A survey finds that between 2004 and 2021 there has been a huge decline in the number of “insect splashes per mile” on cars in the UK, with a particularly severe drop in England.
May 5, 2022
The new evidence suggests there is some truth to anecdotes about today’s car windshields being covered with fewer dead bugs than in the past.
A UK citizen science survey found that the number of flying insects splashed on cars dropped by 58.5 per cent between 2004 and 2021, after drivers counted how many were squashed onto their number plates. “It’s dramatic and alarming,” says Matt Shardlow of Buglife, the charity that led the work.
Fears have grown in recent years that due to the loss of pollinators, some food crops could be undermined by a global decline in insects, and a recent study found that climate change and agriculture have nearly halved the number of insects in the most affected regions. But most of the monitoring of flying insects is based on their distribution, rather than their abundance.
To get a better idea of how flying insect populations are changing, Buglife recruited drivers to clean their license plate before a trip and then use a sampling grid (a “platometer”) to count the number of insects dead when they reached their destination and upload the results to an app. By dividing the number of insects by the distance traveled, the researchers arrived at a unit of “splashes per mile.”
This measure fell from 0.238 per mile on average in 2004 to 0.104 per mile in 2021, or a drop of 58.5 per cent across the UK. “This confirms what we already knew: that insect populations are in free fall. There doesn’t seem to be a credible explanation for these findings other than a massive decline in insect abundance,” says Dave Goulson of the University of Sussex, UK, who was not involved in the research.
The rate of decline is similar to that reported by a 2017 study, which found a 76 percent drop in biomass of flying insects in Germany over 27 years.
The drop found by the Buglife survey was greatest in England at 65 per cent, reached 55 per cent in Wales and was least in Scotland at 27.9 per cent. Shardlow says that possible explanations for the regional differences are less light pollution, less insecticide use due to less arable agriculture, and less impact of climate change further north.
A paper published last month found that moth numbers in the UK more than halved between 1968 and 2016 in one of its key habitats, broadleaf woodland, even as woodland area expanded. during the period. The authors said climate change could be partly to blame.
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