Two new studies, both published by the journal Nature, are once again indicting the pesticide group, neonicotinoids, as having adverse affects on bee populations.
Washington Post:
A pair of new studies published Wednesday in Nature are disturbing when taken separately, but so much more chilling when laid out next to each other: The first provides new evidence that neonicotinoid insecticides can have a negative effect on bees, adding weight to the theory that these chemicals could contribute to colony collapse disorder and endanger our food supply. In the second study, another group of researchers found that bees don't avoid these harmful pesticides. They may actually seek them out and get addicted to them.
This class of insecticide has been highly controversial, with heated debate, but the data keeps coming in, and piling up, to the point that even the industry-coddling EPA has called for a moratorium on April 2nd, 2015, at long last joining the European Union which also placed a moratorium on the pesticide. It seems that step by step, blow by blow, the critics are being proven correct about the harmful affects of the chemical.
Salon:
At long, long long last, the Environmental Protection Agency is taking on neonicatinoids, the class of pesticides implicated in the mass die-offs of bees.
The agency announced Thursday that it will be restricting the future manufacture and use of products containing the pesticides; in letters sent to companies that apply those products outdoors, it warned that it likely won’t be approving new permits for their use until it can determine that they won’t cause “unreasonable adverse effects on the environment.”
The letters, the EPA said, “reiterate that the EPA has required new bee safety studies for its ongoing registration review process for the neonicotinoid pesticides, and that the Agency must complete its new pollinator risk assessments, which are based, in part, on the new data, before it will likely be able to make regulatory decisions…that would expand the current uses of these pesticides.”
Of the two new studies, one finds strong new evidence that the pesticide is negatively impacting the growth and reproductive abilities of wild bees, such as bumblebees and solitary bees.
Salon:
This is far from the first study establishing a likely connection between the insecticides, known as neonicotinoids, and bee well-being. Previous research has established that the chemicals, which have been placed under a temporary moratorium in Europe until more research can be done, can have neurological effects, like messing with bees’ ability to locate their hives and diminish their capacity to produce new queens, among other impacts. The new study adds to the conversation by studying how impacts seen in the lab are replicated in the field. Researchers looked at 16 rapeseed fields in Sweden, half of which used seeds that had been treated with neonicotinoids, and half of which had not. Populations of wild bees — bumblebees and solitary bees — surrounding the treated fields, they found, were nearly half as dense. Bumblebees exhibited slower growth rates and produced fewer queens, while the female solitary bees failed to reproduce.
So, the population of wild bees in proximity to the treated fields
were half as dense as the populations near the untreated fields. Half as dense... that's substantial. Most previous studies were not conducted in real world context, out in the field. This study is one of the fist to accomplish this, and the results are particularly unsettling.
As the researchers concluded:
Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees1, 2, 3 may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.
As it turns out, honey bees were not as badly affected as the wild bees, in terms of population density, possibly because of their much, much larger colonies which make them more able to sustain themselves and endure losses more easily. This brings to light a disturbing fact: most research of toxicity is conducted using honeybees, which means researchers may be missing the implications of toxicity to other pollinating insect like bumblebees.
As Josh Dzieza at The Verge points out:
The finding that honey bees didn’t show signs of harm shouldn’t be a complete surprise either. Honey bees live in such large colonies and regenerate so quickly that thousands of bees can die without significantly effecting the hive. Their resilience is part of the reason they’re used for migratory crop pollination, rather than bumblebees, which live in colonies of tens or hundreds, or solitary bees. Previous work suggests honey bees may also be better at detoxifying after neonicotinoid exposure than bumblebees. The researchers also caution that their study shouldn’t be taken as a sign that honey bees aren’t harmed at all: because so much can vary in a field study, anything less than a 20 percent decline in colony size wouldn’t be detected, and there could be longer-term effects.
"This is certainly the most decisive work we’ve seen on neonics at field-relevant doses," says Dennis vanEngelsdorp, an entomologist at the University of Maryland bee laboratory.
Bee experts are hailing the study as significant, even a turning point in research:
The Guardian:
Dr Maj Rundlöf, the lead author of the study, said the impacts on wild bees were “dramatic”. “I think it’s really important evidence when discussing how neonicotinoids used in real agricultural landscapes influence bees,” she said.
Dave Goulson, a bee expert at Sussex University, not involved in the research, hailed the findings as hugely significant.
“At this point in time it is no longer credible to argue that agricultural use of neonicotinoids does not harm wild bees.” He said the paper was “a major step forwards in clarifying the neonicotinoid debate ... This was the first fully field-realistic, well-replicated trial so far, an impressive piece of work.”
The second study, also published in Nature on the same day, reports that bees favor pollen and nectar of plants treated with the pesticide.
