Study Reveals Bumblebees Cannot Detect Lethal Levels of Pesticides


New research conducted by the University of Oxford has discovered that bumblebees are unable to taste pesticides present in nectar, even at levels that are lethal. This revelation presents a significant risk to bumblebees as they are unable to avoid contaminated nectar, ultimately posing a threat to crop pollination.

Bees play a crucial role in pollinating agricultural crops, which unfortunately exposes them to pesticides while they gather nectar and pollen. Many of these pesticides are highly toxic to bees. It is widely known that bees possess a strong ability to differentiate between different sugary solutions. For instance, bees can taste bitter compounds, such as quinine. In light of this, the researchers sought to determine whether this sense of taste could help bees avoid pesticide-laden nectar.

In order to conduct their study, the researchers employed two methods. Firstly, they used electrophysiology to record the responses of neurons in taste sensilla, or ‘tastebuds,’ found on the bumblebees’ mouthparts. This allowed them to measure how frequently neurons ‘fired,’ indicating the strength of their response to taste. Secondly, they tested the bees’ feeding behavior by offering them sugar solutions without pesticides, as well as sugar solutions containing pesticides.

The results showed that the neurons exhibited identical responses whether the bees consumed sugar solutions or sugar-containing pesticides. This implies that bumblebees lack the ability to detect and avoid common pesticides found in nectar.

Interestingly, in the behavior experiments, the bumblebees consumed the same amount of food irrespective of whether the solution contained pesticides or not. This remained true even when the pesticides were present in concentrations that would make the bees severely ill.

The implications of these findings are significant, as they demonstrate that bumblebees are unable to use their sense of taste to avoid pesticide exposure. Consequently, this poses a considerable risk to bees when it comes to pesticide use on outdoor crops.

Lead author of the study, Dr. Rachel Parkinson from the Department of Biology at the University of Oxford, commented, “As bumblebees cannot taste pesticides and don’t experience immediate negative consequences from drinking them, they likely would not be able to avoid consuming nectar contaminated with pesticides in the field.”

Dr. Parkinson added, “Potentially, these findings could be applied towards searching for a non-toxic compound that tastes bad to bees and could be used as a bee deterrent on pesticide-treated crops that do not require insect pollination.”

Although the bees did not consume less of the pesticide-laced solutions, the researchers demonstrated bitter taste avoidance using the compound quinine. At high concentrations, quinine in sugar solution acted as a deterrent to the bees. In the case of lower concentrations, the bees ingested smaller amounts of the sugar solution, yet the amount of time they spent in contact with the feeding solution remained the same.

The pesticides used in the study included the neonicotinoids imidacloprid, thiamethoxam, clothianidin, and the sulfoximine pesticide sulfoxaflor.

In conclusion, this study sheds light on the inability of bumblebees to detect lethal concentrations of pesticides in nectar. This lack of taste sensitivity poses a significant risk to bees and crop pollination. The findings highlight the need to search for alternative, non-toxic compounds that can deter bees from pesticide-treated crops that do not rely on insect pollination. Implementing such alternatives could help mitigate the potential harm caused by pesticide exposure to bees and their crucial role in pollination.

1. Source: Coherent Market Insights, Public sources, Desk research
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