Vlinders

Erik Runquist saw it for a moment, then it was gone. Walking a tract of Nature Conservancy-owned prairie outside Moorhead, Runquist caught a glimpse of a Dakota skipper (Hesperia dacotae), a thumbnail-sized, orange and brown butterfly. It perched atop a coneflower before disappearing into the prairie grass. "Skippers are evasive. You may get only a few seconds to be able to find it before it zips off the coneflower, especially if it's a windy day," said Runquist, the Minnesota Zoo's butterfly conservation biologist.

Human disturbance negatively affects the pollination and seed dispersal of forest trees -- an effect that can be observed in both tropical and temperate forests. This is the key result of a synthesis of 408 studies from 34 countries around the globe. In the long term, less pollination and seed dispersal is likely to reduce the ability of forests to natural regenerate. The researchers investigated all processes in the plant regeneration cycle and specifically asked how much they are each affected by humans.

Menschliche Eingriffe wirken sich negativ auf die Bestäubung und Samenausbreitung von Bäumen und anderen Waldpflanzen aus. Verantwortlich ist in erster Linie der Rückgang der daran beteiligten Insekten, Vögel und Säugetiere. Damit verringert sich langfristig die Möglichkeit des Waldes, eigenständig nachzuwachsen. Bestäubung und Samenausbreitung von Sträuchern und Bäumen basieren fast ausschliesslich auf Tieren. Dieser Effekt ist sowohl in tropischen Wäldern als auch in Wäldern der gemäßigten Breiten beobachtbar.

Johannes Steidle ist tief besorgt: „Bei unseren Untersuchungen im Freiland haben wir in diesem Jahr bisher nur beängstigend wenige Insekten gefunden“, berichtet der Biologe, der am Institut für Zoologie der Universität Hohenheim das Fachgebiet Tierökologie leitet. Heuschrecken beispielsweise haben die Hohenheimer Ökologen bisher kaum entdeckt. Aber auch andere Insekten machen sich ungewöhnlich rar: „Wenn ich durch den Hohenheimer Park gehe, komme ich mir vor wie auf einer nächtlich leeren Autobahn: Wo sind die Insekten?“, fragt sich Steidle.

You do not need to be a naturalist to love butterflies. Dolly Parton sings about them. So does Miley Cyrus. Tracy Morgan says he used to be an angry young man in a cocoon, but “now I’m a beautiful black butterfly.” And the poet Robert Frost once celebrated the “blue-butterfly” days of spring. But hold the lyrics. The butterflies are vanishing, according to an article in this week’s edition of the journal Science, and it’s happening even in protected areas.

Summer is expected to be a flowery, colourful time of year in the garden with butterflies fluttering from one blossom to another. However, if you're a bit of a butterfly boffin, you may have already noticed that there have not been too many of them around this year. The Wall Brown, which has already been in steep decline in recent years, has not been spotted at all this year. This is also the case for four of the other resident species, Purple Hairstreak, Silver-washed Fritillary, Clouded Yellow and Grayling.

Erik Runquist saw it for a moment, then it was gone. Walking a tract of Nature Conservancy-owned prairie outside Moorhead, Runquist caught a glimpse of a Dakota skipper, a thumbnail-sized, orange and brown butterfly. It perched atop a coneflower before disappearing into the prairie grass. "Skippers are evasive. You may get only a few seconds to be able to find it before it zips off the coneflower, especially if it's a windy day," said Runquist, the Minnesota Zoo's butterfly conservation biologist. "Once they get in flight, it's almost impossible to find them again.

A new study by the Xerces Society showed a 74 percent decrease in the number of monarch butterflies (Danaus plexippus) over the last two decades. Butterfly conservationists at the Pacific Grove Museum of Natural History monitor the monarch numbers on the Monterey Peninsula and said the study's results come as no surprise. They are similar to a trend conservationists are seeing locally. Their numbers are going down," museum representative Patrick Whitehurst said. Whitehurst said that between 2014 and 2015, the monarch population at Pacific Grove's sanctuary was cut in half.

Insect populations are declining dramatically in many parts of the world, recent studies show. Researchers say various factors, from monoculture farming to habitat loss, are to blame for the plight of insects, which are essential to agriculture and ecosystems.