Ecology: Insect numbers down 25% globally since 1990

The Guardian said:

The biggest assessment of global insect abundances to date shows a worrying drop of almost 25% in the last 30 years, with accelerating declines in Europe that shocked scientists.

The analysis combined 166 long-term surveys from almost 1,700 sites and found that some species were bucking the overall downward trend. In particular, freshwater insects have been increasing by 11% each decade following action to clean up polluted rivers and lakes. However, this group represent only about 10% of insect species and do not pollinate crops.

Researchers said insects remained critically understudied in many regions, with little or no data from South America, south Asia and Africa. Rapid destruction of wild habitats in these places for farming and urbanisation is likely to be significantly reducing insect populations, they said.

Insects are by far the most varied and abundant animals, outweighing humanity by 17 times, and are essential to the ecosystems humanity depends upon. They pollinate plants, are food for other creatures and recycle nature’s waste.

The previous largest assessment, based on 73 studies, led scientists to warn of “catastrophic consequences for the survival of mankind” if insect losses were not halted. Its estimated rate of decline was more than double that in the new study. Other experts estimate 50% of insects have been lost in the last 50 years.

Recent analyses from some locations have found collapses in insect abundance, such as 75% in Germany and 98% in Puerto Rico. The new, much broader study found a lower rate of losses. However, Roel van Klink, of the German Centre for Integrative Biodiversity Research in Leipzig, who led the research, said: “This 24% is definitely something to be concerned about. It’s a quarter less than when I was a kid. One thing people should always remember is that we really depend on insects for our food.”

...

Click to expand...