Wildlife Column with Prof Ian Rotherham
Across areas of heather moorland and heath, like the Peak District National Park, or up in the North Yorks Moors for example, instead of the usual glorious purple swathes of colour rioting across the landscape, there is a dull brown.
This is a heather-specific little herbivorous insect called the ‘heather beetle’ which can cause devastation to heathland. The heather beetle or Lochmaea suturalis is a leaf-beetle or Chrysomelid. The adult beetle spends winter amongst moss or litter in the undergrowth of heather plants. At this stage they are in a dormant ‘diapause’, and remain as such until warmer spring weather brings a rise in soil temperature. This warmth brings the adults out of dormancy and they emerge, feed, and reproduce. Able to fly up to several miles after spring emergence, they generally only do this after fire, when heather in the immediate area is of poor quality, or if the heather has been replaced by grassland. The beetle does have a degree of resilience to adverse conditions and can survive for some time in grassland such as wavy hair-grass.
So the big question is why is this year so bad and the beetle so devastating? Probably there is a big influence of hot weather and maybe climate change is having an impact. Heat and drought, and heather condition are important. It seems most likely that spring and summer conditions are the key and winter weather, such as cold, is less significant. Atmospheric pollution such as nitrogen fallout from things like car exhausts probably makes damage worse. On a particular site, the heather canopy structure has an impact too. Young heather shoots are the least affected. This means that seedlings and young re-growth are the least affected. The beetle needs about 50% heather cover too and so a greater mix of plant species and breaking up of heather age will help limit damage.
The beetle is behaving as a typical herbivore with the ability to breed fast and produce lots of offspring. Our glorious wide landscapes of massed heather are all it could ever desire!
Professor Ian D. Rotherham, of Sheffield Hallam University, researcher, writer and broadcaster on wildlife and environmental issues.