Overige insecten

Der Deutsche Berufs- und Erwerbsimkerbund (DBIB) und der Bund für Umwelt und Naturschutz Deutschland (BUND) appellieren an die deutschen Landwirte, bei der anstehenden Raps-Aussaat freiwillig auf Pestizide zu verzichten, die zur Gruppe der Neonikotinoide gehören. Diese vor allem für Bienen gefährlichen Nervengifte werden zum Beizen des Saatgutes eingesetzt und sind nach Erkenntnissen von Toxikologen 6000 bis 7000mal giftiger als DDT. Untersuchungen ergaben, dass Neonikotinoide bei Bienen und Vögeln zu Einschränkungen der Orientierungsfähigkeit und zu Störungen des Immunsystems führen können. Außerdem töten diese Pestizide viele Insektenarten, die Vögeln als Nahrung dienten. Die EU-Mitgliedsstaaten hatten im April dieses Jahres beschlossen, ab 1. Dezember die drei gefährlichsten Neonikotinoide zunächst für zwei Jahre vom Markt zu verbannen. Betroffen von diesem Teilverbot sind die Wirkstoffe Clothianidin, Imidacloprid sowie Thiamethoxam. „Neonikotinoide sind für das Bienensterben und das Verschwinden von Vögeln in landwirtschaftlich geprägten Regionen mit verantwortlich. Wenn bei der Raps-Aussaat jetzt auf diese Agrargifte verzichtet wird, dann könnten sich Bienen- und Vögelpopulationen langsam wieder erholen“, sagte der BUND-Vorsitzende Hubert Weiger.

Lift a rock or log anywhere in the country and chances are you'll see beetles from many species scurrying beneath it. These unassuming creatures are often overlooked as more glamorous insects hog the spotlight. But a recent study shows that the populations of an important group of beetles are dwindling, and this could end up being just as problematic as the better-publicised problems of bees and butterflies. The research, published in the Journal of Applied Ecology, found that three quarters of the beetle species examined had declined in number over the last 15 years. The abundance of half of these species had fallen at a rate equivalent to 30 per cent per decade. Scientists warn that these declines, comparable to those seen in butterflies and moths over the same period, are of serious conservation concern. The study focused on ground beetles or 'carabids', the surface-dwelling group that most people will picture if asked to imagine a beetle. Many of these species perform valuable tasks in their ecosystems that we'd miss if they disappeared.

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Normalerweise sind die schwarz-gelben Insekten längst unterwegs, umschwirren jede Garten-Party und auch Papierkörbe auf der Suche nach zuckerhaltiger Nahrung. Und selbstverständlich gehören die Bäckereien mit ihren süßen Verlockungen zu ihren Zielen. Doch selbst dort sind die Wespen in diesem Jahr noch nicht aufgetaucht, wie Katja Koch von der Bäckerfiliale am Auerbacher Neumarkt bestätigt: "Ich habe noch keine einzige gesichtet, das ist schon ungewöhnlich. Aber böse bin ich nicht drüber."Dabei wartet diesmal im Laden eine elektrische Falle auf die Lästlinge, die sich sonst gern auf dem Kuchen tummeln - doch bislang hat die Technik kein Opfer gefordert. Auch in Obstläden oder beim Eisverkauf sind Wespen bislang Fehlanzeige - wobei sie eigentlich niemandem fehlen. Gerade für Allergiker sind ihre Stiche der blanke Horror, und auch sonst haben die manchmal aggressiven Insekten mit der spezifischen Taille wenig Freunde. Auch Imker Peter Tröger aus Rodewisch steht nicht auf Wespenstiche: "Die schmerzen drei Tage lang, bei Bienen ist es dagegen schnell vorüber." Doch auch die Wespen hätten eine wichtige Funktion im Kreislauf der Natur: "Sie sind die Reinigungspolizei, schaffen Unrat wie Speisereste oder Kadaver schnell weg." Probleme mit Menschen gebe es vor allem dort, wo Nahrung nicht richtig gesichert oder achtlos weggeworfen werde. Sonst sind Wespen um diese Zeit auch an seinen Bienenstöcke zu Gast und naschen vom Honig, in diesem Jahr hat er sie noch nicht gesichtet. Das könne sich jedoch noch ändern, meint der Insekten-Experte: "Es ist ja alles ein paar Wochen später in diesem Jahr."

