GUEST BLOG: Bumblebees by Keith Heywood

This is the first Guest blog we have featured and it has been provided by Keith Heywood who has recently taken up an interest in ‘bumblebees’.  If you have any questions relating to the content of Keith’s piece then I’m sure he’d be happy to provide a response, his contact details can be found at the bottom of the post.
The Red-tailed Bumblebee Bombus lapidarius
Red-tailed Bumblebee.  Image: Keith Heywood.

There has been a lot of publicity about Honeybees recently, in this blog and elsewhere especially in regard to neonicotinoids. It has not fallen on deaf ears. But we should remember that Honeybees, important as they are, are only one of many insect pollinators. Even within bees, in the UK there are around 270 species of bee, one species of Honeybee, 25 bumblebees – the rest are solitary bees.

In 1985 Dr Roland De Jonghe discovered that a nest of Buff-tailed bumblebees placed in a greenhouse containing tomatoes very effectively pollinated them, by buzz fertilisation – and realised that there was the potential to supersede the then current method of manually fertilising flowers with a vibrating wand, a procedure that need to be repeated daily throughout the growing season. The quest was then on to find a way of producing bumblebee nests on a commercial scale.

A Bumblebee nest is only occupied for a single season, as soon as the new queens and males are produced the nest winds down, as no new eggs are laid. The newly fertilised queens then seek a site to hibernate over the winter. Scientists had gradually discovered how to keep a nest in captivity at controlled temperature and humidity, so that the fertilised queens could be “harvested” and kept in cold storage until the next year. It was all very labour intensive and expensive. In 1987 De Jonge started a company to produce nests commercially, and within 2 years they were exporting to Holland and the UK. Other companies swiftly followed, methods improved and costs came down. Now there are over 30 factories in Europe, many in Turkey, exporting a million nests worldwide, mainly for tomato and pepper fertilisation, but also increasingly for crops such as strawberries and raspberries which are grown in open-ended polytunnels..

This is clearly good for agribusiness, but is it also good environmentally? On the negative side is a high carbon footprint resulting from the high energy requirements of the breeding units and distribution of the nests. The nests themselves consist of a plastic inner box, surrounded by polystyrene insulation and finally encased in a cardboard cover. The nests are non-recyclable and growers are encouraged to freeze them after use to destroy any remaining bees, but many incinerate them or simply throw them into a skip. More positively the growers are forced into using environmentally-friendly methods of pest control in order to protect their bees.

The industry is unregulated and the chance of diseases spreading in the “bee factories” is high given the humidity and temperature. Another source of infection is the food used – pollen, which is collected from Honeybees in large quantities – Honeybees and Bumblebees both suffer from several common diseases The species used is mainly the Buff-tailed bumblebee – Bombus terrestris. In Britain the Buff-tails belong to the endemic subspecies Bombus terrestris audax. In Turkey the local subspecies is Bombus terrestris dalmatinus, in France and Germany Bombus terrestris terrestris . Over 60,000 nests are imported into the UK annually. The chance of Bumblebee queens and males escaping into the surrounding environment must be reckoned. They interbreed freely with the native subspecies and the resulting hybrids are fertile. The subspecies which developed in the UK is therefore being genetically modified, as well as being subjected to imported diseases.

A recent study “Disease associations between honeybees and bumblebees as a threat to wild pollinators” was published in the February 2014 issue of “Nature” concludes that diseases spread by commercial honeybees are instrumental in the decline of bumblebees. A summary of the main findings was published in the Guardian and a podcast (Plight of the bumblebees) is available on the Nature website.

Bumblebees have been recorded in the UK for a long time, the first distribution maps being produced by Frederick Sladen a hundred years ago. More recent distribution maps have shown a dramatic decline in most species. However what has never been recorded is population density. It is much more useful to be able to detect variations in population density than a simple present/not present measure. Two years ago the Bumblebee Conservation Trust (BBCT) started a project called Beewalk to define transects throughout the country, and to monitor these monthly from March to October, counting the number of individuals seen for each species.

bumblee-discovery

The BBCT are trying to recruit as many participants as possible who can commit to setting up a transact and to walk it each month (taking about an hour). Data is then entered online in a simple process. Having attended a workshop at Haggs Wood, Escrick last weekend, where 8 species were found in the practical session after lunch a walk from Jones Cable on to Thorne Moors will be defined, and we look forward to sharing the results in due course.

Another example of citizen science is the Big Bumblebee Discovery, a project observing the diversity of bumblebees across the UK this summer will be run by Dr Helen Roy and Dr Michael Pocock from the Centre for Ecology & Hydrology.

A very good, and very readable, book on bumblebees is A Sting in the Tale: by Dave Goulson, the founder of BBCT. It was shortlisted for the Samuel Johnson non-fiction prize last year.

The National History Museum publish a useful identification guide and finally http://www.bumblebee.org/is a mine of useful information.

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