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The abundance of flying insects has plunged by three-quarters over the past 25 years, according to a new study that has shocked scientists. The cause of the huge decline is as yet unclear, although the destruction of wild areas and widespread use of pesticides are the most likely factors and climate change may play a role. The scientists were able to rule out weather and changes to landscape in the reserves as causes, but data on pesticide levels has not been collected.
The research, published in the journal Plos One, is based on the work of dozens of amateur entomologists across Germany who began using strictly standardised ways of collecting insects in 1989. Special tents called malaise traps were used to capture more than 1,500 samples of all flying insects at 63 different nature reserves. When the total weight of the insects in each sample was measured a startling decline was revealed. The annual average fell by 76% over the 27 year period, but the fall was even higher – 82% – in summer, when insect numbers reach their peak.
The research, published in the journal Plos One, is based on the work of dozens of amateur entomologists across Germany who began using strictly standardised ways of collecting insects in 1989. Special tents called malaise traps were used to capture more than 1,500 samples of all flying insects at 63 different nature reserves. When the total weight of the insects in each sample was measured a startling decline was revealed. The annual average fell by 76% over the 27 year period, but the fall was even higher – 82% – in summer, when insect numbers reach their peak.