How Fertilization and Pesticides Are Decimating Butterflies

Josef H. Reichholf, a German biologist, details in his latest book the consequences of the 80% decline in moth populations over the last 50 years.

 Josef H. Reichholf (Lower Bavaria, Germany, 76 years old) explains that he is barely aware of his earliest memories of butterflies; he used to see them fluttering around his garden. However, he has not forgotten the time when, as a small child, he caught one, taking great care not to damage it, so that he could observe it quietly: "It was so impressive that it has remained in my memory to this day. Over the years he began to study the number and abundance of these insects, especially the nocturnal ones, which account for 90% of all the butterflies that fly daily in Central Europe and whose number of species is 10 times greater than that of the diurnal ones, according to the biologist. "The importance of those that fly at night is much greater than those that fly during the day. They are food for others. They act as key elements in the ecosystem," he points out.

After more than two decades of research, this evolutionary biologist realized that the number of these insects is decreasing. The observations have continued over the years and he has just published in Spain his latest book, called La desaparición de las mariposas (Crítica), where he shows the results. In it he reflects the decrease of moths by more than 80% in the last 50 years in his study area: the periphery of a population of southeastern Bavaria. The causes are multiple, but the main ones are in the hands of humans with the extensive use of pesticides and fertilization, he says.

"Nocturnal butterflies act as key elements in the ecosystem."

Reichholf points out that, although it is widespread, countries such as Germany, the Netherlands and others in the north are much more affected by this decline in butterflies than those in the south. The most important causes of this phenomenon are related to cultivation. The problem with pesticides, he argues, is that they do not only act against pests, but also outside the fields, on the natural vegetation. As for fertilization, the scientist explains that very useful conditions have been created for a small number of plant species and that these are displacing the rest: "The vegetation is becoming very simple, composed of a few species that are highly tolerant to nitrogen and that outcompete the more sensitive plants. Therefore, the butterflies are going to lose their plants". He further specifies that close to the ground the vegetation creates "cooler and wetter conditions", but that these are "very different" where fertilization is at a higher level than normal. This is why even in non-poisoned areas, butterfly numbers are declining. Contrary to what most would think, cities with orchards and parks act as a "little refuge" for the smaller animals.

It is necessary to add conservation measures in non-agricultural areas, such as road verges, which especially affect the habitat of butterflies and, with these actions, even destroy them.
Global warming also has an important place in this issue. Whether it will have a positive or negative impact in the coming years depends on the location: "In the short term, global warming in the northern Alps will be better for butterflies and other insects, because most of the latter depend on warm temperatures. However, there are landscapes that are too large and are drying out and turning into deserts, and therefore the abundance of butterflies will decrease again," he concludes.

The consequences of reduced Lepidoptera populations are reflected in changes in other animals. Reichholf explains it through birds, whose species, in many cases, depend on certain "minimum quantities" of caterpillars and flying individuals such as day and night butterflies.

Government policies

The author, who has published a dozen books in his country, criticizes that "the German government's action is more or less close to nothing." "The best results have been obtained through the involvement of nature conservation corporations and ordinary people whose gardens are free of pesticides. Private commitment is more important than government actions for environmental protection." Another point of contention is the protection law for the preservation of butterflies because he feels that the current legislation does not work as it does not take into account the relevant issues. "It is a small part of the population that poisons and destroys nature," he accuses.

"Agriculture must become a symbiosis with the general population and not a parasite."

This problem also affects the European Union. Reichholf proposes a regulation that combines agricultural subsidies with effects that are based on nature and not only on productivity. "Currently, the interest of the majority of the European population in the amount of fertilizers and the amount of pesticide use for agricultural production is not considered. Agriculture must become a symbiosis with the general population and not a parasite," he says.