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Neonicotinoids, bees, ecosystem services and agriculture


    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. The European Commission restricted tehir use in 2013 in light of the evidence that certain uses of neonicotinoids could have a detrimental effect on honey bees.

      One of the main services provided by bees is the pollination of crops, and it is one that is critical to agriculture. But there are many other services provided by ecosystems that are important for the functionning of agriculture. Protecting honey bees is not sufficient to protect pollination services and other ecosystem services. 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 of are actively managed and modified by humans. These services represent a massive contribution to the economic well-being of all societies.

        They can be classifed in :

        • Provisioning services, which are the products obtained from ecosystems, such as lumber, food, and water
        • Regulating (and supporting) services, which are the ways that the environment keeps itself running, such as trough water purification, the natural regulation of pests, prevention of erosion, and of course, pollination.
        • Habitat services, such as the maintainance of the locations that migratory species need on their journey.
        • Cultural and amenity services, which is the enjoyment and fulfillment that we get from ecosystems, through anything from tourism to spiritual experiences, through inspiration for art and culture.

        Biodiversity is positively interlinked with the provision of ecosystem services, as well as being an objective in its own right, and adequate habitat management within crop has positive effects on the abundance of natural enemies of many pest species.

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

          Agricultural -ecosystems are highly managed and simplified, but they still function essentially as natural systems and depend on several of the services provided by nature. The key ecosystem services for these systems are pollination, natural pest control, maintenance of soil fertility and farmland biodiversity and its supporting habitats.

          Pollination is a service that involves flowering plants, arthropods, birds, mammals, as well as other invertebrates, fungi, protists and bacteria. The diversity of pollinators can improve crop yield or fruit quality. Worldwide, 75% of the crops traded on the global market, which contribute vital micronutrients (e.g. vitamins, folic acid) and dietary variety, depend to some degree on pollinators. Wild pollinating insects often pollinate crops more effectively than honey bees and are thus relevant for crop productivity.

          The monetary value of pollination services is one of the easiest ecosystem services to value, since it is simply the value of the crops that need pollination. In Europe , this is estimated to be €14.6 billion in fruits and vegetables produced. There is an emerging pollination deficit, in part because of the loss of some of the semi-natural landscape elements in farmland that are rich in flowers. As an alternative, urban areas and mass-flowering crops may provide important resources for bees.

          ‘Natural pest control’ through predation (by insects, birds, etc.) or parasitism (by parasitic wasps, some beetles, etc.) can keep pest populations at a level low enough as part of their natural behaviour to avoid the need for chemical measures. Pests can also be controlled or reduced by natural antagonists that move into the crop from the surrounding natural vegetation.

          A further key ecosystem service is the supply of mineral nutrients in the soil through the action of soil organisms. However, the extensive use of fertilisers, combined with the tillage and cultivation reduces the diversity and activity of soil biota further and contributes to carbon loss from soil, higher erosion risks, increased sensitivity to soil-borne diseases and losses of other services provided by agriculture soils.

          What are the effects of neonicotinoids?

            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. In the case of wild bee species, of other pollinators, of insect species with natural pest control functions and of biodiversity indicators such as farmland birds, all show major declines in recent decades. However, these assessments and comparisons between countries are limited by the fragmentary nature of many of the surveys and the lack of consistent standards for measurement.

            In the 2012-2013 winter, most southern countries in Europe experienced losses of bee colonies below 10%, whereas losses in northern countries were between 20% and 30% but it is unclear to what extent these represent confounding socio-economic factors such as the number of beekeepers. The rate of winter colony loss in the USA, which has been around 30% for most of the previous 12 years, and as of now the causes that have been clearly identified are 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.

            Should the EU regulation of neonicotinoids be changed?

              The insecticides applied to crops to kill insect pests could be part of the negative effects of agricultural intensification. An evaluation of the different factors, from changes in landscape to the use of insecticides, showed that the strongest associations were between the use of insecticides with the reduction in the natural potential for controlling pests, as well as with negative effects of birds, beetles and flowering plants. While there are statistical correlations, these are not proof of a causal link.

              The residues of insecticides end up in different parts of the plant, such as pollen and nectar, and can remain in the plant for long periods of time. Through that, insect species that are not the intended target can also be exposed, often for long periods of time. These chemicals can also pass to other parts of the food chain, for example when birds eat contaminated insects, or when soil microorganisms decompose treated plant matter.

                The neonicotinoids, a new class of synthetic chemicals which entered the pesticide market since 1990, are neurotoxins that mimic the naturally present neurotransmitter acetylcholine, blocking the normal neural pathways in insects and so leading to paralysis and death. Due to diifferent mechanisms, most neonicotinoids show much lower toxicity to mammals than 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.

                Most toxicity testing has been conducted on honey bees, which may not be useful for predicting effects on other bees or other pollinating insects. Additionally, there seems to be synergistic effects between different pesticides (for instance when bees are exposed to neonicotinoids and fongicides at the same time) and also with some bee parasites and viruses. The response of the immune system of bees might be limited after exposure to neonicotinoids, allowing infections to take hold. Such effects reduce honey bee survival and increase developmental deformities.

                One neonicotinoid, at least when used to treat oilseed rape and cotton seeds, can enter the food supply of birds. Neonicotinoids can also have a negative effect on soil organisms and a correlation was found between the abundance of aquatic macroinvertebrate species and nearby concentrations of a neonicotinoid.

                The protective – or « prophylactic » – treatment of seeds has negative impacts on non-target organisms, and is inconsistent with integrated pest management, and the widespread use of pesticides constraints the potential for restoring biodiversity in farmland. 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 argued that their withdrawal would have serious economic and food security implications.

                  Many aspects need to be taken into account when evaluating the degree of risk :

                  • the nature of the effect being considered (individual or colony)
                  • the species of pollinator;
                  • the nature of the insecticide use;
                  • the extent to which actual application follows or does not follow the manufacturers’instructions;
                  • and other factors.

                  When all of these factors are taken into account, including the modification of planting equipment to limit exposure to treated seeds, it is considered that the use of neonicotinoids is unlikely to cause direct mortality of bees. However, protecting honey bees is not sufficient to protect pollination services or the other ecosystem services that have been examined, as other bees or pollinators are likely to be more sensitive to losses.

                    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.

                    However, neonicotinoid insecticides raise several issues that the regulatory system did not initially sufficiently address an 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 or not with the objectives of sustainable agriculture, and this question should be examined further.

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