Over the last 20 years, hundreds of scientific publications have reported the adverse effects of neonicotinoids (neonics) on pollinating insects. Despite this, their use continues to grow. Europe’s warnings, based on the precautionary principle, did not impact the growing popularity of these products in Canada. One argument often made in favor of using neonics is their specificity for insects. This is true: even very low concentrations affect honey bees. The safety of neonics for vertebrates is now being challenged based on a series of studies reporting effects on the nervous system of rats.1,2 Neonics affect terrestrial wildlife (by their persistence in soil) and aquatic fauna due to concentration in rivers draining agricultural regions. Have we learned nothing from the previous example of DDT?
In my opinion, the use of neonics in most agroecosystems is not necessary. Firstly, most major Canadian crops are already genetically engineered to fight against pests. Secondly, several studies have revealed that the neonics' insecticidal power was too weak to be really effective and, ultimately, the yields associated with neonic-coated seeds did not exceed those from non-coated seeds, which does not justify the investment of farmers in terms of cost-benefit. With so much scientific evidence accumulated against neonics, Canada, like other countries, should apply the precautionary principle and ban the use.
Depuis une vingtaine d'années, des centaines de publications scientifiques ont relaté les effets néfastes des néonicotinoïdes (néocs) sur les insectes pollinisateurs. Malgré cela, on continue d’utiliser ces insecticides et aucune mise en garde basée sur le principe de précaution cher à l'Europe, n'a fait ombrage à la popularité grandissante de ces produits au Canada. Un des arguments en faveur de l'utilisation des néocs réside dans leur spécificité pour les insectes. En effet, de faibles concentrations affectent les abeilles. L'innocuité des néocs pour les vertébrés est maintenant remise en question suite à des études rapportant des effets sur le système cholinergique des rats.1,2 La faune terrestre ou aquatique est à risque car les néocs persistent dans le sol et on les retrouve dans les rivières qui drainent les régions agricoles. N'avons-nous rien appris de l'épisode DDT?
L'utilisation des néocs en agriculture m'apparaît superflu. D'abord, la majorité de l’agriculture canadienne de grande envergure utilise déjà des semences génétiquement modifiées pour lutter contre les insectes ravageurs. Ensuite, plusieurs études ont révélé que le pouvoir insecticide des néocs est trop faible pour être efficace et qu'en fait, le rendement des semences traitées aux néocs ne dépasse pas celui des semences non traitées, ne justifiant pas alors l'investissement des agriculteurs en termes de coûts/bénéfices. Étant donné les preuves scientifiques contre les néonicotinoïdes, le Canada, à l'instar d'autres pays, devrait appliquer le principe de précaution et bannir leur usage.
Sheila R. Colla is an Assistant Professor at the Faculty of Environmental Studies at York University and a Liber Ero Fellow. Her research has broadly looked at assessing status and threats to wild pollinators and understanding their ecological requirements. She is the IUCN SSC Bumble Bee Specialist Group’s North American Coordinator (with Dr. Robbin Thorp), a member of the COSEWIC Arthropod subcommittee and Acting Chair of the Committee on the Status of At-Risk Species in Ontario (COSSARO).
The current scientific evidence on the negative impacts of neonicotinoids on wildlife is very compelling and is growing rapidly. There are numerous peer-reviewed studies showing lethal and sublethal effects on a variety of taxa. In fact, I have yet to see a published study on an un-managed species which indicates neonicotinoids do not pose any threats. While this class of pesticides cannot be blamed for the reduction of any single species throughout their range, it likely poses additional direct and/or indirect stress to at-risk species occurring where these pesticides are used. These likely include many grassland specialists, species occurring in agriculturally intensified regions of Canada such as southern Ontario and flying insectivores. The possible effects on lesser studied (i.e. un-assessed) aquatic and soil-dwelling invertebrates are of particular concern as this may affect the future sustainability of our agricultural systems and natural ecosystems due to the reduction of ecosystem services they provide.
In my opinion, a full ban of neonicotinoids will not solve all of the problems which have been brought to light with this issue, but it would be a good first step. The reality is that pesticides by definition are developed to kill living things. If this class is banned, another type will be developed and scientists will have to research their effects on wildlife. As Canadians, I believe we should be thinking about where are agricultural sector is heading and what the implications are for biodiversity and human health. Our national and provincial policies should be guided by the precautionary principle. Also, instead of the prophylactic use of pesticides which harm a wide variety of organisms, we should be promoting integrated pest management where pesticides should only be used where there is true need. Ideally, we would move away from large-scale monocultures which allow for a financially catastrophic pest outbreaks and instead promote small-scale, organic and environmentally responsible farming. Our increasing production of cash crops like corn for use as livestock feed, ethanol and in processed foods will continue to have substantial negative impacts on wildlife and human health, with or without a ban.
Paul Demers is an epidemiologist, and the Director of the Occupational Cancer Research Centre (Cancer Care Ontario), and a Professor with the Dalla Lana School of Public Health at the University of Toronto. He has been a member of many national and international expert panels dealing with occupational and environmental cancer for organizations such as the International Agency for Research on Cancer, the Royal Society of Canada, and many others.
In recent decades neonicotinoid pesticides have emerged as one of the most common classes of insecticides in use. Prior to being allowed for use in Canada and similar countries, pesticides need to undergo toxicologic testing under laboratory conditions. This testing can identify key toxic properties of these pesticides, such as effects on nicotinic acetylcholine receptors in insects and their relatively lower toxicity to mammals. However, lab tests are not always able to predict all environmental effects, such as their detrimental impact on bee populations, or human health effects.
