Chemical that protects roses from disease damages the insects’ muscles

  • Chemical Myclobutanil, used to protect roses, is found to damage bees’ muscles
  • The fungicide had been recommended by the Royal Horticultural Society
  • But now a new study has found it could imperil bees ability to find food 


Gardeners who spray their roses with a common fungicide could be harming bees.

A chemical used to protect roses from black rot and powdery mildew has been found to damage bees’ muscles, making them less able to complete long foraging flights or keep warm in winter.

While banned pesticides used by farmers were known to be toxic to bees, there are fewer studies on fungicides used by ordinary families.


Myclobutanil is a common fungicide but could be deadly for bees’ chances of surviving winter

Myclobutanil is recommended by the Royal Horticultural Society to stop the powdery mildew which affects ornamental plants. In roses it forms a white fungal growth on plants, causing flower buds to fail to open properly.

But the commonly used fungicide has been found to react badly with a naturally-occurring chemical in plants which bees also ingest.

Together, scientists at the University of Illinois found, the substances damage the thoracic muscle honey bees need to sustain lengthy flights and which they vibrate to generate heat of up to 35C to keep the rest of their colony warm in freezing temperatures.

The authors, led by Dr. Wenfo Mao, conclude that Myclobutanil, also used by farmers, put bees ‘at risk of being unable to extract sufficient energy from their natural food’.

Dr. Ivor Davis, former president of the British Beekeepers Association, said: ‘We would like to encourage more gardeners not to use pesticides and fungicides unless they absolutely sure they are bee-friendly.

‘In the winter bees have to keep warm by flexing their muscles and if they can’t, they die earlier than they should, the colony does not build up as it should and in some cases may even collapse.

‘Gardeners do have a responsibility, as farmers do, because in urban areas bees will forage more in people’s gardens than they will in fields.’

Myclobutanil is an approved fungicide across the EU, although the chemical is not contained in sprays for domestic crops, only flowers. The RHS recommends it to control rust, black spot and powdery mildew on roses, as well as rust and powdery mildew on ornamentals.

The US researchers found that combined with quercetin, a chemical found in plants which bees feed on, worker bees exposed to Myclobutanil were at risk of losing their ability to fly long distances.


Research found that the fungicide lowers the energy levels for the bees’ flight muscles.

These insects had lower levels of adenosine triphosphate – the energy source which fuels their flight muscles.

Just as food and drugs work together to harm the human body, fungicides work with compounds found in plants to alter honey bees’ physiology. Experts say this may also apply to bumblebees, whose bodies work very similarly.

Dr. Richard Comont, science manager at the Bumblebee Conservation Trust, said: ‘This study demonstrates the potential harm which can result from using even apparently innocuous chemicals on our gardens and beyond.

‘It is very likely this mechanism also works on our wild bees, so using as few pesticides as possible is key to bees’ survival.’

Neonicotinoids previously used by farmers, and found to stop bees buzzing to release pollen, are now banned in the UK. However, experts say they are still used by some gardeners. While the EU has ruled to stop products with high residues of Myclobutanil being sold, it too is also still on the market.

Dr. Davis called for gardeners to take further steps to help bees at this time of year by using their gardens to provide plants rich in pollen and nectar.

Crocuses and snowdrops provide copious nectar, which gives bees their carbohydrates, while willow trees are an important source of floral pollen, providing protein.

Curated from: dailymail


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