Flying insects represent a massive portion of the food web, and significant losses spell ecological disaster. Photo by Getty Images/Mariusz Brainard.
Flying insect mass in Germany fell by 76 percent in less than three decades, according to entomologists who, in 2016, concluded a 27-year-long study on insect biomass. Midsummer losses were even more significant, at 82 percent. The researchers’ results were culled from samples pulled from 63 nature-protection areas across the country, and were published in PLOS ONE in October 2017, after which headlines titled the decline “Insect Armageddon,” and scientists warned of global implications. Many insects undertake tasks that are crucial to the health of their ecosystems, such as decomposition and pollination, and fewer insects means less food for every link in the food chain that follows.
The researchers discovered that their results were consistent across habitats, regardless of weather, land use, and habitat characteristics. Agricultural intensification, including the use of pesticides, could contribute to the issue, but the researchers weren’t able to incorporate that data into their analyses. They say they were especially alarmed by the unexplained decline because their samples were taken from areas that were meant to preserve diversity. The loss of diversity indicated by this study will have a cascading negative impact on food webs and ecosystems, the researchers report, and they urge further study of the causes, extent, and ramifications of this decline.
Since the publication of the PLOS ONE study, which you can find by searching for “flying insect biomass” on www.PLOS.org, other studies have confirmed dramatic drops in various insect populations. A report in the October 2018 issue of Proceedings of the National Academy of Sciences describes considerable climate-driven insect declines in Puerto Rico’s El Yunque National Forest, leading to subsequent declines in lizards, frogs, and birds.
In the face of limited long-term data, these studies add weight to anecdotal evidence about vanishing insects, but more research is needed to track and understand the significance of global insect declines.