Glyphosate-based herbicides and Nosema sp. microsporidia reduce honey bee (Apis mellifera L.) survivability under laboratory conditions

Abstract

Reduction in the population of pollinators can compromise the stability of natural and agricultural ecosystems. One cause of this reduction is contact between pollinators and pesticides. More specifically, pollen and nectar which contain pesticide residues are carried into the colony, in turn, decreasing the resistance of bees to parasites. Therefore, this study aimed to evaluate the mortality and food consumption of Apis mellifera workers infected, or not, with Nosema microsporidia spores and exposed to a diet containing Roundup^® at the field dose recommended by the manufacturer. Each bioassay was composed of four dietary treatments: control, Roundup^®, Nosema microsporidia spores, and both Roundup^® and Nosema microsporidia spores. Results of both winter and spring bioassays showed that the interaction between Roundup^® and Nosema microsporidia significantly reduced survival rate and increased food consumption of the bees. Therefore, it can be concluded that the large amounts of glyphosate-based herbicides employed on extensive monocultures can, under current agroecosystem conditions, compromise the survival of A. mellifera colonies.

Keywords:

• Nosemosis
• Roundup^®
• mortality
• interaction pesticides x parasites

Acknowledgements

We thank Dr. Lilian de Oliveira Machado for her assistance in the molecular identification of Nosema spp. and Mrs. Yasmin Seemann Sbruzzi for her contribution to bee survival bioassays. We thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001 and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the scholarships to MRF and RON, respectively. This study was also financed, in part, by Genok – Centre of Biosafety, Norway.

Disclosure statement

The authors declare no conflicts of interest.