Researchers at the Krefeld Entomological Society in western Germany have calculated the mass of flying insects from dozens of nature reserves and their latest set of figures show a seasonal decline of 76 per cent across all seasons. There is also a worrying drop of 82 per cent in the summer – the high season for insects indicating that the highest losses occur when biomass is highest during a season.
What is causing the drop? Weather and climatic changes seemed to have little bearing on the figures. Land use change didn’t seem to fit the decline either. In fact, in the areas studied, forest have increased in size and number, while grassland and water bodies have stayed the same. Instead, the researchers hypothesise that larger-scale factors must be involved, such as pesticides and agricultural intensification.
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Given that 94 per cent of the land studies are surrounded by agricultural fields, it is plausible that these protected regions could actually start becoming ecological traps of deadly chemicals. Identifying the cause ‘is urgent’ stresses the Krefeld team. ‘The widespread insect biomass decline is alarming, even more so as traps were places in protected areas that are meant to preserve ecosystem functions and biodiversity.’
The results support similar declines seen in specific butterfly and wild bee populations and suggest that the ‘flying community as a whole has been decimated over the last few decades’.