Gardeners are being encouraged to work with their neighbours to help support moths and hoverflies, after research revealed these insects to be particularly sensitive to urban environments.

Although bees tend to attract most of the attention when it comes to supporting pollinators in towns and cities, researchers have found that their less celebrated – though equally important – counterparts from other insect groups are even more severely affected by urbanisation.

A team of three researchers from the University of Sheffield’s School of Biosciences examined the impact of urban development on pollinators in the UK. They discovered that urban areas support 43% fewer pollinator species, with the steepest declines recorded closer to the city centre.

Emilie Ellis, the lead author of the study who carried out the work as part of her PhD, said: “The original focus was going to be on bees as they’re the most charismatic species.

“But then my interest in moths added this on to it, and then [co-author Stuart Campbell]’s interest in flies included hover flies. That’s the kind of cool novelty of this manuscript, that we included three different pollinating groups that are very diverse.”

The study, conducted during the summer of 2019, involved Ellis visiting allotments in Leeds, Leicester and Sheffield, covering areas with differing levels of urban density, to sample the range of pollinating insects from all three groups.

“We just collected insects every month for six months in eight sites in each city – so it was a lot of driving.”

The results were stark. For every 10% rise in hard, impermeable surfaces – such as roads and buildings – there was a reduction of up to 7.5% in the diversity of pollinating species. However, moths and hoverflies were far more heavily affected than bees.

Yet this very vulnerability may also point towards a solution. If gardeners and urban planners take account of the needs of a wider range of pollinators, there are relatively simple steps that can be taken to provide for them.

“We hypothesise that this could be due to the fact that they’ve got more complex life cycles because they need those different kind of resources other than flowers to become adults,” Ellis said. But that crucial vulnerability also contains a potential answer. If gardeners and urban planners bear in mind the needs of other pollinators, then there are straightforward ways to cater to them.

“We’re so good now planting flowers for pollinators like bees and that could be the reason why we’re not seeing them decline,” Ellis added. “It’s just a matter of taking these guys into account and maybe having some more shrubs or a pond or something like that to also benefit those insects.

“The diversity of habitat is the most important – so you need your flower patch, you need a tree, you need some shrubs, you need an untouched bit of grass – and kind of just keeping the patches that you have diverse and catering for all different types of insects and animals.

“A huge thing that’s important is collaborating and talking to your neighbours and families and friends and encouraging them to do it too. Because an individual allotment or flower garden is pretty small and almost useless, but when you create a whole network of people that are interested and engaged these small little patches can become these huge habitat networks in cities.”

The findings by Ellis and her colleagues have been published in the Royal Society’s biological research journal Proceedings B.

 

——————————————————————————

At Natural World Fund, we are passionate about restoring habitats in the UK to halt the decline in our wildlife.