On Saturday I helped out with the food at a seminar held by the Ealing & Harrow beekeeping associations. Baklava went down very well with the beekeepers, even though I cheated and used Cornish honey rather than Greek. Here’s a few notes I took from one of the talks by the brilliant Dr Juliet Osborne…

Dr Juliet Osborne, Dept of Plant & Invertebrate Ecology, Rothamstead Research Institute. ‘Honeybees & Bumblebees – what is happening to them?’

Pollination value

87 of the world’s crop species require bee pollination to some extent – 35% of global food production (Klein et al, 2007). These species include most fruit crops (especially orchard fruits), salad crops (e.g. courgettes, peppers, tomatoes etc), seed & oil crops (sunflower, rape, beans) and some crops which may surprise people (coffee, cocoa). It’s hard to estimate the value of bee & insect pollination to the UK crop market, but estimates vary from between £200m-430m.

Are bees dying out?

Because there have been many stories on Colony Collapse Disorder and disappearing bees in the media over the last couple of years, many people have the impression that honey bees are dying out or at least reducing in number. In fact the situation is more complicated that that. A recent study by Aizen & Harder (2009) found that globally, honey bee stocks are actually increasing (see abstract: http://www.cell.com/current-biol…. However they also found that we’re becoming more dependent on crops that depend on animal pollination, which may cause problems with global pollination capacity.

In some places honey bees have indeed declined – the UK, USA, USSR, Germany. But in others stocks have risen – China, Argentina, Spain. There have been no reports of high colony losses in the Southern hemisphere – South America, Africa, Australia – which are areas with either no or lower varroa levels. There is some evidence that high losses are perhaps associated with varroa & its associated viruses. Promising anti-varroa discoveries have been made recently, so hopefully in the future we might be able to better control it.

Dr Osborne’s work…

Bees have a variety of stresses in their lives, both inside the hive (e.g. beekeeper’s interventions, varroa mites, disease) and outside (e.g. pesticides, bad weather, lack of available forage). Dr Osborne and her team are currently carrying out a three year project looking at how these inside and outside factors combine to affect bees. They track foraging bees using tiny 16mm aerials which only weigh 3mg. When the forager arrives back at the hive they remove the aerial so she doesn’t get stuck inside!

The team are only into the first year of their project but have already made some interesting discoveries from their radar data. Having radar tracked the first orientation flights of young bees, they found that bumblebees start by doing complex loops and only do 1-3 practice flights before starting foraging. In contrast, honey bees do very simple loops and take up to 18 practice flights before foraging. It may be that honey bees follow waggle dances even in their first flights, explaining the ‘there and back’ simple loops.

Bumblebees are important too…

Sadly, in the UK most bumblebee species have decreased in range and one may be extinct. Many species are now only present in the West country, South East and Norfolk. There are about 23 species of bumblebees in the UK, six of which are common. Bumblebees don’t store honey, so they are very vulnerable in spring to changes in the weather, although they can forage in cooler temperatures than honey bees. They need plenty of food and undisturbed nesting sites, having a particular preference for vacated small animal nests. Some nest underground in shortish turf; the most vulnerable are the surface nesters, whose nest will be destroyed by any management of the turf.

We have one newcomer here, the handsome ‘tree bumblebee’, Bombus hypnorum. It was first seen in 2001 near Southampton and has since spread rapidly northwards. It loves living in bird nest boxes and can unfortunately be quite aggressive compared with our native species, sometimes stinging without provocation. A pic of Bombus Hypnorum (see more on the BWARS Bees, Wasps & Ants Recording Society website):

Dr Osbourne reminded us that gardens are good habitats for bumbles. They like undisturbed, un-mown areas best, in tussocky grass. Old bird boxes and compost heaps are also good. In her opinion, the bumblebee bee boxes you can buy from garden centres just don’t work! So those of us with gardens should be letting them grow as wild and messy as possible if we want to encourage bees and other wildlife. As beekeepers we should be encouraging the public to keep any unwanted bumblebee nests in their gardens, and if they cannot be persuaded, try to move the nest to somewhere suitable. This is best done at night when most of the bumbles will have returned home.