'Unnecessary' weedkillers could undermine efforts to protect bee population

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Gardeners and flower lovers are being warned over the dangers posed to bees from pesticides and weed killers

New research encouraging gardeners to increase bumblebee populations by planting flowers could be undermined by the use of weedkillers and pesticides, Bumblebee Conservation Trust (BBCT) warns

The Bumblebee Conservation Trust (BBCT) has cautioned that harsh chemicals could further harm bee populations and said that weedkillers are not ‘necessary’ in garden settings.

Concerns were raised as a study published this week found horticulturalists and gardeners could increase bumblebee numbers by growing red flowering plants and flowers with stripes along the veins.

There are 25 different species of bees in the UK, but the bumblebee is the most important pollinator for crop production - and farmers are being told to make agriculture more pollinator-friendly.

‘The use of weedkillers greatly reduces the number of wildflowers and in nearby hedgerows, and that is obviously indirectly harmful to bees. In farming, we need to use the least harmful pesticides and to use them as carefully as possible,’ said BBCT Chair, Dave Goulson. ‘Bumblebees are the most abundant and also the largest wild pollinators in most of Europe, and are responsible for pollinating many hundreds of wildflower species and many crops such as raspberries, strawberries and runner beans.’

The study by scientists from the UK and New Zealand focused on the snapdragon as the bumblebee’s weight can open the plant’s closed flower. By analysing foraging patterns, the study found that plants with red flowers or venation patterns attracted more bumblebees. It compared the number of visits made to the snapdragon to the number of visits made to other plants, as well as the number of flowers visited per plant.

‘Bumblebees have declined because of reduced numbers of flowers. Gardens cover one million hectares of the UK, so if they all contained bee-friendly flowers then it would make a real difference,’ Goulson said.

European Pesticide Legislation has already led to the removal of a number of more environmentally damaging pesticides and all existing pesticides used in Europe are being re-evaluated. Insecticides contaminate pollen and nectar sources and can affect bees inadvertently bringing the chemicals back to their hives.

'Pollinators such as bees are of immense importance to agriculture and it is important to ensure bees have good sources of pollen and nectar when they are establishing nests. Many chemicals naturally derived from plants have potential uses within crop protection as they are biodegradable and have no long term environmental effects,’ Dr Ian Bedford, Head of Entomology at the John Innes Centre, told The Ecologist. ‘Other alternatives include surfactant based products that create a sticky environment around delicate pest species like whiteflies. Bees are not affected by this.’

There are now alternatives to conventional weed killers such as ascetic acid weed killers, fatty acid weedkillers and salt weed killers.

For a list of alternative organic weedkillers see: http://www.weed-killer.org/organic-weedkiller-recipes/

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