To bee or … no bees

Bees are vital for crop pollination (Photo: Jon Sullivan)

Bees are vital for crop pollination (Photo: Jon Sullivan)

No bees – a starving world, it’s as simple as that. Bees and other pollinators fertilise three-quarters of global food crops and have seen severe declines in recent decades, due to loss of habitat, disease and harmful pesticides. In the UK, wild honey bees are nearly extinct, solitary bees are declining in more than half the areas studied and some species of bumblebee have been lost altogether.

The large bee losses reported worldwide over the last decades have stimulated a lot of research on the monitoring of bees and the potential causes of the losses including pathogens, pests, diseases, nutrition, pesticides, habitat and climate changes. During this process, extensive datasets have been generated and collated on honeybee losses that have been linked to diseases, pests and pathogens in Europe and North America. Less is known about the situation for solitary bees and bumblebees.

Neonicotinoids part of the problem

A series of high-profile scientific studies has linked neonicotinoids – the world’s most widely used insecticides – to huge losses in the number of queen bees produced and big rises in the number of  bees that get lost and fail to return from foraging trips.

In 2012, several independent peer-reviewed studies were published showing that neonicotinoids had previously undetected routes of exposure affecting bees including through dust, pollen, and nectar and that sub-nanogram toxicity resulted in failure to return to the hive without immediate lethality. They also indicated environmental persistence of neonicotinoids in irrigation channels and soil. More than 30 separate scientific studies have found a link between the neonicotinoids, which attack insects’ nerve systems, and falling bee numbers.

In January 2013, the European Food Safety Authority (EFSA) published opinions that concluded that three neonicotinoids – thiamethoxam, clothianidin and imidacloprid – posed unacceptable risks to bees. In April 2013, the European Commission initiated enforcement of the world’s first continent-wide ban on the use of the three pesticides for two years on flowering crops such as corn, oilseed rape and sunflowers, upon which bees feed.

Europe should be commended for this action, but of course it was not universally praised. The chemical industry warned that a ban on neonicotinoids would lead to the return of older, more harmful pesticides and crop losses. Environmental campaigners pointed out that this didn’t happen during temporary suspensions in France, Italy and Germany and that the use of natural pest predators and crop rotation can tackle problems.

Scientists met to discuss solutions

Bumblebees pollinate tomato plants in an Icelandic glasshouse (Photo: Author)

Bumblebees pollinate tomato plants in an Icelandic glasshouse (Photo: Author)

Given the importance of all bee pollinators – not only honeybees ­- and the universally agreed multifactorial origin of bee losses, a more cohesive system for international protection of bees is considered necessary to ensure bee diversity, crop pollination and honey production at a global level. To this end, EFSA organised a Scientific Colloquium in May 2013 entitled ‘Towards holistic approaches to the risk assessment of multiple stressors in bees’. Over 100 international scientists attended the meeting from a broad range of disciplines such as ecology, biodiversity conservation, pollination, epidemiology, ecotoxicology and mathematical modelling.

The meeting concluded that current regulatory tests to assess risks in bees do not consider multiple exposures and combined effects of stressors, whether additive or synergistic. It was suggested that the use of predictive mathematical models might overcome the complexity of assessing multiple exposures. In addition, these tests focus on honeybees, but the use of honeybees as surrogates for other pollinator species is questionable because these have different life cycles, routes of exposure and sensitivity to stressors.

The bee experts also urged the rapid implementation of expanded protocols for field tests of pesticides to increase their statistical power and ecological relevance. The tests should be standardised and validated and include assessment of sub-lethal and chronic effects on individual bees, colonies and populations.

Overall it became obvious that more research is required for bumblebees and solitary bees including basic knowledge of the biology and ecology to more specific knowledge on the genomics, abundance and distribution of species through wide scale monitoring programmes.

Finally, it was clear at the colloquium that effective communication and information flow among scientists, beekeepers, farmers, decision makers and other parties is essential, not only for risk assessment and management purposes, but also to ensure that appropriate research is conducted and communicated.

Laggards might think again

The US Environment Protection Authority has advised that it is re-reviewing the use of neonicotinoids but, taking into account the information available to date, the best management practices that have been initiated, and the benefits that this class of chemicals affords, it considers that action similar to the restrictions introduced in Europe is not warranted in the USA at this time.

Some countries like Australia don’t even think they have a problem yet. If that is due to lack of research and large knowledge gaps it might be time to consider appropriate action before it is too late as suggested in a recent publication.

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