Overige insecten

With summer gone at last after a blissful final fortnight of sunshine, I wish to advance a proposition with which many people may disagree: having fewer wasps around is not necessarily a good thing. In Britain, wasps are high on the list of nature’s unloved creatures. With their propensity to swarm around our picnics, seek out our sandwiches and then sting us painfully if we try to swat them away, the unpopularity of wasps is great and understandable. So if I say that the more common wasps are tumbling in numbers you may well give a hearty cheer. But I’m afraid I won’t join in, for this decline represents another facet of a very troubling phenomenon: the catastrophic crash of our insect populations over recent decades, almost certainly because of the amount of pesticides now used in farming.

Jede dritte untersuchte Art in Deutschland ist nach Angaben des Bundesamts für Naturschutz (BfN) gefährdet. Das geht aus dem ersten umfassenden Artenschutz-Report hervor. Laut Artenschutz-Report kommen in Deutschland insgesamt rund 72.000 Tier-, Pflanzen- und Pilzarten vor. In der Roten Liste wurden über 32.000 heimische Spezies auf ihre Gefährdung hin untersucht - mit einem nach BfN-Einschätzung ernüchternden Ergebnis: Rund 31 Prozent sind in ihrem Bestand gefährdet, vier Prozent bereits ausgestorben. Besonders dramatisch ist dem Bericht zufolge die Situation bei den wirbellosen Tieren, zu denen Insekten gehören: Knapp 46 Prozent der untersuchten Arten und Unterarten sind bedroht, extrem selten oder ausgestorben. Die Situation bei den Brutvögeln hat sich laut Bericht spürbar verschlechtert. Beim Kiebitz hat sich demnach der Bestand auf ein Drittel bis ein Viertel reduziert. Beim Rebhuhn gebe es sogar einen Rückgang von 90 Prozent. In Europa ist fast jede dritte Vogelart vom Aussterben bedroht oder steht auf der Warnliste, wie ein Bericht der EU-Kommission und der Europäischen Umweltagentur (EEA) zeigt. Hauptverursacher für den Rückgang vieler Arten sei die Landwirtschaft.

Industrial agriculture, with its heavy use of chemical pesticides, pollutes our water and soil and leads to loss of habitats and biodiversity, according to a Greenpeace report. With almost one in four (24.5%) vulnerable or endangered species in the EU being threatened by agricultural effluents, including the use of pesticides and fertilizers, species survival and crucial ecosystem services, like pollination, are at risk. Political and financial support is urgently needed to shift from chemical-intensive, damaging agricultural methods, to sustainable ecological farming practices. In Europe, a catastrophic decline of insects was signaled by the "IUCN Task Force on Systemic Pesticides" in 2015, after analyzing over 800 scientific reports. The impacts can be devastating, as 70 per cent of the 124 major commodity crops directly used for human consumption like apples and rapeseed are dependent on pollination for enhanced seed, fruit, or vegetable production. Dirk Zimmermann, Ecological Farming Campaigner at Greenpeace Germany said: "Europe's dependency on chemical pesticides is nothing short of an addiction. Crops are routinely doused with a variety of chemicals, usually applied multiple times to single crops throughout the whole growing season. Non-chemical alternatives to pest management are already available to farmers but need the necessary political and financial support to go mainstream."

Naturschützer warnen vor einem „neuartigen Insektensterben“. Forscher stellen im Verlauf der Jahre an manchen Standorten bis zu 80% Rückgang fest. Die Falle ist eine Art Luftreuse. Insektenkundler vom Entomologischen Verein Krefeld bauen sie auf, nach einiger Zeit schauen sie nach, was da so drin ist – Mücken, Schwebfliegen, Bienen, Käfer & Co. Seit vielen Jahren schon sind die Krefelder Fachleute mit der immer gleichen Fangmethode im Rheinland und anderswo unterwegs, teils an den gleichen Standorten. „Zugenommen hat die Menge der gefangenen Fluginsekten nirgendwo“, berichtet einer aus dem Verein. Im Gegenteil: Die Fachleute haben in den letzten 10 bis 15 Jahren mitunter dramatische Rückgänge festgestellt, an manchen Standorten wurden 70 - 80% weniger Insekten gefangen.

