WASHINGTON (Reuters) – Ants, bees, butterflies, grasshoppers, fireflies and other insects that live in the world suffer population drops of around 9% per decade, but freshwater insects such as dragonflies and mosquitoes are recovering, researchers said on Thursday.
ARCHIVE PHOTO: A bee lands on a bell in a garden in West London, England, April 23, 2020. REUTERS / Toby Melville / File Photo
The findings, based on 166 data sets, covering 1,676 locations in 41 countries, dating from 1925, provided a differentiated assessment of insects, the most ubiquitous and diverse animals on the planet, with the strongest declines documented in the Midwest United States and In Germany.
Insects such as mosquitoes – which live in the water like larvae – as well as mosquitoes, mayflies, water beetles and caddisflies that spend at least part of their lives in fresh water – have been found to experience a population increase of around 11% per decade.
Fresh water covers only about 2.5% of the Earth's surface; therefore, the vast majority of insects live on land.
The number of insects on average decreased in the air, on the grass and on the surface of the soil, but not on the trees or underground, the researchers found.
Projecting trends into the future shows that insects living on land would sustain a population drop of 24% in 30 years, while freshwater insects would suffer a 38% increase in the same period.
"Insects are a central part of almost all ecosystems, because they are in the middle between the plants they eat and the animals that eat insects, such as birds, bats and lizards," said entomologist Roel van Klink, from the German Center for Integrated Research in Biodiversity, main author of the research published in the journal Science.
"They also affect our own lives, usually in ways we don't think about. Insects pollinate many of our crops, and without them we would have no fruit or flowers. But at the same time, insects transmit terrible diseases like malaria, zika and viruses. West Nile, eat our crops and damage tree plantations, ”added van Klink.
The study did not detail the results by species. There was little data from South Asia and the Middle East and limited data from Africa.
The researchers credited the clean water policies instituted in recent decades by the increase in freshwater insects.
They attributed the decline in insects that inhabit the land to human activities, such as habitat destruction and fragmentation, urbanization, light pollution and chemical pollution, while increasing insecticides and droughts due to climate change may also have played a role.
Reporting by Will Dunham; Editing by Sandra Maler
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