Swarm enemies: pesticides, disease and the future of bees

The honeybee, and bees in general, have been having a very difficult time in recent years. Their plight and the various threats that have put them in peril have been the subject of widespread media coverage over the past decade, and never more so than now. The countryside has become far less bee-friendly thanks to the degradation of suitable forage habitat and reduction in the overall size of forage areas since the end of the second world war. Yet this is nothing compared to the threat from a tiny but hugely destructive mite, and from the species that relies on bees the most: humans. The announcement last week that the US Court of Appeal had overturned a decision by the US Environmental Agency to approve the pesticide, sulfoxaflor, is the latest in a continuing battle over the use of a highly controversial group of “bee-harming” pesticides in agriculture.

If habitat loss and degradation has reduced opportunities for bees, the parasitic mite varroa destructor has had a pronounced effect on the beekeeping industry and wild honeybees. Varroa mites weaken the bee by attaching themselves to the body and sucking hemolymph (the fluid similar to blood in mammals) from their host. In doing so the mite causes the parasitic disease varroosis and passes on other diseases such as deformed wing virus.

Despite the introduction of chemical controls, the European honeybee (Apis mellifera) is essentially defenceless against varroa mites, which in the past 50 years have spread from Japan through eastern Europe, arriving in the UK in 1992, having appeared in the US five years earlier. Australia remains free of the mite and there are Russian bees with greater resistance, along with a subspecies of bee discovered in Libya in 2010 that is reputedly mite-free. But in countries where varroa is present, wild bee populations are extremely rare, with honeybee populations thriving only when they are actively managed.

Neonicotinoid pesticides, of which sulfoxaflor is one of a subgroup, have been closely linked with the decline in bee populations, resulting in an EU-wide moratorium on their use being introduced in 2013. The evidence on which the moratorium is based has been hotly contested by the big agrochemical companies, and backed with equal robustness by invertebrate and conservation experts. Field studies into the impact of chemicals on honeybee and bumblebee populations are notoriously difficult to conduct because of the mobility of the bees and the quantity of neonicotinoids already present in the environment. This apparent analytical uncertainty has proved to be the battleground between the opposing sides.

This summer the UK government, responding to a request from the National Farmers Union (NFU), agreed to a partial overturning of the moratorium, allowing the use of enough neonicotinoid-treated seeds to grow 5 per cent of oil seed rape production in the UK.

The study used by the UK government to sanction the reintroduction of neonicotinoids is, critics say, deeply flawed. They argue that, having failed in their attempt to collate field data, scientists from the UK’s Food and Environment Research Agency (Fera) misread the complex statistical data analysis they then employed to see whether there was a connection between reduced numbers of queen bees and the presence of neonicotinoids.

It is not just conservationists who are calling the Fera study into question; the European Food Safety Authority discounted the entire report when it made its recommendation to the EU that the threat to bee health posed by neonicotinoids was “unacceptable”.

The NFU requested a partial overturning of the moratorium because of “widespread crop losses of oilseed rape crops due to infestation by cabbage stem flea beetles”. But the numbers simply do not stack up — UK farmers are reporting oil seed rape yields of 3 per cent to 9 per cent higher than the 10-year average. The invertebrate conservation charity Buglife has pointed out that the yield rise may well be an early sign that the neonicotinoid ban is showing benefits, and is a result of subsequent improved pollination from bees.

In a move that has helped to fuel conspiracy theories, the UK government ordered that the minutes of the Expert Committee on Pesticides, at which recent “selective reintroduction” of neonicotinoids was agreed, should be withheld.

As much as the government might like the neonicotinoid debate to remain under the radar, an online petition against neonicotinoids, organised by the campaigning website 38 Degrees, has already attracted more than half a million signatures in the UK. Adding to the pressure, Friends of the Earth has filed a High Court challenge to have the decision to reintroduce neonicotinoids declared unlawful. We can expect the parliamentary return from summer recess to be dominated by bees.

It is little wonder that as honeybees have declined and the threats against them have piled up, interest in beekeeping has increased. Membership of the British Beekeepers Association grew from 11,000 in 2008 to more than 23,000 by 2013, and much of the growth is attributed to increased concern about the plight of bees. However, despite the recent upsurge, in the long term there has been a net reduction in the number of beekeepers, looking after a reduced number of hives. There are now an estimated 44,000 beekeepers in the UK, tending 135,000 hives — 60 years ago there were about 300,000 hives. Each colony comprises approximately 20,000 individual bees, producing 16kg of honey per season.

