Alberton Record has investigated the rapid decline of insect species across Europe, a phenomenon that is often an indicator of a dire situation.
The biomass of flying insects captured in German nature preserves has decreased by a seasonal average of 76% between 1989 and 2016, according to a report published in the journal PLOS One.
Driving through the countryside in summer used to be synonymous with splattered insects on your windscreen. Not anymore.
Biologists call this the windshield phenomenon. They say it’s a symptom of vanishing populations of insects.
“The windscreen phenomenon is probably one of the best illustrative ways to realise we are dealing with a decline in flying insects,” said Caspar Hallmann, an ecologist at Radboud University in the Netherlands. Hallmann is part of the research team that studied insects collected in German nature preserves over a period of 27 years.
Insects were collected at 63 locations in Germany, including grasslands, swamps, sand dunes, wastelands, shrubland and along the margins of human settlement. All of the locations were protected areas.
“This decline happened in nature reserves, which are meant to preserve biodiversity and ecosystem functioning,” Hallmann said. “This is very alarming!”
Many of the insects that are decreasing in number are regarded as pests – bloodsuckers or crop-eaters – but many are essential to a healthy ecosystem. Mosquitoes, for instance, play a vital role as food sources for fish and other animals. Insects bury animal dung, prey on pests and pollinate plants.
German fieldwork researchers caught insects in what’s called a malaise trap.
Insects fly into the tented fabric, which funnels them into a collecting jar. The scientist gauged bug captures by mass. It’s an assessment of abundance, not diversity, a measure that scientists call biomass.
The most dramatic reduction over time in bug biomass appeared in summer months, when insects should be most active.
“Apparently, when insect densities are the highest, declines are most severe. Unfortunately, we do not know why,” Hallmann said.
Scott Black, executive director of the Portland, Oregon-based Xerces Society, a nonprofit environmental group that promotes insect conservation, said: “If you like to eat nutritious fruits and vegetables, you should thank an insect. If you like salmon, you can thank a tiny fly that the salmon eat when they’re young.
“The whole fabric of our planet is built on plants and insects and the relationship between the two.”
The authors of the new study attempted to find the reasons for the decline. Their investigations into climatic changes and other variables eliminated most of the “prime suspects,” Hallmann said. He said that the temperature increase observed over the study period should, in fact, have benefited flying insects.
Entomologists know that climate change and the overall degradation of global habitat are bad news for biodiversity in general, and that insects are dealing with the particular challenges posed by herbicides and pesticides, along with the effects of losing meadows, forests and even weedy patches to the relentless expansion of human spaces, The New York Times Magazine reported.
There are studies of other, better-understood species that suggest that the insects associated with them might be declining.
People who studied fish found that the fish had fewer mayflies to eat. Ornithologists kept finding that birds that rely on insects for food were in trouble: eight in 10 partridges are gone from French farmlands; there are between 50% and 80% drops, respectively, for nightingales and turtledoves. Half of all farmland birds in Europe disappeared in just three decades.
At first, many scientists assumed the familiar culprit of habitat destruction was at work, but then they began to wonder if the birds might simply be starving.
The current worldwide loss of biodiversity is popularly known as the sixth extinction: the sixth time in world history that a large number of species have disappeared in unusually rapid succession, caused this time not by asteroids or ice ages but by humans.
But all is not doom and gloom, Black said.
“Although I get depressed every time a study like this comes out, I see tens of thousands of everyday people engaged in managing their own little piece of earth in a better way. Helping these tiny helpers can take only a small effort.
“Habitat restoration can be as simple as a garden with plants that flower throughout the year. Unlike mammals, insects don’t require vast tracts of land to be satisfied – a back yard blooming with native flowers will do.”
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