Impact of acute oral exposure to paraquat and glyphosate on food consumption and survival rates of the African honeybee Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae)

Abstract

The Western honeybee (Apis mellifera) plays a crucial role in pollinating natural ecosystems and crops. They support global food production, maintenance of biodiversity, and generation of income from hive by-products. In modern agriculture, frequent use of chemicals, such as herbicides, exposes bees directly to their toxicity. Whereas the noxious effects of commonly used herbicides on honeybees have become an emerging concern worldwide, their toxicity on the African subspecies Apis mellifera scutellata Lepeletier is unknown. In this study, we exposed A. m. scutellata to field concentrations of both paraquat and glyphosate and determined their effects on bee food consumption and survival rates. We found that the mortality rates of bees upon herbicide ingestion were concentration dependent. Lethal doses of paraquat and glyphosate were 10.8 and 229.5 µg/bee, respectively. Our findings suggest that the African honeybee is susceptible to paraquat and tolerant to glyphosate than its European counterpart. This study provides a baseline to help in regulating herbicide use and/or establishing their safe concentrations to protect biodiversity, particularly the beneficial pollinator insects such as bees.