Bees cannot taste even lethal levels of pesticides, says new study
New research from the University of Oxford appears to reveal that bumblebees cannot taste pesticides present in nectar, plane at lethal concentrations. This ways bumblebees are not worldly-wise to stave contaminated nectar, putting them at upper risk of pesticide exposure and posing a threat to yield pollination.
Bees are important pollinators of agricultural crops, but this can expose them to pesticides while they collect nectar and pollen – some of which are very toxic to bees. Bees are known to be whiz at tasting and differentiating sugary solutions. Certain toxic compounds, like quinine, taste “bitter” to bees, so the researchers sought to find out whether this sense of taste could help them stave drinking pesticides.
The researchers used two methods to test whether bumblebees (Bombus terrestris) could taste neonicotinoid and sulfoximine pesticides in nectar which mimicked that of oilseed rape (Brassica napus), and if they would stave drinking pesticides over a very wholesale range of concentrations. They used electrophysiology to record the responses of neurons in taste sensilla (i.e., ‘tastebuds’) on bumblebee’s mouthparts. This unliable them to track how often neurons ‘fired’ and therefore the strength of response to the taste. The researchers moreover tested the bumblebees’ feeding behaviour by offering them either sugar solutions or pesticide-laced sugar solutions to feed on.
The results demonstrated that the responses of the neurons were the same whether the bees drank sugar solution or sugar-containing pesticides. This indicates that the bumblebees’ mouthparts do not have mechanisms to snift and stave worldwide pesticides in nectar.
In the behaviour experiments, the bees consumed the same value of food, regardless of whether the solution contained pesticides or not. This was plane the specimen when the pesticides were present at concentrations upper unbearable to make the bees very ill.
The findings are important considering they show that bumblebees cannot stave pesticide exposure using their sense of taste.
Lead tragedian Dr Rachel Parkinson (Department of Biology, University of Oxford), said: ‘As bumblebees cannot taste pesticides and don’t wits firsthand negative consequences from drinking them, they likely would not be worldly-wise to stave consuming nectar contaminated with pesticides in the field.’
Dr Parkinson added: ‘This research is important when considering the use of pesticides on outdoor crops due to the risk posed to bees as they will not stave drinking these compounds. Potentially, these findings could be unromantic towards searching for a non-toxic recipe that tastes bad to bees and could be used as a “bee deterrent” on pesticide-treated crops that do not require insect pollination.’
Although bees did not drink less of the pesticide-laced solutions, the authors demonstrated “bitter” taste avoidance using the recipe quinine. Quinine in sugar solution was deterrent to bees at upper concentrations. At low concentrations, bees were observed to ingest less of the sugar solution, however the value of time they spent in contact with the feeding solution was the same.
The paper ‘Mouthparts of the bumblebee (Bombus terrestris) walkout poor vigilance for the detection of pesticides in nectar’, published in eLife, is misogynist online at https://doi.org/10.7554/eLife.89129.2