European group says neonicotinoid use can’t be sustainable

A European expert group has looked at the impact of neonicotinoid pesticides on the benefits that ecosystems provide for agriculture, broadening their focus beyond honeybees. The conclusions of the report by the European Academies Science Advisory Council (EASAC), which reviewed current scientific literature, include that using neonicotinoids as a prophylactic is incompatible with the sustainable use of pesticides.

The following researchers gave their take on the report.

 

Dr. May R. Berenbaum, Professor and Head of Department of Entomology, University of Illinois at Urbana-Champaign (webpage):

Expertise: Elucidating chemical mechanisms underlying interactions between insects and their hostplants, including detoxification of natural and synthetic chemicals, and applying ecological principles in developing sustainable management practices for natural and agricultural communities. 

“The report is a great summary of recent literature and the authors are to be commended on the nuanced interpretation of the literature. Although I’m not intimately familiar with EU agricultural policy, in the context of the goal of sustainability (shared with the U.S.) their conclusion that ‘current practice of prophylactic use of neonicotinoids is inconsistent with the basic principles of integrated pest management’ really resonates.

“The use of the neurotoxic water-soluble neonicotinoids prophylactically, i.e., in the absence of evidence of an actual pest insect presence, makes no ecological, evolutionary, or even economic sense (as evidenced in the thorough literature review). I wish, though, that the group had not relegated ‘as well as other pesticides’ to a parenthetical phrase in their conclusions; I expect the same report could have been written under a different set of historical circumstances about any systemic water-soluble neurotoxic pesticide used to the exclusion of almost any other pest management method. To me this is the most important message and, in contrast with knee-jerk ‘ban the neonics’ responses, can keep us from making the same mistake again and again.”

 

Dr. Cynthia Scott-Dupree, Professor in the School of Environmental Sciences, University of Guelph (webpage):

Expertise: Integrated management of insect pests of crops; insect resistance to insecticides; integrated resistance management; biological control; impact of agroecosystems on non-target beneficial arthropods in field and greenhouse environments.

“I have read through the recently released report by EASAC entitled “Ecosystems services, agroecosystems and neonicotinoids” and feel that it presents an extremely unbalanced perspective focusing on crop protection and specifically neonicotinoids as the primary causes for global declines in biodiversity. The report suggests that declines in bird and beneficial arthropod populations are a result of the aforementioned stressors yet no causal relationship is shown, and in fact the authors of the report themselves indicate there is no causality.

“It is unfortunate that the conclusions of this report are based primarily on lab data that has little or no practical relationship to realistic field situations. Why can’t someone or some group prepare a balanced and holistic review of the scientific information on this topic that is not influenced by politics and emotion? We must try harder to establish policy for the longterm based singularly on a strong foundation of science.”

 

Dr. David Inouye, Professor Emeritus, Department of Biology, University of Maryland (webpage):

Expertise: Inouye has worked with bumble bees, euglossine bees, pollinating flies, tephritid flies, hummingbirds, and wildflowers, on topics including pollination biology, flowering phenology, plant demography, and plant-animal interactions such as ant-plant mutualisms, nectar robbing, and seed predation.

“The effects on pollinators (other than honey bees and bumble bees) and organisms that contribute to natural pest control and soil functioning have rarely been addressed in research so far, but acute lethal or sublethal effects have been observed on several natural pest control species such as insects and birds, and soil dwelling species such as earthworms. Thus neonicotinoids appear to have many of the same detrimental features that previous generations of pesticides, starting with DDT, have ultimately been found to have.

“The report specifically addresses the issue of integrated pest management, and concludes that for a variety of reasons IPM appears to be incompatible with the prophylactic use of neonicotinoids in coated seeds.  One of the major concerns is that only a small proportion of the insecticide enters the plant and most is released into the environment immediately, where it may have a variety of unintended consequences.

“As we learn more about the unintended consequences of releasing neonicotinoids into the environment it is becoming clear that there can be significant undesirable effects, such as those recently shown for aquatic organisms. The report concluded that ‘The effect that neonicotinoids might have on constraints to the restoration of biodiversity on farmland (one of the priorities of European agricultural policy) has been completely neglected.’ So although we can’t make a definitive pronouncement about the consequences for restoration of biodiversity, it seems likely that future studies will document negative effects.”

