Approximately half of all insects have been lost since 1970 due to the heavy use of pesticides, which could spell disaster for all life on Earth, a new report suggests.
The analysis, written by one of the UK’s leading ecologists, has a particular focus on the UK, whose insects are the most studied in the world. The use of pesticides, which has doubled over the last 25 years, has seen 23 species of bees and wasps go extinct.
Eighty-seven percent, almost all plants require animal pollination, most of it delivered by insects – meaning the global human population could not be fed without insect pollination.
“Information about insect populations in the tropics, where most insects live, is sparse. We can only guess what impacts deforestation of the Amazon, the Congo or South East Asian rainforests has had on insect life in those regions,” the report says.
UK butterflies that specialise in particular habitats have fallen 77% since the mid-1970s and generalists have declined 46%, the report said. There are also knock-on effects on other animals, such as the spotted flycatcher which only eats flying insects. Its populations have dropped by 93% since 1967.
Collapses in bug populations have been reported in Germany and in Puerto Rico. And a global scientific review published earlier this year estimated that, on average, the number of insects is declining by 2.5% each year, with more than 40% of insect species threatened with extinction.
But conservationists said that insect populations can be rescued, by introducing firm targets to cut pesticide use and making urban parks and gardens more wildlife friendly. Scientists said insects are essential for all ecosystems, as pollinators, food for other creatures, and recyclers of nutrients.
Virtually all farms could significantly cut their pesticide use while still producing as much food, according to a 2017 study. The research also showed that chemical treatments could be cut without affecting farm profits on three-quarters of farms.
“We can’t be sure, but in terms of numbers, we may have lost 50% or more of our insects since 1970 – it could be much more,” said Prof Dave Goulson, at the University of Sussex, UK, who wrote the report for the Wildlife Trusts. “We just don’t know, which is scary. If we don’t stop the decline of our insects there will be profound consequences for all life on earth [and] for human wellbeing.”