It is a tale of survival for plants and insects

Butterflies feeding on a buddleia bush

Buddleias have survived the impacts of intensive agriculture

9 October 2018 by Simon Williams

Insect pollinators that have survived the impacts of intensive agriculture may be more able to resist future environmental changes than previously thought.

Pollination by insects, particularly bees, is vital to food production and humans because it affects the yield or quality of 75% of globally important crop types. In recent years, however, there has been increasing concern about the long-term stability of this service due to widespread declines in some species.

Despite the negative impacts of agricultural intensification on plants and insect pollinators, researchers at the Centre for Ecology & Hydrology (CEH) and the University of Reading found that species that remain in parts of the UK with a higher proportion of farmed land are more likely to survive a variety of potential environmental changes. Because these intensively farmed landscapes have already lost their most vulnerable species, they retain the insect and planet species that are more able to take whatever is thrown at them.

The study drew on six million records from more than 30 years of citizen science data from thousands of volunteers who recorded sightings of different species and visits to plants by pollinators such as bees, hoverflies and butterflies. These records helped researchers to identify 16,000 unique interactions between plants and pollinators across Great Britain and, for the first time, how these 'ecological networks' vary across different types of landscapes.

John Redhead from CEH, who led the study, said:

We think that that the plants and pollinators that remain in these landscapes represent the toughest species that can handle the stresses of intensive agriculture - the vulnerable ones are already long gone.

This means that they're also able to cope with many future changes, so although we hear about reported declines in our wildlife, this may buy conservationists some time before we start to see the remaining plants and pollinators in agricultural areas really suffer.

The plants that have survived intensive agriculture include common weed species like brambles and thistles, which can cope with increased soil fertilisation and reduced water availability. Meanwhile, the insects that have fared better are 'generalist' pollinators that can feed on a wide variety of plant species, including crops and weeds, plus can cope with fewer and more scattered floral and nesting sites.

Professor Tom Oliver from the University of Reading, who co-authored the paper, which is published in the Ecology Letters journal, said:

It is good news that the catastrophic loss of all species is less likely, but we still need to work hard to restore biodiversity to give these ecosystems the best chance under growing threats of climate change and pollution.

Here are some examples of species who have either declined or survived under agricultural intensification:

Losers

  • shrill carder and brown banded carder bees
  • arable plant species such as corn marigold, corn buttercup and cornflower
  • traditional meadow species such as horseshoe vetch, common rockrose and harebell.

Winners

  • common bumblebees
  • classic weed species such as bramble, cow parsley, spear thistle
  • non-native species such as buddleia.

'Potential landscape-scale pollinator networks across Great Britain: structure, stability and influence of agricultural land cover' - John W Redhead, Ben A Woodcock, Michael JO Pocock, Richard F Pywell, Adam J Vanbergen, Tom H Oliver, 2018, Ecology Letters.