Bees are attracted to nectar containing common pesticides, scientists at Trinity College Dublin and Newcastle University have discovered. This could increase their chances of exposure to high levels of pesticides. Previous studies have suggested that exposure of this kind can affect bees’ fitness.
The research, published in the leading international peer-reviewed journal Nature, discovered that buff-tailed bumblebees and honeybees could not taste the three most commonly used ‘neonicotinoid’ pesticides and so did not avoid them. In fact, the bees showed a preference for food which contained pesticides: when the bees were given a choice between sugar solution, and sugar solution containing neonicotinoids, they chose the neonicotinoid-laced food.
The lab-based study also showed that the bumblebees ate more of the food containing pesticides than the honeybees, and so were exposed to higher doses of toxins.
Bees and other pollinating insects are important for increasing crop yields – their value has been estimated to be worth at least €153billion per year globally. When pollinating crops, they can be exposed to pesticides in floral nectar and pollen. Several controversial studies have shown that neonicotinoids have negative effects on bee foraging and colony fitness. As a result, public concern has grown over the impact of neonicotinoids on bees and other pollinators. In April 2013, the EU introduced a temporary ban on the use of neonicotinoid pesticides on flowering crops, while further scientific and technical evidence was gathered.
Professor of Botany and Principal Investigator in the School of Natural Sciences at Trinity College Dublin, Jane Stout, said: “Our findings imply that even if alternative food sources are provided for bees in agricultural landscapes where neonicotinoid pesticides are used, the bees may prefer to forage on the neonicotinoid-contaminated crops. Since neonicotinoids can also end up in wild plants growing adjacent to crops, they could be much more prevalent in bees’ diets than previously thought.”
Professor Geraldine Wright, lead scientist on the study at the Institute of Neuroscience at Newcastle University, said: “Bees can’t taste neonicotinoids in their food and therefore do not avoid these pesticides. This is putting them at risk of poisoning when they eat contaminated nectar.
“Even worse, we now have evidence that bees prefer to eat pesticide-contaminated food. Neonicotinoids target the same mechanisms in the bee brain that are affected by nicotine in the human brain. The fact that bees show a preference for food containing neonicotinoids is concerning as it suggests that like nicotine, neonicotinoids may act like a drug to make foods containing these substances more rewarding.
“If foraging bees prefer to collect nectar containing neonicotinoids, this could have a knock-on negative impact on whole colonies and on bee populations.”
The study was funded by Science Foundation Ireland, the Irish Research Council, and the National Science Foundation. It is also part of the Insect Pollinators Initiative, which is jointly funded by the Biotechnology and Biological Sciences Research Council (BBSRC), Defra, the Natural Environment Research Council (NERC), the Scottish Government and the Wellcome Trust under the auspices of the Living with Environmental Change (LWEC) partnership.
Launch of the European Academies Science Advisory Council (EASAC) Report: Ecosystem services, agriculture and neonicotinoids
A new independent scientific report prepared by EASAC, published on April 8th, 2015, concluded that there is significant evidence for negative effects associated with the widespread use of neonicotinoids on non-target organisms that provide ecosystem services like pollination and natural pest control.
The report highlights that the debate on whether neonicotinoids should be banned for use in certain crops should extend beyond honeybees, to include consideration of the impacts on soil health, other aspects of biodiversity like farmland birds, and other pollinators and natural enemies of crop pests. The report recognises the benefits of the use of insecticides for agricultural productivity, but argues that the risks to ecosystem services which underpin sustainable agriculture, as well as the wider biodiversity in agriculturally-dominated landscapes, need more consideration.
Dr Stout was the Royal Irish Academy nominee to EASAC’s Working Group that prepared the report. She said: “Although much of the public and political focus in the debate about neonicotinoids has been on honeybees, there is more and more evidence that widespread use of neonicotinoids could harm a range of organisms.
“This includes other species of bees and other pollinating insects, but also other ecosystem service providers like natural enemies of crop pests and soil organisms. If we are serious about sustainable agricultural production, and about maintaining biodiversity in agricultural ecosystems, a paradigm shift is needed in terms of crop protection – we shouldn’t be thinking about which chemicals will replace neonicotinoids if their ban continues, but about how to produce food and manage pests in a way in which chemical treatments are used as a last resort – not in a prophylactic way.”