Alterations in the brain and midgut of bees Apis mellifera exposed to imidacloprid

Author(s)

Aline Fernanda Catae

• Document type: Master's Dissertation
• Press: Rio Claro. 2016-08-22.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2016-07-25
• Advisor: Osmar Malaspina; Thaisa Cristina Roat

Abstract

The bees Apis mellifera stand out significantly in the economic and ecological context for products supplied as propolis, royal jelly, honey, beeswax and venom, and because the extreme importance that the pollination process is for the equilibrium of ecosystems. Current studies indicate that some synthetic substances used to control pests in agriculture may be involved in cases of intoxication of bees. The effects of these products may not be immediately noticeable, but they can cause serious physiological and behavioral effects that can compromise the viability of the colony. Given the above, this work had as main objectives: to evaluate the oral toxicity of imidacloprid to A. mellifera through the determination of the lethal concentration (LC50), and analyse the effects of a sublethal concentration (LC50/100) in the midgut and brain through transmission electron microscopy as well as the distribution of proteins in the brain, by MALDI-Imaging technique. The LC50 value established to imidacloprid was 1.4651 ng/μL diet. The exposure to LC50/100 (0.0146 ng imidacloprid/μL diet) caused quite significant alterations in ventricular cells, especially after the fourth day of exposure, such as reduction of the size of the nucleus, chromatin condensation, mitochondrial alterations and increased of digestive and cytoplasmic vacuoles. In the brain, it was possible to observe mitochondrial damages, spacing among cells, irregular nuclei and dilation in the perinuclear space. This sublethal concentration also affected the spatial distribution of several proteins in the brains of bees, mainly involved in synapse processes, oxygen supply, chemical and oxidative stress, neuronal degeneration, learning and memory, demonstrating that this insecticide cause biochemical changes that can derail important neuronal functions. (AU)

• FAPESP's process: 14/14070-3 - Effects of imidacloprid on proteins distribution in the brain of Melipona scutellaris Latreille, 1811 (Hymenoptera, Apidae, Meliponini)
• Grantee: Aline Fernanda Catae
• Support Opportunities: Scholarships in Brazil - Master