Salon:
This [first study] matters more than ever, because the second study makes clear that bees aren’t going to avoid these dangerous chemicals on their own — as some have suggested they might. Researchers presented bumblebees and honeybees with a choice between two treats: sugar water, and a sugar solution containing low doses of bitter neonicotinoids. The bees didn’t seem able to taste the difference, but they kept coming back for the chemical-laced option. The bumblebees, which we now know are specifically harmed by neonicotinoids, seemed particularly partial to them.
Why would bees be attracted to a chemical that negatively affects their motor functioning? Basically, the researchers say, they’re getting buzzed.
“Neonicotinoids target the same mechanisms in the bee brain that are affected by nicotine in the human brain,” lead author Geraldine Wright explained in a statement. “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.”
As the researchers pointed out, it has
been asserted that bees tend to avoid neonicotinoid-treated crops, reducing their exposure. This study draws this assertion into question, and show that bees in fact are drawn to the pesticide.
Washington Post:
“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," lead author Geraldine Wright said in a statement. “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.”
Excerpt from the abstract of actual study:
Here, using a two-choice feeding assay, we show that the honeybee, Apis mellifera, and the buff-tailed bumblebee, Bombus terrestris, do not avoid nectar-relevant concentrations of three of the most commonly used neonicotinoids, imidacloprid (IMD), thiamethoxam (TMX), and clothianidin (CLO), in food. Moreover, bees of both species prefer to eat more of sucrose solutions laced with IMD or TMX than sucrose alone. Stimulation with IMD, TMX and CLO neither elicited spiking responses from gustatory neurons in the bees’ mouthparts, nor inhibited the responses of sucrose-sensitive neurons. Our data indicate that bees cannot taste neonicotinoids and are not repelled by them. Instead, bees preferred solutions containing IMD or TMX, even though the consumption of these pesticides caused them to eat less food overall. This work shows that bees cannot control their exposure to neonicotinoids in food and implies that treating flowering crops with IMD and TMX presents a sizeable hazard to foraging bees.
Full abstracts of both studies are below the fold:
Seed coating with a neonicotinoid insecticide negatively affects wild bees
Maj Rundlöf, Georg K. S. Andersson, Riccardo Bommarco, Ingemar Fries, Veronica Hederström, Lina Herbertsson, Ove Jonsson, Björn K. Klatt, Thorsten R. Pedersen, Johanna Yourstone & Henrik G. Smith
Nature 521, 77–80 (07 May 2015) doi:10.1038/nature14420
Received 11 July 2014, Accepted 26 March 2015, Published online 22 April 2015
Understanding the effects of neonicotinoid insecticides on bees is vital because of reported declines in bee diversity and distribution1, 2, 3 and the crucial role bees have as pollinators in ecosystems and agriculture4. Neonicotinoids are suspected to pose an unacceptable risk to bees, partly because of their systemic uptake in plants5, and the European Union has therefore introduced a moratorium on three neonicotinoids as seed coatings in flowering crops that attract bees6. The moratorium has been criticized for being based on weak evidence7, particularly because effects have mostly been measured on bees that have been artificially fed neonicotinoids8, 9, 10, 11. Thus, the key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes11, 12, 13. Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees1, 2, 3 may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.
Bees prefer foods containing neonicotinoid pesticides
Sébastien C. Kessler, Erin Jo Tiedeken, Kerry L. Simcock, Sophie Derveau, Jessica Mitchell, Samantha Softley, Jane C. Stout & Geraldine A. Wright
Nature 521, 74–76 (07 May 2015) doi:10.1038/nature14414
Received 24 January 2015, Accepted 20 March 2015, Published online 22 April 2015
The impact of neonicotinoid insecticides on insect pollinators is highly controversial. Sublethal concentrations alter the behaviour of social bees and reduce survival of entire colonies1, 2, 3. However, critics argue that the reported negative effects only arise from neonicotinoid concentrations that are greater than those found in the nectar and pollen of pesticide-treated plants4. Furthermore, it has been suggested that bees could choose to forage on other available flowers and hence avoid or dilute exposure4, 5. Here, using a two-choice feeding assay, we show that the honeybee, Apis mellifera, and the buff-tailed bumblebee, Bombus terrestris, do not avoid nectar-relevant concentrations of three of the most commonly used neonicotinoids, imidacloprid (IMD), thiamethoxam (TMX), and clothianidin (CLO), in food. Moreover, bees of both species prefer to eat more of sucrose solutions laced with IMD or TMX than sucrose alone. Stimulation with IMD, TMX and CLO neither elicited spiking responses from gustatory neurons in the bees’ mouthparts, nor inhibited the responses of sucrose-sensitive neurons. Our data indicate that bees cannot taste neonicotinoids and are not repelled by them. Instead, bees preferred solutions containing IMD or TMX, even though the consumption of these pesticides caused them to eat less food overall. This work shows that bees cannot control their exposure to neonicotinoids in food and implies that treating flowering crops with IMD and TMX presents a sizeable hazard to foraging bees.