being developed with the objective of promoting the controlled release of substances over time. Due to these characteristics, this system would reduce the need for consecutive applications in agricultural crops, minimizing contamination of the soil and the environment, but maintaining the physicochemical characteristics of the substance stabilized in the nanoparticle. However, these nanoparticles need to be evaluated for their toxicity to non-target organisms, as well as the components of their formulation. To date, there are not even parameters for these tests in organisms, which need to be evaluated against the rapid development of nanotechnology. Non-target organisms that are exposed to the risks of pesticide-carrying nanoparticles include bees, which are important pollinator insects in areas of native vegetation and agricultural crops, which threatens the conservation of the forests and food security. They represent the main pollinator agents of plant species, and their key role in ecosystem services has already been threatened by the intensified use of pesticides of traditional application, and the question that needs to be answered is whether this new technological method can exert toxicological effects or not in bees. Thus, this project propose the toxicity evaluation of chitosan carrier nanoparticles of insecticide dimethoate in Apis mellifera bees, as well as nanoparticles of chitosan (without insecticide) and dimethoate in its free form, for comparative purposes. The parameters of analysis will be the determination of lethal time and analysis of the brain. The organ will be submitted to immunofluorescence analysis to evaluate the proteins of the HSP 70 family, and it is proposed to correlate the intensity level of the immunoreactivity of these cellular stress proteins with DNA fragmentation marking technique, indicative of cell death. In addition, the project intends to evaluate the enzymatic activity of acetylcholinesterase in the bees' brain, because of the neurotoxic action of dimethoate. The results of this work will contribute to the argumentation for the conservation of these pollinators, as well as to contribute with innovation research, analyzing the possible nanotoxic effects of alternative systems carrying pesticides, an area in poor development that is still little explored at the present time as to its effects on the environment and biota.