Insect declines - then flowers and birds

Insects pollinate about 80 % of flowers and are the major food of approximately 40 % of birds. Recent news have shown unexplained deaths in bee colonies, and the possible effects of neonicotinoid-treated seeds on pollinating insects discussed. However, in all earlier cases intensive agriculture has been discussed as making a contribution to the insect problems.

In view of this the recent report by Hallmann et al (PLoS ONE 12, e0185809) is worrisome. The scientists have determined flying insect biomass in German nature protection areas for about 30 years. During that time the biomass has decreased more than 3/4. Further, no reasons which could explain the decrease have been found. The decrease has occurred similarly in insect-rich and insect-poor habitats, so it is a general phenomenon and not associated with the change in habitats.

Let's hope that we find the reasons and can stop the decline before flowers and birds start disappearing, although already decreases in many bird populations have occurred. As yet, it is not known if these declines can be associated with the disappearance of insects, but the possibility exists.