Check out the first installment of this post, Insect Profile: The Apollo.
“An interview with Andreas Segerer”
We are standing in a hallway across from a hidden treasure: the world’s largest collection of butterflies and moths, holding about 13 million specimens. Some parts of the collection date back to the 1760s; some historic sections have been carefully gathered and annotated by the likes of explorer and zoologist Princess Therese of Bavaria (1850–1925). The collection at the Zoologische Staatssammlung München is a testament to the world’s astounding diversity of butterflies and moths—and of the passion, patience, and curiosity of those who have collected and mounted them. At the office, we meet—in his own words—one of the last kindred spirits of moths and butterflies. Andreas Segerer, one of just a handful of lepidopterists in Germany, speaks to us about his personal and scientific experiences of insect loss, which are deeply entwined. He is the chief moth expert at the Bavarian State Collection of Zoology.
When I was young, at the tender age of five, I collected my first butterflies behind the house. Nobody else in my family has ever collected them, except for an uncle. The urge to hunt, gather, and explore has been a common theme throughout my life.
As a researcher, I became interested in insect extinction through the DNA barcoding project, which aims to identify all Bavarian animal species genetically. We obtain their genetic fingerprint, so to speak. That meant spending a lot of time in the field. Bavaria covers a fifth of Germany’s surface area and Lepidoptera are the fourth largest animal kingdom. Besides the Krefeld study, the database of our recent catalog of the Lepidoptera of Bavaria is the largest of its kind in Germany. We have about 35,000 animal species in Bavaria and more than 3,000 Lepidoptera—so, 10 percent of all animals living in Bavaria are actually butterflies and moths. They are indicator species that teach us about how healthy an ecosystem is.
Because so many amateurs collect them for their beauty, we have a very good idea of how Lepidoptera numbers have changed—even from before the Industrial Revolution. Our huge historical collection at the State Collection of Zoology gives us a good impression of the dramatic loss of species and populations. For scientists, insect extinction is not much of a surprise. We have been aware of it for decades.
When I grew up in Regensburg, I was in touch with the local collectors. They were mostly elderly gentlemen. There must be something in the air in Regensburg. Lepidopterists have always been around there. I am the last one. In the 1970s, the collectors told me: “There is nothing left.” Looking back today, the 1970s were like a paradise. From today’s perspective, we were surrounded by abundance. From the collectors’ prewar perspective, it was rather unimpressive. Regensburg is very well researched both by professional and amateur scientists. As early as 1854, those researchers stated that there was a decline in butterflies and moths. We have written sources from that time which stress that it was not collectors, but the shift in land use, the intensification of agriculture, and the disappearance of hedges that have caused the decline. This is very timely—it could have been written today.
I will give you an example from my childhood in Regensburg.
During the first three weeks of August, during summer break, I always counted the butterflies—the European peacocks (Inachis io) and small tortoiseshells (Aglais urticae)— that fed on the buddleja (commonly called “butterfly bush”) in our garden. As a teenager, I did not establish a scientific protocol, of course, but even by the most conservative estimation, I found 500 butterflies, maybe 1,000, during the summer break. In the same garden in 2016, I saw only four butterflies during the whole year. It was the same garden—not the same shrub though, but still a buddleja.
We know of 3277 Lepidoptera species in Bavaria. By now, most of their populations have declined by 90 percent. Many are even extinct. And some have slipped below the identification threshold. To date, we have lost 388, or twelve percent, of species.
In the 1960s and ’70s, the area where I grew up was a development area. It had poor soil, and stinging nettle grew there. That was where I collected the grubs. The ground has since been sealed. Today, if there still are stinging nettles at all, they are overfertilized. There are no development areas anymore. The growth of cities is the second biggest reason for insect extinction after the intensification of agriculture.
The use of fertilizer has grown and those specialized species that have adapted to meager conditions have disappeared. But why does this happen in the nature reserve of the Keilberg near Regensburg, where we do our research? The answer: chemical substances have far-reaching effects. Nitrogen in the forms of ammonia, and nitrous gases rise up from liquid manure and mineral fertilizer. They travel through the air and produce a fallout. This is called “aerial fertilization” and it explains the “miracle” of fertilization in conservation areas that previously had nutrient-poor soils (and flora adapted to those particular surroundings), and which were highly important for insect diversity. When land is fertilized with synthetic nitrogen the proportion of generalist species (those able to thrive on a varied diet and under a range of environmental conditions) increases; but overall, there is a strong general decline of species diversity. Specialized species that feed only on particular plants that grow in meager soils disappear because excess nitrogen leaches into the soil and changes the flora. There is also no evidence that new specialist species are profiting from climate change. Grass may be growing quicker now, but many specialists have given up because plant diversity has decreased.
The decline in biodiversity we see today, however, is itself an effect of human activity. There used to be forests around and nomadic shepherds, and certain forms of low-intensity farming mellowed the landscape and turned it into grasslands. Insect species from the Mediterranean migrated to Bavaria. The nineteenth century saw the greatest biodiversity around here.
Insect extinction is not simply a German or European phenomenon. The extinction rate of species is so great that we now talk of the sixth mass extinction in the Anthropocene. Nobody knows the tipping point. Politics has been unable to balance economic and ecological demands. If ecosystems collapse worldwide, there is nowhere else to go.
Insect extinction would be a disaster. Think of a tin can pyramid at the supermarket. If you take the bottom can out, everything collapses. Insects and their eggs are a food source for other organisms like parasitic wasps, birds, spiders, bats, and bacteria. The garden tiger moth (Arctia caja), for example, is a night moth that feeds on dandelions and lays up to 800 eggs. 798 of those eggs get eaten by other animals, parasites, or bacteria. If garden tiger moth populations collapse, this important food source disappears. In heavily fertilized areas, the number of birds decreases because they depend on insects. Some birds that usually eat insects have even begun to turn to eating seeds. Importantly, insects are the primary decomposers. If, for example, a wild boar dies in the forest, insects eat its body. Finally, the majority of plants depend on pollination. In China, humans have started to pollinate by hand. Compensating for insect pollination that way is impossible though. Besides, who would pollinate wild flowers, for instance?
We need to reduce our use of pesticides and fertilizer. Both produce a fallout that travels through the air and/or water. Honey samples from all over the world are laden with neonicotinoids. They may be polluted below the threshold that is dangerous to human health, but these levels are certainly affecting and even killing insects. All in all, a paradigm change in agriculture and urbanization is of primary importance.