What's Happening To Our Butterflies And Bees?
Insectageddon! scream the headlines. Really? And why should this be? The more bizarre claims on social media I've seen recently range from Electro Motive Force to chemtrails (again - groan). What is actually happening to our butterflies and bees here in the UK?
Rather than just getting annoyed with people on Twitter, I thought it might be helpful to write a quick blog based on the most recent evidence update from the National Pollinator Strategy Plan.
This is a good thing. It's a 10 year plan to protect our pollinators. It includes a range of government, commercial, academic and non-government organisations. Recently a group of involved scientists specialising in bees and other pollinators published an evidence update for it. There are several findings here which might surprise you.
The Big Picture
To start with, what are the pollinators we're talking about? The main species are butterflies and bees, moths, hoverflies, and then there are others like wasps and beetles.
Very broadly speaking, most pollinators declined significantly from the 1950s - 1990. This is particularly true of less generalist species needing particular habitats and/or food. Take butterflies, for example; their numbers overall are down something like 40% from the mid seventies, but "habitat specialist" species are down by over 60%.
Since 1990 the trend has been down, but not so dramatically. In the short term a number of species actually seem to have stabilised. Phew!
This trend seems to be true of "wild" bees - that's to say, solitary bees (we have around 250 different types!) and bumblebees. Two of our 24 bumblebee species are on the verge of extinction here, for example, although some of the more common bumblebees are doing ok. Wild bees exhibit the same trend we're seeing in other invertebrates. The more common generalists are doing less badly than rarer specialist species.
Over the last decade the number of honeybees in the UK has gone UP - and by quite a lot, seemingly over 50% - as more people have taken up beekeeping and we've got better at disease control. This isn't quite the great news it sounds like, as wild bees do the bulk of our pollinating and we're only talking about one type of bee here.
Declines in nectar resources appear to have slowed since the 1970s and they actually increased from 1998 - 2007. They're still estimated to be below prewar levels, and the diversity of nectar-producing plants has continued to decline.
We are beginning to see some shortfalls in production (e.g. in apples) as a possible consequence of falling pollinator numbers.
Causes of Declines
Habitat loss and fragmentation and intensive land management have reduced food and nesting resources. Not only has this lead to declines in overall numbers, but it has disproportionately affected rarer, specialist species.
Chemicals to control pests and weeds, including neonicotinoids, have had a range of direct and indirect affects on pollinators. Urban insect pollinator communities are dominated by common, generalist species; we can see this pretty clearly for butterflies and bees.
Climate change will (continue to) have a number of impacts. Species range has and will change further, as will seasonal activity. The threat from invasive alien plants and predators will also increase.
The impact of the varroa mite on honeybee colonies appears to have been lessened by effective management techniques. We import bumblebees to pollinate crops like tomatoes, which can bring pests and disease.
Plant more flowers, and the right kind of flowers. This could include wildflower field margins and strips.
Protect and restore the flower rich semi-natural habitats we have - e.g. wildflower meadows, heathlands, broad leafed woodland.
Change the management of existing hedges, field margins, road verges, railway embankments, grassland, public green spaces, etc.. These are all potential sites for a wide range of wild pollinators.
Adopt more wildlife friendly land management practices, including organic farming and managing for ecosystem services. Hopefully we'll start to pay farmers to do this.
A phrase which recurs in the evidence summary is "established but incomplete". We spend so little on this kind of research it's not surprising. And it's complicated. We know a lot about honeybees, a reasonable amount about butterflies and moths, and less about bumblebees. Very little about other pollinators. The challenge is to have more "well established" facts. Let's leave absolutely no doubt that some of the things you read about butterflies and bees are fake news. We're working on it.
In the meantime, at the very least we can all plant or sow plants for pollinators - more of the right sort of flowers - and buy organic food as much as we can afford to. Plants are - as usual - the key.