Overige insecten

Mammals, along with birds, reptiles and amphibians, are an extremely small percentage of all biodiversity (~0.4%). Invertebrates on the other hand, make up the vast majority of biodiversity (~80%) but feature such unloved creatures as leeches, parasitic worms, spiders, snails, lice and aphids. The most insidious threat to invertebrates is that we haven’t documented their diversity. For most invertebrate groups, we don’t know what species are out there and therefore struggle to identify those that are threatened. The specific consequences of neglecting invertebrates in land management are largely unknown. But these creatures perform key functions within ecosystems, from pollination to controlling population explosions of other species of plant and animal. Invertebrates recycle waste; without dung beetles for example, we would be hip-deep in manure. Pollination by insects helps plants cross-pollinate and produce viable seeds, resulting in fruit, grains (such as wheat and canola) and honey. Without invertebrate pollination we would lose countless species of plants including the majority of orchids. Invertebrates provide a vast food supply for the survival of other invertebrates (spiders, scorpions, tiger beetles), vertebrates (lizards, frogs, birds, bats, fish, insectivorous mammals) and some plants (carnivorous plants). There has even been talk of edible insects being introduced to the western diet for their health and environmental benefits. As the famous entomologist EO Wilson notes, invertebrates are “the little creatures that run the world”; without them, all life “would mostly disappear … within a few months”.

All around him, even in a place as beautiful as the Little Qualicum River estuary, his office for 30 years as a biologist for the Canadian Wildlife Service, he sees the unravelling of "the web of life." "It's happening very quickly," he says. Registered Professional Biologist Neil Dawe has written over 80 papers on birds, ecology and the environment. He received Environment Canada's Regional Citation of Excellence Award for his work in co-founding and co-chairing the Brant Wildlife Festival. He received the Outstanding Service Award from the Federation of B.C. Naturalists and the Ian McTaggart-Cowan Award of Excellence in Biology from the Association of Professional Biologists of B.C. In 2006, he retired from the Canadian Wildlife Service, Environment Canada, after 31 years of managing National Wildlife Areas and Migratory Bird Sanctuaries on Vancouver Island. He is President of the Qualicum Institute: www.qualicuminstitute.ca.

Neonicotinoid insecticides have adverse effects not only on bees but also on freshwater invertebrates. An Eawag study published today in the journal PLOS ONE (Public Library of Science) shows that at least one of the insecticides in this class also has toxic effects on freshwater invertebrates. In this study, native freshwater shrimps (gammarids) were exposed to pulsed high and to constant low concentrations of imidacloprid. Peak concentrations typically occur when rain falls on farmland during or shortly after the application of insecticides; these soluble but persistent substances can then enter surface waters via runoff. Interestingly, pulses lasting no more than a day proved less harmful to the organisms than concentrations that were much lower but persisted for several days or weeks. While organisms transferred to clean water after pulsed exposure recovered relatively rapidly, constant exposure led to starvation after 2 to 3 weeks. This was because the organisms' mobility and feeding behaviour was impaired by the neurotoxin.

Nach einer aktuellen Untersuchung der NABU-Naturschutzstation Münsterland wurden im Kreis Warendorf und der Stadt Münster in den letzten drei Jahren dramatisch weniger Kiebitzpaare (Vanellus vanellus) gezählt. 2011 gab es nach Angaben von Kristian Mantel auf landwirtschaftlichen Flächen in Münster noch 110 Kiebitzpaare. 2013 seien es lediglich noch 62 Paare, sagte der Vogelexperte der Station. Wenn sich nichts ändert, sind sich die Naturschützer sicher, stirbt der Vogel bis 2030 aus. In einem Beobachtungsgebiet im münsterischen Stadtteil Wolbeck hätten 18 Paare gerade noch drei Küken durchgebracht. Das ist „gespenstisch“, sagte Mantel. Ähnlich sei die Situation im Kreis Warendorf. Die Fachleute des Nabu haben ausgerechnet, dass pro Brutpaar und Jahr nur noch 0,16 Küken überleben. Damit der Bestand erhalten bleibt, sind aber 0,8 Küken pro Paar notwendig.

The nine-spotted beetle is a ladybug beetle who gets her name from the nine spots on her wings. Until the mid-1970s, the nine-spotted beetle was one of the most common ladybug beetles. To the delight of farmers that welcomed the fact that these beetles ate pest insects such as aphids, nine-spotted beetles were prevalent on farms. However, they suddenly began to disappear in large numbers. Though the nine-spotted beetle was once common throughout the United States and in southern parts of Canada, other beetles such as the seven-spotted lady beetle and various Asian beetle varieties have moved into these areas, creating competition for food. Like the nine-spotted beetle, the invading beetles feed off the same insect food sources, including aphids, mites and leaf hoppers.

The intensification of agriculture could have an impact on threatened populations of farmland birds due to its effect on one of their most important food sources, the sawfly. In the first genetic study of farmland sawflies in the UK, scientists at the James Hutton Institute in Dundee examined the genetic diversity and population structure of sawfly larvae at a number of sites in Scotland in order to gain a better insight into agriculture’s impact on sawfly abundance. Their study provided the first evidence for the presence of diploid males in UK farmland sawfly populations. Diploid males are usually sterile and are typically produced when an unusual form of sex determination, called complementary sex determination, operates in inbreeding populations. Their study suggests that farmland sawflies might be vulnerable to population decline due to low levels of genetic diversity and inbreeding.

Among the various insecticides tested on the grubs of lady bird beetle, Cryptolaemus montruzeiri, buprofezein, azadirachtin and dichlorvas were found to be the safest causing minimum per cent mortality of 33.33, 34.44 and 48.89 per cent respectively. However, highest mortalities of grubs were recorded in imidacloprid, carbaryl and acetamiprid recording 96.67, 92.22, 91.11 per cent mortality of grubs respectively. Buprofezin 25 EC @ 0.01% and azadirachtin 0.03% EC were found safe for adults recording 10.00 and 13.33 per cent mortality, respectively while highest adult mortality was recorded in carbaryl (97.38%) followed by acetamiprid (93.33%) and imidacloprid (92.22%).

Ladybirds are well known beneficial arthropods found in many habitats and ecosystems. They feed on various kinds of pest insects. In fact, coccinellids during their adult and larval stages attack on a variety of soft bodied herbivorous pests, including aphids, whiteflies, psyllids, and scales. Moreover they ingest fungal spores, pollen and nectar as complementary or even alternative foods when the preys are rare. In this study, the influence of sublethal concentrations (LC10 and LC30) of a neonicotinoid insecticide, thiamethoxam, was evaluated on life parameters of Hippodamia variegata Goeze (Coleoptera: Coccinellidae), Results showed that thiamethoxam changed life expectancy, and declined age-specific fecundity. The insecticide decreased preadult development time significantly, but it didn't have any effect on adult developmental period. Also, Eggs fecundity and fertility were not changed by treatments. According to this study, more care should be taken when thiamethoxam is used in IPM programs.

One of the great mysteries of the insect world right now ranking up there with the loss of winged pollinators in general is what has happened to North America's native ladybug species? About 20 years ago, they started to "fly away" just like the nursery rhyme. There are still ladybugs to be found; but, the chances are they are not native ladybugs. Invasive ladybird beetles now account for two-thirds of all ladybugs in the United States and Canada. Other countries are faring no better. The UK is suffering a serious invasion of Harlequin ladybugs. These aliens are taking over and pushing out the native species there as well. Many more countries are fighting their own battle with invasive alien ladybird beetles.