German nature preserves have lost 75 percent of their flying insects

"As entire ecosystems are dependent on insects for food and as pollinators, it places the decline of insect eating birds and mammals in a new context," said researcher Hans de Kroon.
By Brooks Hays  |  Oct. 18, 2017 at 4:12 PM
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Oct. 18 (UPI) -- Germany's insect population has declined precipitously inside protected preserves over the last three decades, new research shows.

Between 1989 and 2016, the biomass of flying insects declined by 75 percent across 63 nature reserves, according to a new study published in the journal PLOS ONE.

Although much attention has been paid to the decline of bees and butterflies, the latest findings suggest a problem with a much wider scope.

"The fact that flying insects are decreasing at such a high rate in such a large area is an even more alarming discovery," Hans de Kroon, researcher at Radboud University in the Netherlands, said in a news release.

Since 1989, scientists have been trapping insects in large tents, called malaise traps, and measuring the total biomass. Over the years, scientists have captured fewer and fewer insects.

At 82 percent, the decline of insects biomass during midsummer, when insects populations tend to peak, proved more severe than the annual average decline.

Researchers say weather variability can explain some swings in the numbers of insects, but changes in vegetation and climate alone can't explain the severity of the broad decline.

Most of the 63 nature preserves in the study are surrounded by agricultural lands.

"These surrounding areas inflict flying insects and they cannot survive there," said Caspar Hallmann, researcher at Radboud. "It is possible that these areas act as an 'ecological trap' and jeopardize the populations in the nature reserves."

Scientists suggest their findings are likely indicative of continental, or even global, trends. Insects in preserves around the world likely face a similarly precarious fate.

The researchers recommend policy makers and conservationists proceed with extreme caution and dramatically curb activities proven to be harmful to insects. They also recommend the creation of preserves that don't border agricultural land.

"As entire ecosystems are dependent on insects for food and as pollinators, it places the decline of insect eating birds and mammals in a new context," said researcher Hans de Kroon. "We can barely imagine what would happen if this downward trend continues unabated."

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