Recently, the International Agency for Research on Cancer (IARC) evaluated the carcinogenicity of a number of very commonly used pesticides and re-classified some of them as probable and possible human carcinogens. These recent evaluations by IARC illustrate the importance of continuing to study pesticides that are deemed to be relatively safe and to conduct human studies to assess their impact on chronic diseases, such as cancer. Given the widespread use of neonicotinoid pesticides, further studies of potential human health effects are needed.
David Kreutzweiser (PhD) is a Research Scientist with Natural Resources Canada, Canadian Forest Service, leading a research group that investigates ecological impacts of forest management, disturbances, and pest control activities on aquatic and forest ecosystems. He is a member of the International Task Force on Systemic Pesticides, an IUCN advisory group on neonicotinoid insecticides.
There is increasing evidence from scientific studies that the widespread use of neonicotinoid insecticides (neonics) poses serious risk of harm to an array of non-target organisms. Some studies have shown that neonics are a leading contributor to honeybee and wild bee mortality3,4,5,6 and this has garnered much public attention and discussion. But recent reviews of the scientific literature found strong, mounting evidence that other organisms are also at risk in some areas. These include other insect pollinators, aquatic and terrestrial invertebrates, and birds.7,8,9,10,11
Most of these risks arise because neonics are pervasive and persistent in the environment where they are heavily used. In many agricultural and horticultural settings, neonics are widely, repeatedly, and often prophylactically applied as sprays or as seed coatings. Neonics are taken up by plants and distributed throughout all plant tissues, so that organisms that ingest any part of the plant (leaves, flowers, nectar, pollen, seeds, etc.) will be exposed. Neonics move in soils and readily leach into water. Under some conditions, effective concentrations can persist in surface water and soils for months to years.
Neonics play a small role in their use to control invasive forest insect species. In Canadian forest pest management settings, one neonicotinoid (imidacloprid) is currently registered for use against the invasive emerald ash borer in ash trees, but it is not widely used. A prudent response to these risks is not necessarily an outright ban on all neonicotinoids, but pest managers and regulators should be aware of the science-based evidence of risk, and mitigate accordingly. Strategic and targeted applications of neonics for some serious pest problems may be warranted, but only as an interim measure until other options are available or developed. Reductions in the widespread and prophylactic use of neonics, coupled with increased efforts in adopting integrated pest management strategies, should be encouraged.
E4D would like to thank our experts for their contribution, and helping advance informed discussions around public policy. In particular, we would like to thank Sheila Colla for assistance with panel development and coordination. Please direct media inquiries to firstname.lastname@example.org
Editor's note: E4D specifically did not engage with experts to discuss honeybees or pesticides for this panel, as these components of the debate have been covered thoroughly in other forums. Instead, we chose to focus on the as-yet unasked questions regarding native wildlife and human health.
1Boily M, Sarrasin B, DeBlois C, Aras P, Chagnon M. 2013. Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments. Environ Sci Pollut Res 20: 5603–14
2Kimura-Kuroda J, Komuta Y, Kuroda Y, Hayashi M, Kawano H. 2012. Nicotine-like effects of the neonicotinoid insecticides acetamiprid and imidacloprid on cerebellar neurons from neonatal rats. PLoS ONE 7(2): e32432. doi:10.1371/journal.pone.0032432
3Sanchez-Bayo, F. 2014. The trouble with neonictoinoids: chronic exposure to widely used insecticides kills bees and many other invertebrates. Science 346(6211):806-807
4Cressey, D. 2015. Bee studies stir up pesticide debate: the threat the neonicotinoids pose to bees becomes clearer. Nature 520:416.
5Raine, N.E., Gill, R.J. 2015. Tasteless pesticides affect bees in the field. Nature doi:10.1038/nature14391
6Rundlof, M., Andersson, G.K.S., Bommarco, R., Fries, I., Hederstrom, V., Herbertsson, L., Jonsson, O., Klatt, B.K., Pedersen, T.R., Yourstone, J., Smith, H.G. 2015. Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature doi:10.1038/nature14420
7Goulson, D. 2013. An overview of the environmental risks posed by neonicotinoid insecticides. Journal of Applied Ecology 50:977-987.
8Chagnon, M., Kreutzweiser, D., Mitchell, D., Morrissey, C., Noome, D., van der Sluijs, J. 2014. Risks of large scale use of systemic insecticides to ecosystem functioning and services. Environmental Science and Pollution Research 22:119-134
9Gibbons, D., Morrissey, C., Mineau, P. 2014. A review of the direct and indirect effects of neonicotinoids and fipronil on vertebrate wildlife. Environmental Science and Pollution Research 22:103-118.
10Pisa, L., Amaral-Rogers, V., Belzunces, L., Bonmatin, J-M., Downs, C., Goulson, D., Kreutzweiser, D., Krupke, C., Liess, M., McField, M., Morrissey, C., Noome, D., Settele, J., Simon-Delso, N., Stark, J, van der Sluijs, J., van Dyck, H., Wiemers, M. 2014. Effects of neonicotinoids and fipronil on non-target invertebrates. Environmental Science and Pollution Research 22:68-102.
11van der Sluijs, J., Amaral-Rogers, V., Belzunces, L., Bijleveld van Lexmond, M., Bonmatin, J-M., Chagnon, M., Downs, C., Furlan, L., Gibbons, D., Giorio, C., Girolami, V., Goulson, D., Kreutzweiser, D., Krupke, C., Liess, M., Long, E., McField, M., Mineau, P., Mitchell, E., Morrissey, C., Noome, D., Pisa, L., Settele, J., Simon-Delso, N., Stark, J., Tapparo, A., van Dyck, H., van Praagh, J., Whitehorn, P., Wiemers, M. 2014. Conclusions of the worldwide integrated assessment on the risks of neonicotinoids and fipronil to biodiversity and ecosystem functioning. Environmental Science and Pollution Research 22:148-154