The total global economic value of bees is incalculable: UK estimates range from about £200m a year for commercially grown, insect-pollinated crops, to more than £500m added to the wider economy in the form of bee products — honey and beeswax. About 70 crops in the UK are dependent on, or benefit from, visits by bees.

While the number of beekeepers and hives has declined overall, there has been a significant increase in city beekeeping in the past decade. Among these new urban beekeepers are some high-profile exponents. Since 2008 there have been bees on the roof at Fortnum & Mason’s flagship Piccadilly department store. Tastefully housed in English oak hives painted in Fortnum’s signature eau de nil, the structures are topped with gold leaf-covered finials. The colony grows to about 50,000 in summer, with bees flying up to three miles to forage.

There are also hives on the roof of the London Stock Exchange, with 100,000 bees, inspired by LSE chief executive Xavier Rolet, who has beehives on his estate in south-west France. Japanese investment bank Nomura has had two hives on the roof of its London office since 2011.

New York, too, has a thriving bee scene, with a dedicated Honey Week in September. Beekeeping in the city was legalised only in 2010, but already there are more than 260 hives, leading to concerns about their long-term viability. A colony requires about an acre of foraging space to survive, but in cities suitable habitats can be densely congested in areas with flower-filled parks and gardens, but completely absent in places where concrete, tarmac and closely mown grass are the norm.

The number of hives in London doubled between 2008 and 2013, from 1,677 to more than 3,500, resulting in a hive density of about 10 per sq km. In the rest of England and Wales the density is 0.9 hives per sq km.

The worry, as one expert puts it, is that to increase bee populations in areas where foraging competition is high is like putting an endangered grazing animal in an overgrazed savannah.

The hives at Fortnum & Mason and the LSE serve a noble purpose, introducing bees to a city environment where they otherwise might not exist. But the solution to the species’ long-term survival must surely lie in balanced bee populations in urban and rural environments, with the protection they deserve afforded to them, based on good, irrefutable science.

Bee-friendly gardens

Gardens, by default, are reasonably bee-friendly habitats. But some are definitely friendlier than others. The key ingredient for honey and solitary bees is pollen- and nectar-rich flowering plants, over as long a season as possible.

Plants with tubular flowers, such as Verbena bonariensis, agastache, salvia and buddleja, are particularly attractive to bees, and they will busily dip their probosces in to get to the nectar. Agastache in particular is something of a wonder perennial, with weatherproof flowers that keep going through summer into early autumn. Verbena has an added benefit of being a great all-round wildlife plant.

Flowering trees are as important as perennials. Malus (both ornamental and culinary forms) are a key food source, and later in the season lime trees (Tilia) positively vibrate with bees foraging through the flowers.

Fresh water is a must: bees will congregate on anything from a bird bath to the banks of a stream or lake.

Wild-flower meadows can provide a high-intensity hit of nectar in early summer, and are the kind of undisturbed habitat that is perfect for solitary bees to nest in.

The foot of a native hedgerow is another excellent nesting habitat, especially if flowering wild hedge shrubs such as hawthorn (Crataegus monogyna), dog rose (Rosa canina) and blackthorn (Prunus spinosa) are present. Sowings of annual meadow flowers and agricultural “green manure” plants such as Phacelia tanacetifolia are an excellent way of providing large-scale forage.

Although honeybees are dormant during winter, solitary bees, especially bumblebees, will often fly on sunny, still days at any time of year. Winter flowering plants such as Viburnum x bodnantense and Chimonanthus praecox (wintersweet) are the ideal out-of-season food source.

Less manicured gardens will always be more bee-friendly than those pampered to the nth degree.

A little mess can be a good thing.

Matthew Wilson is managing director of Clifton Nurseries, London

Photographs: Alamy; Getty Images/Flickr RM; Redux/Eyevine; AFP/Getty; Robert Mabic/GAP Photos

Letter in response to this article:

Bees’ decline is disastrous for natural environment / From Elizabeth Mortimer