Overige insecten

Wenig hoffnungsvoll klangen die Prognosen der Jagdpächter über den Wildbesatz in den einzelnen Revieren des Hegerings Altenoythe im Hinblick auf die anstehende Jagdsaison. Sie hatten sich jetzt zur Herbstversammlung in der Gaststätte Dumstorff getroffen. Bei den Fasanen lautete die Einschätzung: „wenig bis nichts“. Die Hasenstärke wurde von „wissen wir nicht“ über „vielleicht“ bis „geht und gut“ beschrieben. Bei den Kaninchen lautete der Tenor: „Sie sind wieder krank“. Aus allen Revieren hieß es, dass der Fuchsbestand stark rückläufig sei, da das Tier an Staupe erkrankt sei. Die Aufmerksamkeit der Altenoyther Jäger sicherte sich der Vizepräsident der Landesjägerschaft Niedersachsen, Josef Schröer, bei seinem mit großer Leidenschaft vorgetragenem Referat zum Thema „Artenvielfalt im Wandel der Landwirtschaft – Bleiben Hase, Fasan und Rebhuhn auf der Strecke?“. Schröer kritisierte die ohne Augenmaß auf Flora und Fauna vorangetriebene Entwicklung der Landwirtschaft, die von der Flurbereinigung über den Einsatz von Pestiziden und Insektiziden bis hin zu Biogasanlagen und den damit verbunden Monokulturen und deren Erntemethoden reichten. Neben den genannten Niederwildtierarten seien auch viele andere Tierarten fast aus der Natur verschwunden. Die Liste reiche vom Birkhuhn über Schnepfen, Kiebitz und Sperling bis zu den Insekten, und auch beim Niederwild sei „das Ende der Fahnenstange“ noch nicht erreicht. Er forderte mehr Biotope, Wallhecken, Blühstreifen und „Lerchenfenster“.

In a new study on ecosystems in the Midwest, scientists suggest that once-fertile landscapes dominated by tall grass prairies and supported by microbial biodiversity have been destroyed due to decades of agricultural production. The study, Reconstructing the Microbial Diversity and Function of Pre-Agricultural Tall Grass Prairie Soils in the United States, published in the journal Science, demonstrates the crucial role soil microbial diversity plays in ecosystem stability and health. Although soil microbes are inherently important for the breakdown of organic matter, the cycling of nutrients, as well as plant productivity, previous research has narrowly focused on the role of nitrogen fixing root fungi, rather than broader aspects of soil microbial diversity. Thus, this new study represents one of the first to delve into the importance of soil microorganisms in ecosystem restoration projects.

New Zealand is facing an invasion of Argentine ants (Linepithema humile), which compete with native southern ants (Monomorium antarcticum). The insects often meet in urban or agricultural areas, where neonicotinoids are in use. So ecologist Rafael Barbieri, a graduate student in the lab of Philip Lester at Victoria University of Wellington, wondered whether the behavioural changes that have been associated with sublethal neonicotinoid exposure in other insects affect how the two species interact. “Any changes in behaviour could potentially affect the structure of the entire community,” he says. As the team describes in Proceedings of the Royal Society B1, Barbieri exposed the ants to extremely low doses of a common neonicotinoid and examined how the insecticide affected each species’ behaviour. He did not observe an effect on the foraging behaviour or survivability of either species in isolation, although they did cut the brood size of the invasive Argentine ant in half. But it was when the two species met that the real effects were seen. When the southern ant was exposed to the potent neurotoxins, it became much less aggressive towards the invader. This increased the survival odds of the Argentine ant, and could help it to spread. However, when invasive ants were exposed to the insecticides, they became much more aggressive towards unexposed Southern ants — so aggressive, in fact, that they risked their own lives to attack. As a result, unexposed natives were able to completely eradicate their exposed rivals.

An increasing body of scientific evidence indicates that many chemicals have biological effects at doses previously considered negligible. It is increasingly evident that more subtle deleterious effects can occur due to longer-term exposure to relatively low doses of chemicals, individually or in mixtures. New concerns have recently been raised about the impact of pesticides on non-target organisms including insects, especially bees, and amphibians. Studies suggest that low doses of neonicotinoids, a group of neurotoxic chemicals widely used in many countries as insecticides, could have sublethal effects on honey bees and bumble bees with serious consequences for wild populations of these crucially important pollinators and therefore for agriculture and the environment. It has also been suggested that detailed investigation of the effect of neonicotinoids on mammalian brain function, especially brain development, is needed to protect human health, especially that of children.

A FLY which has apparently never ventured beyond a tiny strip of an east Highland beach could be facing extinction, scientists warn. Fonseca's seed fly is on the nation's Biodiversity Action Plan but a paper by Scottish Natural Heritage (SNH) highlights just how limited the insect's world is thought to be. Experts believe the fly, Botanophila fonsecai, is restricted to a 328-feet long strip of land on the north shore of the Dornoch Firth. The population is small and is subject to environmental changes, while its beach habitat is frequently being trampled by humans taking part in recreational activities on the beach. "Consequently, B. fonsecai is particularly susceptible to extinction," SNH scientists say.

Dave Jamieson says he's noticed fewer birds and bird species at his Bright's Grove dairy farm in recent years, and wants to know why. “They're just not around at all... I can go out all day and I'm lucky to see one,” he said, pointing to the disappearance of barn swallows (Hirundo rustica), chimney swifts (Chaetura pelagica) and other birds. “How come nobody notices these birds aren't around?” Jamieson, who has lived on the property all his life, said he used to see more than a dozen barn swallow nests at one time. “In the last three years, there's only been about four; and this is the first year they've never had babies,” he said. “Even when you drive along the road, and look at the hydro lines – where birds used to sit all the time – they're not there anymore.” Jamieson said he's so concerned, he's contacted Sarnia City Hall and the Ministry of Natural Resources office in Chatham, but hasn't received a response. But a biologist with Bird Studies Canada said Jamieson's concerns reflect new and alarming trends among Canada's bird populations. “There's a real dramatic change in the bird landscape going on in Canada,” said Jody Allair, biologist and science educator, pointing to a ground-breaking report released last year called The State of Canada's Birds.

Built on a fragile balance of predators and prey, Australia's various ecosystems are highly susceptible to change. When human intervention consistently alters an ecosystem, this balance can be upset, seriously threatening the biodiversity. While all species are important to an ecosystem, 'keystone' species are particularly vital. These are often top predators such as crocodiles, because of the role they play in controlling prey. The southern cassowary, however, is also a keystone species as it spreads the seeds of as many as 238 species of plants in northern Queensland. "Importantly, research clearly shows that biodiversity contributes significantly to our survival, well-being and enjoyment of life, so when we lose species at the rates that we're currently witnessing, we should be gravely concerned," says Dr Euan Ritchie an ecologist at Deakin University in Melbourne. "Losing any one species is a tragedy, but what is even more concerning is the loss of a species' ecological role following its extinction," says Euan. "If we were to lose dingoes, as an example, we also lose their ability to control pest species such as foxes and cats, and overabundant herbivores, [like] pigs, goats and kangaroos, which has widespread and often negative impacts across the whole system."