… the little things that run the world …
The title is lifted from a recent articale on the findings of a long-term entomology research group in Krefeld, Germany. [ Gretchen Vogel, Science, May 10 2017 ]
The group have been methodically trapping and recording insects in a number of nature reserves across the Krefeld region since early in the twentieth century, and in the last few years have become aware of huge differences between their 1980s trawls and current volumes. Hoverflies showed a particularly steep decline.
They make the point that the focus of public concern on loss of species (and Red List data) obscures issues of loss in common species.
the real problem…. is a loss not of biodiversity but a loss of bioabundance
Few species are listed as extinct because they are still found in one or two sites. But that obscures the fact that many have disappeared from large areas where they were once common. Across Germany, only three bumble bee species have vanished, but the Krefeld region has lost more than half the two dozen bumble bee species that society members documented early in the 20th century.
As one Canadian ecologist puts it:
We have a pretty good track record of ignoring most noncharismatic species, which most insects are…
Joe Nocera, University of New Brunswick in Canada.
Land use changes may be the main driver, but the period of decline also coincides with the rise of modern systemic insecticides. Professor Dave Goulson who has recently been studying cocktail effects of multiple pesticides, is now helping the German group to analyse their data.
Neonicotinoid pesticides, already implicated in the widespread crash of bee populations, are another prime suspect. Introduced in the 1980s, they are now the world’s most popular insecticides, initially viewed as relatively benign because they are often applied directly to seeds rather than sprayed. But because they are water soluble, they don’t stay put in the fields where they are used. Goulson and his colleagues reported in 2015 that nectar and pollen from wildflowers next to treated fields can have higher concentrations of neonicotinoids than the crop plants. Although initial safety studies showed that allowable levels of the compounds didn’t kill honey bees directly, they do affect the insects’ abilities to navigate and communicate, according to later research. Researchers found similar effects in wild solitary bees and bumble bees.