TECHNICAL | PPC100 August 2020

In our 100th edition of PPC, regular contributor Clive Boase reviews how far the pest management industry has come since PPC first launched and, critically, where he thinks the industry might be in another 25 years. Stay tuned for PPC200 to see if he’s right! 

At first sight, the UK pest landscape may not appear to have changed much in the last quarter-century. Pest controllers have always been busy with rodents, together with wasps and ants in the summer, a few housefly problems, and maybe some bed bugs and cockroaches in town. However, first appearances can be deceptive.

A closer look will reveal that there have been dramatic changes underway. It’s not that we haven’t noticed them individually, but it’s only when we stop to look over our shoulders that we realise the cumulative extent of all these changes.

Of particular interest is the wide range of reasons driving these changes (see table).

We tend to think of importation of pests as being the main drivers, but many of our upcoming pest problems are actually homegrown. 

Drivers for change

In some cases we see native species that formerly would have avoided urban areas, now adapting to the urban environment.

On the one hand, this is a wildlife success story, but on the other, there is also the potential for conflict with residents.

Some of this adaptation started more than 25 years ago, with foxes being an obvious example. However more recently, we now see deer causing issues in the suburbs while, among the smaller vertebrates, the wood mouse (Apodemus sylvaticus) is an interesting case.

Most pest control books do not mention this as an indoor pest, but feedback from some pest controllers suggest that this has now become a dominant indoor pest in several areas. Once in buildings, it appears capable of displacing smaller house mice.

In the bird world, herring and lesser black-backed gulls have also become increasingly urbanised in recent decades.

Sometimes it’s not the pests’ behaviour that has changed, but their physiology. The classic example is the bed bug. In 1995, this pest was uncommon in residential properties, occurring in a few inner-city areas only, while the hospitality industry considered it to be extinct. However, over the following decade, it has surged back to prominence.

It has developed resistance mechanisms to several insecticides, making it more challenging to eradicate and allowing it to spread.

In other cases, changes to legislation have altered the status of pests. For example, the Landfill Tax was introduced in 1996 to reduce the volume of waste going to landfill by stimulating the recycling industry. The Act has been successful, with many of the old landfill sites now closed, but instead we now have waste management companies located on industrial parks, often close to residential areas.

As a result, houseflies spilling out of these waste sites into homes has become a growing problem.

Despite border checks and phytosanitary precautions, pests from overseas are still being accidentally imported into the UK or mainland Europe. Many of these imported pests lack natural predators in this country, and can therefore spread very rapidly.

Obvious examples would be the Asian hornet (first reported here in 2016) which, although it is not yet permanently established on mainland UK, has been found on several occasions.

The harlequin ladybird (first reported here in 2004) spread across England and Wales in a few years, impacting on native wildlife, as well as hibernating in numbers in buildings.

The garden cockroach (Ectobius vittiventris), first reported here in 2018, is already established in numerous separate locations and is causing confusion with the German cockroach.

The invasive garden ant (Lasius neglectus) was first found here in 2009 but is already established at a number of locations from Yorkshire southwards.

Finally, the tiger mosquito (Aedes albopictus) was accidentally introduced to Europe in the 1970s and has been steadily spreading since then. This mosquito is a particular concern because it is a vector of several human diseases, including dengue and chikungunya, causing outbreaks in several European countries.

It was first detected in the UK in 2016, and there have been several incursions since. Fortunately, so far, it appears to have been eliminated on each occasion.

However, climate change is possibly the most significant background development in the UK (and globally), with the top ten hottest summers all occurring since 2002.

This has allowed southern European species, such as the tree bumblebee (Bombus hypnorum) to move north and colonise the UK.

This species was first recorded here in 2001 and is now widespread. It prefers to nest in cavities in buildings and in bird boxes, so sometimes comes into conflict with residents.

The ivy bee (Colletes hederae) has also drifted north to the UK in the last 20 years, creating problems when excavating nests in lawns and flowerbeds.

Finally, it would be a great reflection on the pest control industry if this article also had a lengthy section covering all the pests that have been eliminated from the UK in the last quarter-century.

Sadly, the last major pest to be completely eradicated from the UK was the coypu, and that was in 1989, so six years too early for this article.

Insect imports

If we look at the imported pests that have become established in the UK, an important pattern stands out. Most of our classic indoor pests, such as the German cockroach, the confused flour beetle, the Indian meal moth and the pharaoh ant, all arrived here long ago.

During the Victorian era, international trade brought in goods and pests from the colonies, and our indoor environment was by that time suitable for these warmth-loving species.

By contrast, our outdoor environment back then was suitable only for the native insects that had already been here for millennia, such as the common wasp and the garden ant.

However, with the advent of climate change in recent decades, our outdoor environment has started to warm. As a result, we are now seeing a second wave of pests; but this time they are outdoor-living pests such as the tree bumblebee, the harlequin ladybird, the invasive garden ant, the garden cockroach, the false widow spider, and many others that are taking advantage of our milder outdoor conditions.

The next 25 years

Without a doubt, the most important driver for change in the next 25 years will continue to be climate change. Even if radical mitigation measures are introduced soon, which seems unlikely, global temperatures will continue to rise for a while yet.

We do not know exactly what effect this will have on our pests, but we can obtain a rough idea by looking at the pest situation further south in Europe.

Several species may take advantage of climate change, and move northwards.

Termites are widespread in France, with one species, Reticulitermes flavipes, already being established as far north as Rouen. They can cause serious damage to structural timber and, because they disperse with a swarming flight, it would seem possible for this species to cross the Channel and become established here in the next 25 years.

The tiger mosquito (Aedes albopictus) is another obvious candidate for colonisation within the next 25 years, with climate studies showing that large areas of the UK are becoming suitable for this species. Vector-borne disease may once again become a reality here.

Finally, a long shot, phlebotomine sandflies are present in most southern European countries. They are responsible for the transmission of leishmaniasis, a disease of dogs, rodents, and of people. Climate change may see them drift northwards, and threaten the UK.

The extent to which incoming species become established or are eradicated in the next 25 years will also be affected by the political response to this problem.

In 2015, the Infrastructure Act was passed which allows environmental authorities to issue species control orders. These orders can be used to require landowners to eradicate specified species from their land or allow the works to be carried out.

It remains to be seen how often these useful powers are actually put into practice.

And finally, it would be wrong and incomplete to write an article in mid-2020, without mentioning the Covid-19 pandemic.

If this pandemic teaches us one thing, it is that the unexpected can and does happen, sometimes with devastating and tragic consequences.

How often have we heard of pest problems elsewhere and thought: that couldn’t possibly happen here?

Just as healthcare experts were looking with concern at the disease outbreak in China in early 2020, our industry should also be looking hard at pest problems elsewhere, and be making contingency plans.

It may only be a matter of time before these pests arrive on our shores, and we need to be ready, in terms of knowledge, skills and resources. It may then be our turn to be on the frontline.

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Source: PPC100