 

Dr. David Andow, Distinguished McKnight University Professor, Insect Ecology, University of Minnesota (webpage):

Expertise: Ecological risk assessment of biological stressors, such as invasive species and genetically engineered organisms, insect resistance management, gene flow and its consequences, and non-target species effects.

“I think the study is even-handed, and the conclusions are justified.  In context, the value of pollination is still generally undervalued, and controversies are around exactly how to measure the value.  While it is relatively easy to estimate what the value of pollination is, estimating the value of a 5% decrease in pollination by honeybees, is considerably harder, because the bee density-pollination value function is not linear.  In any event, because of historical undervaluation of pollination value, I believe the report makes an important adjustment to bring these valuations more in line with what is actually occurring.

“The amount of evidence is not great about neonics and non-honey bees, but the evidence that non-honey bees are important is well supported.  Thus the conclusion is based on sound inference, and only partially on sound evidence. By only partially, I do not mean that the evidence is contradictory, only that there is not as much as would be needed to base the conclusion purely on empirical findings.”

 

Dr. Joseph Morse, Professor of Entomology (webpage); Dr Elizabeth E Grafton-Cardwell, Research Entomologist and Director of Lindcove Research and Extension Center (webpage); Dr Frank Byrne, Assistant Researcher of Entomology (webpage), Department of Entomology, University of California, Riverside

Expertise: Integrated pest management and use of neonicotinoids in citrus.

“The report is quite interesting and it appears to be a solid and well-considered review. One of the overriding impressions we get from the review is the major impact that agriculture has on declining landscape heterogeneity and the consequences for species diversity. The use of pesticides is just one of the many layers that is required in efforts to sustain current levels of agricultural intensification that leads to the loss of natural habitat to agriculture. The review is quite comprehensive and gives good background to all topics discussed, making it easy to read and interpret. It is a review and considers available data in a well-rounded and unbiased manner, without questioning the validity of any study.

“There are several key points we noted in the review:

  • It appears to focus a great deal on the use of neonicotinoids as seed treatments. Use as soil treatments and foliar treatments are also mentioned but the focus is largely on seed treatments.
  • The focus of recent studies has largely been honey bees and there needs to be additional studies on other pollinators, natural enemies, and impacts on soil-borne organisms. Some field studies with honeybees have failed to show detectable effects of neonicotinoids on colony survival at field exposure levels. We can’t disagree with either of these statements.
  • There has been an increase in fertilizer use in Europe. In addition to increasing crop yield, this also appears to result in a strong decline in species diversity and flower richness within managed fields. This also makes sense.
  • Overall, there does not appear to be a proof of causality between increased pesticide use (we believe the intent here is neonicotinoid use) and a reduction in ecosystem services.
  • Prophylactic use of neonicotinoids is inconsistent with the basic principles of IPM. This is certainly true — it is a major premise of IPM that prophylactic use of any pesticides is not wise.

“We agree more studies are needed to optimize positive uses and minimize negative impacts. As stated in the European report, there are too many generalizations being made by the popular press and the public and more studies are needed beyond the current focus, which is largely on honey bees. One of the key issues for researchers to consider is the relevance of the exposure levels they are using in their studies. Neonicotinoids are insecticides, and will therefore kill, or disrupt the behavior of honey bees and other pollinators if the doses are high enough. Using field-relevant concentrations of the insecticides should be a priority, as this will give a true measure of the impact of these insecticides.”

For more detailed comments from Drs. Byrne, Grafton-Cardwell, and Morse on the use of neonicotinoids on citrus in California, its impact on honey bees and compatibility with integrated pest management please see this document.

 

Reference:

Ecosystem services, agriculture and neonicotinoids‘ published by the European Academies Science Advisory Council, Wednesday 8 April 2015.

 

Declared interests (see GENeS register of interests policy):

None declared.

Please feel free to leave your comments below, but be aware that by doing so you agree to our Terms & Conditions.