There’s nothing quite like the gentle buzz of a bumblebee to let you know summer’s approaching.

But the distinct hum could soon become a rarity – as climate change is reducing the frequency and pitch of wing vibrations, according to scientists.

Experts warned this could have consequences for the effectiveness of bee communication and their role as pollinators.

And it could be bad news for the nation’s tomatoes, blueberries and honeysuckle plants.

A team from Uppsala University in Sweden analysed colonies of buff-tailed bumblebees – one of the most numerous bumblebee species in Europe and the UK.

They used accelerometers to measure the frequency and audible pitch of the bees’ buzz, specifically focusing on the sounds they make when they aren’t flying.

Analysis showed that bees were affected by both increased temperatures and exposure to heavy metals, with their muscles contracting less during buzzing.

This led to fewer wing vibrations at a reduced audible pitch – suggesting the buzz might not be so loud.

‘People have been long interested in how insect flight muscles work, as these muscles power the most efficient flight systems in nature,’ Dr Charlie Woodrow, one of the study’s authors, said.

‘However, many do not know that bees use these muscles for functions other than flight.’

These important non-flight muscle vibrations are used in communication, defence and buzz-pollination, he explained.

‘Buzz pollination is an incredible behaviour whereby a bee will curl its body around the pollen-concealing anthers of some flowers and contract the flight muscles up to 400 times per second to produce vibrations which shake the pollen loose,’ he said.

Many common garden plants rely on buzz pollination including tomatoes, blueberries and honeysuckle.

They said their findings could help to identify the species or regions most at risk.

‘Perhaps buzzes could even be used as a marker of stress or environmental change,’ Dr Woodrow said.

‘For example, we now know that certain environmental pollutants can affect the buzzes bees produce, so they could even serve as an indicator of ecosystem health.

‘If these vibrations are disrupted, this could lead to poor communication in the colony, inefficient thermoregulation, or poor resource acquisition for their offspring.’

A reduction in buzz pollination could also have potentially serious consequences for plant reproduction and biodiversity.

If the environment gets too warm then bees may simply choose to avoid buzz-pollinated flowers, Dr Woodrow explained.

The research was presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium.

WHAT IS THE HONEYBEE CRISIS?

Honeybees, both domestic and wild, are responsible for around 80 per cent of worldwide pollination, according to Greenpeace.

But bee colony collapses across the globe are threatening their vital work.

Bees are dying from a combination of pesticides, habitat destruction, drought, nutrition deficit, global warming and air pollution among other factors.

Greenpeace has reported: 'The bottom line is that we know humans are largely responsible for the two most prominent causes: Pesticides and habitat loss.'

This is important for a number of reasons, chief among them the amount of work bees put into our food production.

Vegetables, nuts and fruits are pollinated by bees. Of the top human food crops, a whopping 70 of 100 are pollinated by the creatures, which account for as much as 90 per cent of global nutrition.

Greenpeace has suggested the following solutions to the problem:

• The preservation of wild habitats in order to protect pollinator health
• The restoration of ecological agriculture
• The elimination of the world's most dangerous pesticides