Mutant rats plague Hampshire

6:10am Sunday 12th October 2008

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By Peter Law »

MUTANT super-rats immune to normal poisoning techniques are swarming Hampshire, according to one of Britain’s leading rodent experts.

The revelation comes as a survey of councils reveals the number of rats infesting Hampshire has skyrocketed in recent years.

The pesky rodents are also proving a costly menace, with spending soaring by more than £40,000 in one borough.

DNA tests on rats collected across the county confirmed the presence of a mutant gene that helps rodents develop the resistance.

Professor Robert Smith, a scientist at the University of Huddersfield, made the claim after extracting DNA from the tails of at least 20 Hampshire rats earlier this year.

After conducting molecular tests on the tips of the tails, he said they all contained the same resistant gene mutation.

The super-rats are stronger thanks to an ability to resist the usual kind of anticoagulant poisons laid out to kill off the pests by exterminators.

With extended exposure to poison, resistant rats breed while others die off, leaving a resistant population. Individual rats do not develop resistance but are either born with it or not.

Prof Smith – who is mapping rat resistance in England – said: “Every one of the 20 or so Hampshire rats that we have tested carried either one or two copies of a resistance mutation known as L120Q.

“I cannot tell you exactly where these rats were collected because they were provided with the proviso that we would not reveal locations, but they were towards the middle of the county.”

Prof Smith said the near indestructible rats had been found in almost all parts of Hampshire, but he had yet to study specimens from Southampton.

However, he has no doubt they are spreading and said it was only a matter of time before super-rats marched into our cities and invaded our neighbouring counties.

A survey of councils in south Hampshire this week showed the rat population is booming.

New Forest District Council has seen the biggest rise, with its environmental health team called out to deal with 1,394 rats in the past financial year – a rise of 25 per cent since 2004.

Southampton City Council’s rat call-outs shot up 21 per cent to 995 rats, while Winchester City Council has seen a 12 per cent rise (2,798 rats) and Test Valley eight per cent (2,682). Eastleigh Borough Council was unable to provide statistics for 2007.

The population boom was put down to wetter summers, which helps the breeding cycle and over-feeding of birds by the public, but onlyWinchester said it has seen an increased resistance to pesticides.

Spending has also soared, with Test Valley dishing out £217,796 in taxpayers’ money, compared with £176,889 three years ago.

Prof Smith’s findings were supported by SeanWhelan, from Southampton-basedWhelan Pest Control. MrWhelan told the Daily Echo he believed any rats north ofWinchester were now immune to regular poison.

“North ofWinchester the bait we are using is stronger than the bait we are using in, for example, Romsey. The bait is pretty strong stuff, we are talking about something that could harm humans,”

he said.

“It’s only a matter of time before the rats in Southampton also show resistance to the bait.”

Professor Smith, who is a member of the UK Rodenticide Resistance Action Group, said the super-rats must be treated as a major public health risk.

“Rodenticide resistance is a matter of concern at the level of a Government department or departments. The trouble is that no Government department will take responsibility,” he warned.

“We know that rats carry and transmit a number of diseases that affect both humans and farm animals. These include diseases as serious as salmonella and leptospirosis.”

The poison needed to kill super-rats is so toxic it can only be used indoors, because of the risk it poses to wildlife.

So many exterminators must resort to trapping, a far less effective method.

Prof Smith said poisoning rats should be a last resort, rather than the first measure people think of.

Clearing up Hampshire’s streets and making life difficult for the super-rats would be the most effective form of treatment.

“Clearing up the urban environment can make a tremendous difference – getting rid of both the food waste and the piles of rubbish in streets and gardens that attract rats and give them somewhere to live will take away what rats need to settle and thrive.

“Using ineffective rat poisons makes the problem of resistance worse – by killing the susceptible rats but not the resistant ones, pest controllers selectively favour resistant rats and the genetic mutations that confer resistance will spread through a population.”

Rat stats

■ The average lifespan of a rat is 18 months ■ One pair of rats can produce a colony of 2,000 in just one year ■ There are an estimated 60 million rats in the UK – one for every person. Most of them are brown rats ■ Rats are scrupulously clean. They spend hours every day carefully grooming themselves and each other ■ Rats’ front teeth grow 4.5in to 5.5in each year. They wear them down by gnawing on materials such as cement, brick, wood and lead pipes ■ A rat can tread water for three days.