PEST CONTROL | PPC103 MAY 2021

At PestExtra 2021, Dr Bastiaan Meerburg gave a presentation on the impact that reducing rodenticide use had on the Dutch approach to rodent control.

SPEED VIEW:

• In the UK and the Netherlands, emphasis has moved from extermination to prevention
• IPM has many advantages but requires responsible citizenship and governments
• Government and councils avoid paying for preventative pest control measures, only taking action when forced
• No research on resistance in the Netherlands since 2012, leaving Dutch pest professionals with an outdated map
• Dutch policy changes from 2023 onwards: anticoagulants off-limits to non-professionals
• Digital monitoring technology helps IPM.

Dr Meerburg obtained his PhD in medicine from the University of Amsterdam in 2006, with his main focus being the zoonotic risks of rodents in livestock production.

As Director of the Dutch Pest and Wildlife Expertise Centre, and Senior Researcher at Wageningen University, he specialises in educating pest professionals about integrated pest management and advising the public.

Development of rodent management in the Netherlands

Dr Meerburg’s presentation began with a ‘then and now’ comparison of rodent control in the Netherlands and how it has evolved in pretty much the same way as here in the UK.

Where previously there was an emphasis on ‘exterminating’, now we approach rodent control within the principles of Integrated Pest Management (IPM). This is a shift in focus that has been necessary as attitudes, knowledge and regulations have changed.

Monitoring, early detection and habitat management play much more important roles in this new dynamic, says Dr Meerburg.

And when rodents are found to be present, you start your control measures, ranging from non-chemical to chemical.

• There are many advantages of IPM:
• Less environmental damage
• Reduced chances of secondary and
• non-target poisoning
• Improved animal welfare.

However, Dr Meerburg says that one of the main problems with IPM is that it requires “responsible citizenship and governments”.

“Rats and mice benefit from sloppy people,” he declares; a sentiment I’m sure we can all agree with.

An interesting take on pest management was his comparison to Sir Isaac Newton’s First Law (Law of Inertia). Sir Newton defined inertia as the resistance of any physical object to any change in its velocity, including changes to the object’s speed or direction of motion.

If an object is not moving, it will stay that way unless a net force acts on it. And similarly, if an object is in motion, it will remain in motion unless a net force acts to stop it.

Dr Meerburg believes the same is more or less valid for pest management.

Often you have a government that, most of the time, is happy to leave things as they are rather than spend money on preventative action when it comes to rodent control.

Then suddenly, when bins aren’t being emptied, or flooding happens, and the numbers of complaints are rising until there’s a lot of media attention, suddenly governments begin to take notice. That’s the net force that acts upon them to change their state of motion.

But unfortunately, those governments do not stay in motion. Once they’ve taken action and the rat numbers start to reduce again, they say, “Okay, this has worked so that we can stop now.”

Then suddenly, when bins aren’t being emptied, or flooding happens, and the numbers of complaints are rising until there’s a lot of media attention, suddenly governments begin to take notice. That’s the net force that acts upon them to change their state of motion.

They either don’t understand the value of preventative action, or they don’t want to invest in it because spending money on ‘nothing’ causes friction.

That’s the crux of public health issues like pest control because if we’re doing our preventative work right for our clients, it can look like money is being spent on something that they don’t see results for.

And this can be one of the biggest problems with IPM. It relies on both government and citizens taking a responsible, preventative approach.

Dr Meerburg says that in the Netherlands, there are four ministries at government level which have responsibility for pest control, which means that they often pass the buck to each other as nobody wants to take ownership of it.

Rodenticides

Issues with rodenticide resistance, which have formed over the years, are another reason for an increased interest in pest technicians implementing IPM.

Dr Meerburg praised the work of the Rodenticide Resistance Action Group (RRAG) on tracking the movement of resistance across the UK and mapping out the effectiveness of rodenticides.

He said that pest management professionals in the Netherlands are struggling to get the attention of a hesitant government on the subject of resistance.

Other than some information from a study carried out in 2012, which gave professionals a snapshot of the resistance situation at that particular time, there’s been no further work on the topic.

Unfortunately, sending samples in for rodenticide testing now is costly, a huge drawback for pest professionals and those who hire them, which is why the resistance situation in the Netherlands is largely outdated.

However, even with old information, the mapping of areas of resistance (like we do in the UK) has enabled pest management professionals in the Netherlands to utilise IPM when controlling rodents in high resistance areas.

Dutch policy since 2014 has aimed to ensure that untrained people use fewer rodenticides, however in practice, it didn’t appear to work. In 2017, research by the National Institute for Public Health and the Environment showed that non-professionals used just as many rodenticides as in the years before Dutch policy changed.

Moreover, they saw that these rodenticides were often not well applied. Almost half of the people they interviewed admitted to not reading the labels and did not know that only licensed pest controllers can use rodenticides against rats in the Netherlands.

Dutch policy is changing so that from 2023 onwards, anticoagulants will be completely off-limits to non-professional users. Although rodenticide use by non-professionals has its own issues, there are also worries that rodent numbers will increase because of a lack of knowledge around traps and neophobia.

There are also no rules or regulations around how traps are made in the Netherlands, which often means traps aren’t strong enough to successfully or humanely control rodents.

There are also issues with an unwillingness to hire a professional. From research carried out, only two per cent of the people interviewed hired pest controllers to deal with mice, and if they had rats, only 20% hired a professional.

Acute poisons are an ages-old mainstay for rodent control. Single feed baits like zinc phosphide are still quite common in some parts of the world, such as India. It’s a rodenticide for single uptake, and the rodent dies one to three days after ingesting it because the stomach’s acid reacts with the phosphide and a toxic gas emerges. As with all single baits, there are major disadvantages, especially concerning bait shyness, because rodents can link the death of their fellows with the bait. You also have non-target poisoning, and this is something that is also really problematic in India. Not only are there a lot of accidental poisonings, but also people commonly use these types of poisons to commit suicide or murder. These types of poisons have very high mortality rates.

Future of IPM

Dr Meerburg shared his final thoughts on new digital monitoring technology, which he believes will help facilitate IPM effectively as we move forward.

“We educate pest controllers in the Netherlands on IPM, and we have specific training on new digital technologies, like thermal imaging.

“IPM is crucial, and there’s so much modern technology to help get rid of rats.”

As pest management professionals, the best thing we can do regarding reducing rodenticide use and using IPM is to share our expertise with customers and the general public, and where possible, your local council or members of parliament.

You’re the expert, and you know that preventative measures, habitat management and monitoring are the first and best line of defence, so share that knowledge where you can.

Did you miss the show?

If you didn’t catch Dr Meerburg’s presentation at PestExtra, you can watch it in full on our website.

bpca.org.uk/cpd-videos

Source: PPC103