But in recent years more and more drivers seem to be finding their windscreens clear. Is it just a vague perception? Or might it correspond to something real and serious, the widespread disappearance of insects in general? Conservationists are starting to think the latter proposition is true. "Anecdotal evidence pointing to the decline of British insects abounds," said Dr George McGavin, acting curator of entomology at the Oxford University Museum of Natural History. "Most people over the age of 50 talk of seeing many more species of moths, butterflies and other insects when they were children." With a colleague, Dr McGavin in 2000 examined insect records in Warwickshire from 100 years ago and the present day, and found that about 20 per cent of the species surveyed (including beetles, bees, dragonflies and butterflies) had disappeared or were in marked decline. A closer examination showed that 394 beetle species alone had been lost, a decline of 24 per cent.

There is now compelling evidence of a reduction of pollinator richness and density at a global scale. In this opinion article, we argue that such pollinator decline intensifies pollen limitation and reduces plant reproductive success, threatening natural populations of extinction. We use genetic architecture and selection experiments on floral traits and evaluate the potential for plant reproductive strategies to adapt rapidly to new pollination environments. We propose that plant reproductive strategies could adapt to the current pollinator decline by decreasing or increasing their reliance to pollinators, for example, increasing autonomous selfing or reinforcing interactions with pollinators. We further discuss if and how adaptation of plant reproductive strategies can buffer the demographic consequences of pollinator decline, and possibly rescue plant populations from extinction.

There is mounting evidence of pollinator decline all over the world and consequences in many agricultural areas could be significant. We assessed these consequences by measuring 1) the contribution of insect pollination to the world agricultural output economic value, and 2) the vulnerability of world agriculture in the face of pollinator decline. We used a bioeconomic approach, which integrated the production dependence ratio on pollinators, for the 100 crops used directly for human food worldwide as listed by FAO. The total economic value of pollination worldwide amounted to €153 billion, which represented 9.5% of the value of the world agricultural production used for human food in 2005. In terms of welfare, the consumer surplus loss was estimated between €190 and €310 billion based upon average price elasticities of − 1.5 to − 0.8, respectively. Vegetables and fruits were the leading crop categories in value of insect pollination with about €50 billion each, followed by edible oil crops, stimulants, nuts and spices.

Population declines among insects are inadequately quantified, yet of vital importance to national and global biodiversity assessments and have significant implications for ecosystem services. Substantial declines in abundance and distribution have been reported recently within a species-rich insect taxon, macro-moths, in Great Britain and other European countries. These declines are of concern because moths are important primary consumers and prey items for a wide range of other taxa, as well as contributing to ecosystem services such as pollination. I summarise these declines and review potential drivers of change. Direct evidence for causes of moth declines is extremely limited, but correlative studies and extrapolation from closely related taxa suggest that habitat degradation (particularly because of agricultural intensification and changing silviculture) and climate change are likely to be major drivers.

A new review of insect pollinators of crops and wild plants has concluded they are under threat globally from a cocktail of multiple pressures, and their decline or loss could have profound environmental, human health and economic consequences. Globally, insects provide pollination services to about 75% of crop species and enable reproduction in up to 94% of wild flowering plants. Pollination services provided by insects each year worldwide are valued at over US$200 billion. The review, published on 22nd April 2013 in the scientific journal Frontiers in Ecology and the Environment, was carried out by an international team of 40 scientists from 27 institutions involved in the UK's Insect Pollinators Initiative (IPI), a £10m research programme investigating the causes and consequences of pollinator decline. Dr Adam Vanbergen, from the UK's Centre for Ecology & Hydrology (CEH) and science coordinator of the IPI, led the review. He said, "There is no single smoking gun behind pollinator declines; instead there is a cocktail of multiple pressures that can combine to threaten these insects. For example, the loss of food resources in intensively farmed landscapes, pesticides and diseases are individually important threats, but are also likely to combine and exacerbate the negative impacts on pollinators."

The legislation suspends certain uses of neonicotinoids, a particular type of pesticide that is suspected to play a role in the bee die-offs happening in Oregon and in bee declines around the world, until the Environmental Protection Agency reviews these chemicals and makes a new determination about their proper application and safe use. Dinotefuran, the neonicotinoid ingredient in Safari insecticide, is blamed for last month’s mass die-off in Wilsonville, OR of an estimated 50,000 bumble bees – the largest such die-off ever recorded. The Oregon Department of Agriculture is investigating the die-off and is temporarily restricting the use of 18 pesticide products containing dinotefuran.