Scotland’s rats are showing signs of growing resistance to poisons commonly used to keep their numbers in check – while Brexit clamps down on tools used to keep pests in check.
Scots taking on home solutions to ensure their homes are pest free could be making the issue worse, as they could be unwittingly “killing only the non-resistant rodents leaving the resistant ones to breed”, British Pest Control Association (BPCA) president Chris Cagienard revealed.
Brexit is also impacting the tools pest controllers have readily available to tackle vermin as less companies opt to pay to put their products through UK-specific regulation processes.
“Our toolkit continues to get eroded,” Mr Cagienard said. “It raises questions of are we going to get the toolkit to be able to do the job or are people going to be more willing to coexist with rodents.”
The warning comes as pest control visits facilitated by Scottish councils grew from 36,995 in 2020/21 to 45,918 in 2021/22, freedom of information requests to all local authorities revealed.
This increase was largely due to a drastic increase in wasp callouts based on the 22 councils that provided data for visits to deal with the insect’s nests, which spiked from 5685 to 10,628.
Orkney and the Western Isles councils do not provide pest control visits, while East Lothian council was the only authority to not respond to the request for information.
Of the councils which broke down the callouts into totals for rats, the most treatments for rats from July 2021 to June 2022 were seen in North Lanarkshire with 3657 visits, Fife with 2278 and South Lanarkshire with 1117. Glasgow City Council could not provide a break down per type of vermin.
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Based on cumulative totals of visits for both rats and mice, only eight out of 28 councils saw numbers of visits rise from 2020/21 to 2021/22 – North Lanarkshire (64.69% rise), East Ayrshire (1.30%), Aberdeen City (36.11%), South Ayrshire (52.25%), Stirling (500%), Midlothian (55.10%), Perth and Kinross (28.95%) and Aberdeenshire, which went from no pest control visits to two visits for rats.
Lockdown saw rodents search our homes for food
However, the decline in rodent pest visits in homes across other councils is likely tied to the end of lockdowns – as Scots returned to city centres, so did the rodents.
Mr Cagienard, who is also the managing director at Pest Solutions which provides services across the country, said that “when our behaviour changes, rodents’ behaviour changes” too.
“Rat populations in the UK are not reducing, they are climbing slowly anyway and that was happening before Covid and that continues to happen,” he said.
As the lockdown saw less people in the city centres and pubs and restaurants forced to close, in some cities multiple times from July 2020 to June 2021, rodents had less sources of food within the city.
“It wasn’t necessarily that there were more rats, there were just more rats within the houses. “
BPCA technical officer John Horsley said: “Work from some data scientists who correlated call outs pre-pandemic and from the pandemic onwards did see an increase in home call outs once we went into lockdown.
“That was to do with their food source, which would normally be found in the city centre, in restaurants’ bins for example. But once that all closed, they needed to find a food source.
“Many would have probably moved out of town to go find that food source in people’s gardens and places like that.
However, he added: “We don’t get thousands of mice and rats flooding people’s homes. It’s fairly stable.”
‘More resistant’ and ‘more of an issue’
Nevertheless, a growing “complication” for pest control technicians is the emergence of chemical resistance in certain rodents in Scotland.
“There is a lot of products that we are starting to see resistance to,” Mr Cagienard warned. “In certain areas of the country these products don’t have an effect anymore, so we need to be careful.
“Usually, a professional pest controller would be aware of this and use other products accordingly.”
However, do-it-yourself pest control “where people are just buying stuff from B&Q and putting it down” could leave the resistant rats to breed “meaning they are becoming more resistant and becoming more of an issue”.
Mr Cagienard added: “That is the concern. Effectively we are breeding more resistant rats because people aren’t aware of the problem.”
Pest solutions is now one of the companies actively sending samples of rats they believe may be showing signs of chemical resistance to the Animal and Plant Health Agency for testing.
Of the samples that have been successfully tested over the past six months, only one was returned as non-resistant.
Chemical resistance is just part of the problem, and some cities are also experiencing “behavioural” changes which has been growing more severe in the past ten years.
“We’re also seeing a lot of changes in behaviour especially in urban environments,” Mr Cagienard said.
“For mice in cities like Glasgow, in particular, there is a lot of behavioural resistance, so they are basically learning to evade the control measures.
“That’s progressed considerably in the past ten years.
“There is a lot of training and learning required to make sure pest controllers have the knowledge to overcome this situation.”
Residents are not helping the situation themselves either, with littered food posing a more attractive option for rodents over bait.
“Because we are a nation that loves to drop litter there is always a lot of competition for food,” Mr Cagienard said about controlling city rodent populations. “Rodents are going to go for the kebab over the bait.”
Pest control’s ‘eroding’ toolkit
While there are not massive increases to rodent numbers due to the UK’s relatively mild climate, Mr Cagienard warned the underlying rat population “is increasing” because the tools and chemicals they would use are being pulled out from the UK market.
While businesses distributing these products previously only needed to pass regulation at EU level, post-Brexit they now have to go through another regulation process to sell in the UK.
He said: “It is becoming less economically viable for the companies to get them regulated in the UK.
“Unfortunately, the threat that is at our door is taking away all the products and leaving pest controllers with just snap traps.”
The BPCA president warned that this is not only “more laboursome” but also “inhumane”.
“These traps aren’t regulated and hence the ones available for DIY use aren’t strong enough to kill and you end up with maimed animals rather than humane kills.”
Upcoming Scottish Government plans to ban glue traps are also a concern for some pest controllers.
The boards have been criticised by animal rights including the Humane Society International (HSI) due to the “agonising” death it may cause to rodents, and other animals that get stuck for long periods of time.
However, Mr Cagienard emphasised that professionals using the boards know the risk they post and will check them regularly as well as accounting for each one that was placed.
He said: “If you have a rat where it is just unacceptable to have a rat like hospital operating theatres or a restaurant kitchen, you can physically remove that rat really quickly. The problem is that these tools are also available to the DIY market.
“The professional use of glue boards can be done very, very humanely, but the problem is the public are just buying these then putting them down and just forgetting about them.
“The rodents are going on them and then dying of stress or shock or starvation. That is a cruelty beyond comprehension and something that should be prosecuted.
“Us pest controllers have a reputation for being cold blooded killers but most of us are animal lovers and that couldn’t be further from the truth.”