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Neonicotinoids, bees, ecosystem services and agriculture

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Context - Neonicotinoid pesticides have been on the forefront of a controversy in the last few years on the effect that they might be having on honey bees. Do they have an effect on other parts of ecosystems and on the services they provide?

Do neonicotinoid pesticides have an effect on services provided by ecosystems?

This is a faithful summary of the leading report produced in 2015 by European Academies' Science Advisory Council (EASAC): "Ecosystem services, agriculture and neonicotinoids " 

  • Source document:EASAC (2015)
  • Summary & Details: GreenFacts

Introduction

Pollination is just one of several ecosystem services of importance to agriculture and our society. Therefore EASAC decided to conduct a study on neonicotinoids not only considering their effects on honey bees but also from the wider perspective of their interactions with agriculture and ecosystem services. This study has not only reviewed the science available to the EFSA but also over 100 new peer-reviewed studies that have emerged since the European Food Safety Agency (EFSA) review in 2012.

Why is there a concern about the impact of Neonicotinoid pesticides on the environment?

Neonicotinoid pesticides have been on the forefront of a controversy in the last few years on the effect that they might be having on honey bees. In light of the available evidence, the European Commission restricted some of their use in 2013.

One of the main services provided by bees is the pollination of crops, and it is one that is critical to agriculture, as up to 75% of the crops traded on the global market depend to some degree on pollinators. But there are many other services provided by ecosystems that are important for the functionning of agriculture. This report examines the effect that neonicotinoids might be having on those other environmental services.

What are ecosystem services?

Nature provides human society with a vast diversity of benefits such as food, fibre, clean water, healthy soil and carbon capture, and our well-being is totally dependent upon the continued flow of these ‘ecosystem services’.

Ecosystem services are the various benefits that are provided by ecosystems, whether they are in their natural state or are actively managed and modified by humans. These services represent a massive contribution to the economic well-being of all societies.

Agricultural -ecosystems are highly managed and simplified, compared to natural ecosystems, but they still function essentially in the same way and depend on several of the services provided by nature. Such key ecosystem services are pollination, natural pest control, maintenance of soil fertility and farmland biodiversity and its supporting habitats.

What is the present state of honey bee colonies and other pollinators?

Surveys of managed honey bees throughout Europe over the 1985–2005 period, show that colony numbers have increased in 26 countries (up to a doubling) while they had declined (up to 47%) in 15 countries. Protecting honey bees is not sufficient to protect pollination services and other ecosystem services. In the case of wild bee species, of other pollinators (bumble bee, buttezrfly, moth), of insect species with natural pest control functions and of biodiversity indicators such as farmland birds, all show major declines in recent decades. As of now one of the causes of the decline of bees that has been clearly identified is the ectoparasitic mite (Varroa destructor), an invasive species from Asia has contributed to the loss of most wild and feral honey bee colonies in Europe. Another invasive species, the fungal pathogen Nosema ceranae, is also present in bees, infecting their gut. Such diseases are not necessarly separate causes since the possibility that bees become more sensitive to infections under the influence of pesticides is a potential confounding factor, and factors other than neonicotinoids can also be important potential contributing factors to the reported declines.

What are the effects of neonicotinoids?

The neonicotinoids are neurotoxins that specifically target insects and induces paralysis and death. Most neonicotinoids show much lower toxicity to mammals than to insects but they have an impact on non-target organisms: both invertebrates and vertebrates, and whether located in the field or on their margins, in soils or in the aquatic environment.

The use of neonicotinoids as it is currently done, is considered to be unlikely to directly kill bees, but it can have a negative impact on them and reduce their survival. It also has negative effects on other organisms, from birds to soil microorganisms. This is why the European Commission restricted the use of 3 neonicotinoids for seed treatment, soil application (granules) and treatment of leaves in crops attractive to bees and entirely banned non-professional use. Industry studies argue that their withdrawal would have serious economic and food security implications.

Should the EU regulation of neonicotinoids be changed?

The framework directive of the EU concerning the use of pesticides has at its core the principle of using pesticide in a sustainable way, and the use of neonicotinoids should be guided by the same principle.

Neonicotinoid insecticides raise several issues that the regulatory system did not initially sufficiently address and that are not yet resolved :

  • the high variability in persistence and spread to other parts of the environment,
  • the cumulative nature of the toxic effects even at low levels,
  • the mechanisms through which sublethal effects can affect functioning of individuals or entire colonies,
  • the differences between acute and chronic toxicity effects,
  • the toxic effects on beneficial insects,
  • synergistic effects with other neonicotinoids, pesticides and fungicides,
  • immune system interactions, and
  • wider ecosystem effects.

One source of contention on the regulatory process between stakeholders is how to balance the available evidence with the continued uncertainties in knowledge according to the precautionary principle. The question is thus raised as to what extent widespread use of the neonicotinoids is compatible with the objectives of sustainable agriculture, and this question should be examined further.


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