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Move over Godzilla: sap-sucking lice are the latest invaders from Japan

March 30, 2010

The Government has announced that a sap-sucking louse from Japan will join the ranks of non-native species in the UK.

Following a consultation period, the innocuous-seeming insect, Aphalara itadori, is being released into the wild as a way of keeping that gardener’s bugbear Japanese knotweed in check.  Apparently it has a liking for this pernicious weed, feeding on its sap and stunting its growth, but doesn’t fancy much else in the plant kingdom.

However, the danger is that nature always seems to find a way of adapting to new environments, and the price of this critter making itself at home in the UK countryside might be paid by other organisms.  While the scientists will have looked at all the scenarios, there might be a scenario unexamined because unthought of.

As an example of the problems that can arise, consider Harlequin ladybirds.  These were introduced to Britain a few years ago as a similar biological control – to tackle aphids.  Many of our 46 native ladybird species are now losing out to these American (originally Asian) arrivals in the hunt for food, and are also being eaten themselves.  Attempts are being made to monitor the progress of these invaders with a view to eradicating them before it is too late to do so. 

The best-known example of a deliberately-introduced animal is the grey squirrel, which arrived in the 1870s.  Few (especially red squirrels) would disagree that we would have been better off without it. 

Ring-necked parakeets do not pose a major problem yet, but may do if their numbers increase further.  These birds have been popular pets since Victorian times, and escapees have thrived in parks and suburban gardens despite the British winter weather.   It was only in the late 1960s that they started to breed in the wild: they are most numerous in London and the South East, but have now reached Wales and the Scottish borders.

The Ruddy Duck, a native of the Americas, was added to wildfowl collections in the 1950s but has established populations in various parts of England.  In this instance, the unwelcome consequence is its tendency to mate with the European native white-headed duck, an inhabitant of Spain and the eastern Mediterranean.  Tackling the issue here in the UK is seen as an essential means of addressing a threat to the biodiversity of our continental neighbours, and hence the Defra-funded eradication programme. 

Looming in the background is the complicating factor that is climate change, as it could enable non-native species to thrive at the expense of natives, and also lead to unexpected changes in behaviour.

A further non-indigenous species is the wallaby.  It is more noticeable (if you happen to come within range of one) and more photogenic than a Japanese insect, and fortunately not a threat to local flora and fauna.   There is a wild population in Ashdown Forest, near SolarUK’s current office.

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