Invasive Species, Natural Disasters Of Our Own Creation

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Who needs horror movies when a story like this makes for much more compelling fear, and the realism is, well, real. Click the image above to go to the story:

Biosecurity ‘weaponry’ is helping to halt the global spread of non-native species, from rampaging caterpillars to giant hornets

The best time to annihilate oak processionary caterpillars is when they are young, just a few millimetres long and still high up in the trees. At this stage, their appetite for oak is rapacious, so dousing the leaves in a biocontrol agent like Bacillus thuringiensis (Bt) is one way to get the caterpillars to ingest it. When Bt toxins dissolve in the caterpillar gut they become active, puncturing the stomach and killing the insect in several days.

Craig Harrison, of the UK’s Forestry Commission, explains this to me one bright spring morning in a south London wood of bluebells, brambles and oak. We have come to the front line of UK biosecurity control to watch two contractors in biohazard overalls manoeuvre a quad bike with a big red blower on the back around the wood. Every so often they park the quad, aim the blower at the trees and spray. “Money-wise and in terms of resources, oak processionary is the biggie,” Harrison says. A mist of certain caterpillar death wafts through the canopy.

Oak processionary moths (OPM) and their caterpillars have no natural place in an English wood. They are an invasive non-native species from southern Europe unwittingly introduced to the UK in 2005 — and one in thousands of species worldwide that have been scattered by humans around the globe to disastrous ecological effect.

Ecologists liken the introduction of a non-native species to Russian roulette. Most often, an insect transported in a tourist’s suitcase to an alien environment will not survive — perhaps it can’t find food or gets eaten itself. Occasionally, though, a beetle stowed in wooden pallets shipped from China will face few of the predators that had once kept it in check. It will find plentiful food and a mate and become “established”. And then it will spread.

In recent decades, as global trade and mass transit have bloomed, the great global reshuffling of flora and fauna has accelerated. It is estimated in any 24 hours 10,000 different species, such as molluscs, crustaceans, seaweed and plankton, are moved around the world in ballast water. “We’re talking about the widespread redistribution of life on earth — there’s no precedent in the fossil record,” says Anthony Ricciardi, a biological invasions specialist at McGill University in Montreal. The International Union for the Conservation of Nature calculates that invasive species are the second most significant threat to biodiversity after habitat loss.

If we have been slow to grasp the destruction that mass species dislocation can reap, we are at least getting better at handling it. Our advancing understanding of biosecurity “weaponry” — from tree genetics and biocontrol to GM technology — is helping to both manage existing incursions and prepare for future threats.

There is now little chance the UK will be rid of OPM completely; the bug has established itself in west London and is fanning out through the south-east. The caterpillars are noticeable from May until July when they grow defensive, toxic hairs and crawl in nose-to-tail “processions”. As well as damaging trees through defoliation, they threaten human health as when touched, the hairs cause rashes.

The history of biocontrol — where predators, parasites or pathogens are released into a habitat to bring an invasive under control — is potted with high-profile failure and ecological calamity. When Australia introduced cane toads to control sugarcane beetles in Queensland in the 1930s, the toads swarmed the country, wiping out indigenous fauna. Harlequin ladybirds, a native of Asia introduced in Europe to control aphids, are thought to have reduced the UK native population of two-spot ladybirds by 44 per cent in the past decade. (As well as being voracious aphid-eaters, harlequins are cannibals.)…

Read the whole article here.

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