Farmland is home to hundreds of plant and thousands of animal species, many of which are highly dependent on each other forming a complex food web. This was first revealed by our early work on the grey partridge in Sussex. The population of grey partridge was partially dependent on the survival rate of the chicks, which in turn depended on them sourcing enough protein-rich insects. The insects that were most important to the chicks were largely weed-feeding species, and as a consequence, insect abundance was controlled by the management of the crop, but especially by the levels of herbicide inputs. Thus, herbicides were identified as causing an indirect effect on the number of insects within the crop, but also ultimately on the population of grey partridge. Herbicides also reduce the abundance of vegetation and weed seed that are important food sources for insects, birds and small mammals. The indirect effects of pesticides are now a recognised phenomena and along with direct effects are considered responsible for the decline of many other farmland birds because all of them, with the exception of pigeons and doves, feed their young insects during the first few weeks. Autoecological studies have helped to identify the causes behind the decline of some farmland bird species, such as those conducted on grey partridge, corn bunting and yellowhammer. These revealed a strong relationship between invertebrate food availability during breeding and breeding success and this was consequently linked to population change. The majority of other farmland birds also feed their chicks invertebrates because they provide the necessary protein for growth and the energy to resist chilling.

Von den über den Globus krabbelnden 12.000 Ameisenarten sind in Deutschland etwa 100 heimisch. Nach dem 1. Artenschutzreport des Bundesamtes für Naturschutz (BfN), der vor kurzem vorgestellt wurde, nimmt die Population der heimischen Ameisen aber ab. Eine Art gilt sogar schon als ausgestorben. 56 Arten sind bestandsgefährdet. Überall verschwinden die Ameisen. Im Wald etwa durch die Abholzung und sofortige Verwertung von Bäumen. Totholz, das Ameisen und anderen Insekten als Lebensraum dient, fehlt weitgehend. Für die Moor-Ameise gibt es immer weniger Lebensraum, die meisten Moore sind schon trocken gelegt. Einen besonders spürbaren Rückgang sehen die Forscher bei der Kerb-Ameise und der Großen Wiesenameise, die das offene Land besiedeln. Die Ameisenforscher fordern, dass 10 Prozent aller Waldflächen in Ruhe gelassen werden. Bei Renaturisierungsmaßnahmen sollten die Ameisenbestände eine Rolle spielen. Und generell gehe es um mehr Verständnis für die Ameisen und deren Lebensräume.

Neonicotinoids are a new group of insecticides, and little is known about their toxicity to nontarget freshwater organisms an potential effects on freshwater ecosystems. The aim of this study is to establish the acute toxicity and histopathological effects of thiamethoxam-based pesticide on the gill tissue of Gammarus kischineffensis. In this study G. kischineffensis samples were exposed to 2.5, 5, 7.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90 and 100 mg/l of commercial grade thiamethoxam for 96 h. The 24, 48, 72 and 96 h LC50 values were determined as 75.619, 23.505, 8.048 and 3.751 mg/l respectively. In histopathological study the individuals were exposed to 0.004, 0.04 and 0.4 mg/l thiamethoxam concentrations for 14 days. The results showed that the most common changes at all doses of thiamethoxam were vacuolization and hemostatic infiltration in the gill tissue of G. kischineffensis.

There is growing concern about increased population, regional, and global extinctions of species. A key question is whether extinction rates for one group of organisms are representative of other taxa. We present a comparison at the national scale of population and regional extinctions of birds, butterflies, and vascular plants from Britain in recent decades. Butterflies experienced the greatest net losses, disappearing on average from 13% of their previously occupied 10-kilometer squares. If insects elsewhere in the world are similarly sensitive, the known global extinction rates of vertebrate and plant species have an unrecorded parallel among the invertebrates, strengthening the hypothesis that the natural world is experiencing the sixth major extinction event in its history.