Bees are capable of tasting nectar but are quite incapable of detecting pesticides present in nectar, even at levels that could prove lethal, said a recent study from the University of Oxford.
This inability leaves them vulnerable to exposure, posing a significant threat to both their well-being and the crucial role they play in crop pollination. The study, published in eLife, sheds light on a critical challenge facing these vital pollinators.
INABILITY TO DETECT CONTAMINATED NECTAR RAISES CONCERNS
Despite bees’ proficiency in distinguishing various sugary solutions, such as differentiating the bitterness of compounds like quinine, the research discovered that bumblebees (Bombus terrestris) could not detect neonicotinoid and sulfoximine pesticides in nectar mimicking that of oilseed rape (Brassica napus). This inability places them at high risk of pesticide exposure while foraging for nectar and pollen, potentially jeopardizing their health and crucial role in agriculture.
METHODS AND FINDINGS
Using electrophysiology to monitor taste sensilla on the bees’ mouthparts, researchers tracked the neuronal responses to sugar solutions and pesticide-laced nectar. Surprisingly, the neurons showed similar reactions regardless of whether the bees consumed sugar solutions or those containing pesticides. Behaviour experiments revealed that the bees consumed similar amounts of both types of solutions, even when pesticides were present at concentrations that could severely affect their health.
BEHAVIOR AND PESTICIDE EXPOSURE
Lead author Dr. Rachel Parkinson emphasized the significance of the findings, stating that as bumblebees cannot taste pesticides or experience immediate adverse effects, they are unlikely to avoid consuming pesticide-contaminated nectar in the natural environment. This lack of detection mechanisms raises grave concerns about the bees’ vulnerability to pesticide exposure and its potential impact on their health and well-being.
BITTER TASTE AVOIDANCE VS. PESTICIDE DETECTION BEES
While bees displayed aversion to high concentrations of quinine in sugar solutions, reducing their intake, the same avoidance behaviour was not observed with pesticide-laced solutions. Even at lower concentrations, bumblebees did not decrease their consumption, highlighting their inability to discern pesticide presence through taste despite exhibiting avoidance behaviour with bitter compounds.
The research underscores a critical challenge in protecting bee populations, emphasizing the urgent need to address the lack of detection mechanisms that could safeguard these vital pollinators from harmful pesticide exposure.
