Possible interference of Bacillus thuringiensis in the survival and behavior of Africanized honey bees (Apis mellifera)

Gabriela Libardoni,Raiza Abati,Fabiana Martins Costa-Maia,Edgar de Souza Vismara,Michele Potrich,Everton Ricardi Lozano,Pedro Manuel Oliveira Janeiro Neves,Amanda Roberta Sampaio

doi:10.1038/s41598-021-82874-1

Abstract

Bacillus thuringiensis (Bt), an entomopathogenic bacterium, has been used as bioinsecticides for insect pest control worldwide. Consequently, the objective of this work was to evaluate the possible effects of commercial formulations of Bt products, Dipel and Xentari, on the survival and behavior of Africanized honey bees (Apis mellifera). Bioassays were performed on foragers and newly emerged (24-h-old) bees that received the products mixed in the food. Their survival and behavior were evaluated through the vertical displacement tests and the walk test, analyzed using software Bee-Move. Then, histological analysis of the mesenterium was performed. As control treatment was used sterile water. The honey bees’ survival was evaluated for between 1 and 144 h. No interference of B. thuringiensis, Dipel and Xentari, in the survival of Africanized honey bees were found. Only Xentari interfered with vertical displacement behavior of newly emerged (24-h-old) bees. Both the products tested were selective and safe for A. mellifera.

Highlights

Bacillus thuringiensis (Bt), an entomopathogenic bacterium, has been used as bioinsecticides for insect pest control worldwide
As the mode of action of the bacteria is by ingestion and there is the possibility that these agents will be ingested by honey bees, the objective of this work was to evaluate the possible interference of the commercial formulated products containing B. thuringiensis on the survival and behavior of Africanized honey bees (A. mellifera)
The pathogenicity of B. thuringiensis depends on the ingestion of bacterial proteins by the insect

Summary

Introduction

Bacillus thuringiensis (Bt), an entomopathogenic bacterium, has been used as bioinsecticides for insect pest control worldwide. Bioassays were performed on foragers and newly emerged (24-h-old) bees that received the products mixed in the food. Their survival and behavior were evaluated through the vertical displacement tests and the walk test, analyzed using software BeeMove. Xentari interfered with vertical displacement behavior of newly emerged (24-h-old) bees Both the products tested were selective and safe for A. mellifera. The honey bees can be a biological indicator of environmental pollution and, the use of them as a monitor contributes to the ecological impact statement on the presence of agrochemicals, especially pesticides[1,2] It is a pollinating species of great importance, as it can visit twice as many flowers as other bees[3].

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