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13 May 2021

Climate change pests: critical pest species for the next 20 years

PEST CONTROL | PPC103 MAY 2021

As temperatures rise in the UK, Clive Boase, of The Pest Management Consultancy, looks at some of the invasive pests you might have to learn to manage in the future.

climate-change-pests-main

Is the invasion over yet?

Centuries ago, the job of a UK pest controller would have been much simpler.

At that time, the majority of the pests that we now depend on for a living, such as rats, house mice, grey squirrels, rabbits, cockroaches, storage insects and tropical ants had not yet arrived in the UK.

However, over the centuries, one by one, all these pests have gradually been introduced.

As a result, UK pest control is now largely an ongoing campaign waged against invasive pest species.

These invasive species have a very wide range of impacts.

Some damage buildings or infrastructure, some impact food production, some spread disease, while others attack or displace native wildlife.

Across the UK, looking at agriculture and forestry as well as pest control, invasive species are estimated to cost the UK a total of around £1.7billion per year.

Tiger mosquitoes

Colouring Black body with one white stripe down the back and silvery-white bands on legs and thorax.
Size  <10mm
Habitat Lay eggs in moist areas just above the water’s surface, such as tyres, birdbaths, animal dishes and flower pots.
Behaviour An aggressive biter that feeds throughout the day on a range of hosts including humans, pets and wild animals.
Life cycle Egg, larva, pupa and adult. Asian tiger mosquitoes can lay up to 500 eggs in their lifetime.
Adults are usually found near their breeding area. Eggs can survive in both dry and cold conditions.
Risk Transmit pathogens and viruses, such as the yellow fever virus, dengue fever, Chikungunya fever and Usutu virus.

The tiger mosquito (Aedes albopictus) is a small black-and-white, daytime biting insect. It is native to the Far East but was accidentally introduced to Europe in the used tyre trade in the 1970s.

It has now spread through much of southern Europe and has been gradually pushing northwards.

Modelling has shown that southern England is suitable for this species. For several years, Public Health England has been running a network of mosquito detection points at UK ports and other locations.

These mosquitoes are largely urban and actively bite during the day. Where abundant, they can be a significant nuisance to people in their garden or sitting outside bars, cafes, parks etc.

More seriously, they can also carry human diseases. They have been responsible for outbreaks of Chikungunya disease in, for example, France and Italy in recent years, with several human deaths.

When might they arrive?

In September 2016, Public Health England found tiger mosquitoes for the first time in the UK at motorway services in Kent. Larvicide treatments were applied, and fortunately, the mosquitoes were eliminated.

Since then, there has been a trickle of similarly unsuccessful incursions.

However, the likelihood is that sooner or later, this mosquito will gain a toehold in the UK and then gradually spread, probably across urban or suburban areas, assisted by climate change.

Treatment: Are we prepared?

The short answer is no. You will almost certainly need additional training on key topics such as:

Identification
Tiger mosquitoes will need to be separated from the many other mosquito species that are present in the UK and which do not need to be controlled.

Understanding biology and habitats
Tiger mosquito larvae are usually found in small informal water bodies such as small drain sumps and water butts, not in larger ponds, lakes or marshes.

Mosquito surveying
Technicians will need to survey areas for mosquito breeding and separate mosquito larvae from other aquatic wildlife to decide which areas need treating.

Use of larvicides
The dosage and application of these (eg bacillus thuringiensis israelensis and silicone products) are very different from conventional residual sprays, so need to be fully understood.

Use of ULV insecticides
Again, ULV dosing and application is very different from conventional insecticide treatment. There is a lot of technology behind droplet sizes and mosquitoes and choosing the best time to treat.

Termites

Colouring Creamy white to dark brown/black, depending on species.
Size <25mm
Habitat Termites are detritivores, consuming dead plants at any level of decomposition.
Behaviour All termites are social insects and raise their young as a group. Each termite
colony is established and dominated by one queen and king.
Lifecycle Egg, nymph and adult stages. The queen produces thousands of eggs over her lifetime.
Risk Each year, termites cause an estimated £3.7billion in property damage.

Termites are social insects, usually living in large underground nests containing thousands of insects and feeding almost entirely on dead wood.

Several species occur in France and other European countries, with infestations spreading northwards in recent years.

Termites are now widespread in Paris, and infestations are even being found close to the Channel coast.

The main impact is the potential for severe damage to structural timber in buildings.

They are a greater problem than timber beetles because the individual beetles at least leave exit holes that can be easily spotted, and remedial treatments then applied.

Termites, by contrast, hollow out the timber from the inside, leaving an intact but thin layer of timber and paint on the surface.

It’s not until the door frame suddenly crumbles away in the customer’s hand that they realise they have a problem. UK buildings typically contain a lot of structural timber, so they are very vulnerable to attack.

When might they arrive?

In the UK termites are not native, but some were accidentally introduced from the Canary Islands to Devon in the 1990s, where they damaged timber in two houses.

Despite an extensive and very expensive eradication programme, it is still not clear whether they have been eliminated.

There is a continual risk of new introductions from southern Europe and beyond, with climate change making the UK ever more suitable for them.

Treatment: are we prepared?

Again, no! Termite control will be very different from any other form of UK pest control. Detailed training will be required on:

Termite surveys
An important part of termite control. Visual inspections, audio detection devices, and even detector dogs can be used. A detailed understanding of building construction is required.

Soil drenches
High volume insecticide treatments, typically injected around the footings of buildings. Powerful drills and large capacity pumps are typically required.

Termite baiting
A technique which has replaced some soil treatment. Perforated plastic cylinders are inserted into the ground around the building. They initially contain a non-toxic monitoring bait. If termites are detected, this is replaced with slow-acting toxic bait – termites take this back to the nest, where it eliminates the whole colony.

Case study

Termites in the Midlands?

We think they might have been brought in via timber that was imported about a year ago as that’s how long we think they’ve been active for.

Jason Cholerton, CSS Pest Services

BPCA member, CSS Pest Services, identified a small colony, initially thought to contain up to 30 termites, during a routine inspection in a reptile house.

After seeking confirmation, the termites were identified as Kalotermitidae, commonly known as ‘drywood termite’.

After notifying the non-native species secretariat, Jason Cholerton of CSS Pest Services said: “We think they might have been brought in via timber that was imported about a year ago as that’s how long we think they’ve been active for.”

The client later confirmed that the timber had been in tanks for 18 months and had been purchased from a UK timber merchant, who had also been notified.

With a plentiful supply of suitable wood, alongside consistent warm temperatures of between 24-26°C, the colony was able to develop.

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Source: PPC103