TECHNICAL | PPC102 MARCH 2021

Professor Olivier Sparagano, Professor of Veterinary Parasitology at the City University of Hong Kong, shares with PPC how to correctly identify your arthropod pests to create an effective treatment strategy.

SPEED VIEW: 

• ‘Bird mite’ is a generic term that covers many species, which can be quite confusing
• Trapping arthropod pests can mislead by directing attention away from the culprit because of diverse arthropod populations present
• Eggs and larvae are usually not close to birds or humans; they could be in crevices far from treated zones
• Multiple treatment methods could prevent severe re-infestations and resistance to particular insecticides.

'Bird mite’ is a generic term often used by the general public, medical, veterinary and pest practitioners for a broad range of arthropod pest species.

However, it might confuse the situation for pest professionals on the ground, and it is essential to rationally and practically gather evidence:

• What arthropod pest species are present and problematic in human houses?
• What is the appropriate treatment to be used considering their behaviour, population dynamic and potential pesticide resistance?
• How do you verify your treatments worked?

Alongside the above questions, it’s crucial for pest controllers to handle their customers’ emotions, expectations and clearly explain the treatment limitations, to avoid a break in the trust relationship between the technician and their customer.

Which pest species is the problem?

Pest technicians will know very well that many arthropod pests can be found in a house simultaneously (bird mites, bed bugs, dust mites etc) including harmless arthropod species brought from outside through dirt and mud.

Interestingly, most samples I received from the general public were crop mites, which must have been brought under the shoes of the family or by their pets.

Trapping, vacuuming or aspirating arthropod pests can mislead you by directing your attention away from the culprit attacking your customers because of the diverse arthropod populations you might find.

Interestingly, most samples I received from the general public were crop mites, which must have been brought under the shoes of the family or by their pets.

Professor Olivier Sparagano

Pest controllers have to become criminal investigators and identify the real problem through clues left behind (marks on the skin, blood may be present on bedsheets, colonies found in cracks and so on).

You should always keep in mind that humans can be attacked by more than one arthropod pest simultaneously, and different treatments might be needed simultaneously. Also, remember that the most abundant species may be completely harmless – such as my often-gifted crop mites!

What is the appropriate treatment?

Suppose the bird mite, Dermanyssus gallinae (also known as the poultry red mite and not the only mite species you can potentially find on birds) is identified. In that case, it is essential to remember that only the adult and nymphal stages are blood feeders.

This can be feeding on blood from birds, your customers, some of their pets and even unwitting pest controllers not wearing the appropriate protective clothing!

Meanwhile, the mite eggs and the larval stage are usually not in close proximity with birds or humans and might hide in cracks and crevices far away from treated zones in houses.

Pest controllers need to remember that the first treatment would usually kill adults and nymphal stages, while eggs are well protected inside their shell. Therefore, it is paramount to treat a second time after the eggs hatch and reach the adult or nymphal stages where they’ll go looking around for blood.

If the second treatment is too soon, some eggs might not have hatched. But if new adult mites have already laid the next generation of eggs, you’re already too late.

What chemical or non-chemical treatments are available to you would depend on where you work (what is legally possible in your region or country).

Your solution should use an Integrated Pest Management (IPM) approach, which may combine several treatments. Multiple treatment methods could help to prevent severe re-infestations and resistance to particular insecticides.

How can you verify if your treatment worked?

Getting rid of 100% of the mites (which could be hiding anywhere) is a nice idea but unlikely to happen in reality.

However, reducing the mite population considerably to a level that stops bothering your customers is a far more achievable goal.

To check that you are going in the right direction, put traps down before and after your treatments (twice as mentioned before) and see if the traps catch fewer mites. You can also check with your customer to see if human attacks seem to have reduced after your treatments.

Often I have been asked when should we do the second treatment, and I can only give you a broad time window of between 5 and 15 days, depending on a few parameters:

• How long does the residual effect of the first treatment stay active in the house?
• What is the temperature and humidity in your customer’s house (bird mites like moisture)?
• How easy is it for them to find blood (number of family members, pets, visitors…)?
• How healthy are the mite population and their reproduction rate?

It is also essential that you advise your customers on preventing re-infestations and future attacks.

Delusional parasitosis

Customers with a pest problem, as you know, can be very distressed, emotional and occasionally have irrational ideas of what is happening.

In the past people have contacted me with supposed mite infestations, have often tried countless treatments, sought medical advice which they claim is wrong, and some used harsh and unnecessary treatments on themselves and their house before calling.

In the past people have contacted me with supposed mite infestations, have often tried countless treatments, sought medical advice which they claim is wrong, and some used harsh and unnecessary treatments on themselves and their house before calling.

Professor Olivier Sparagano

This could be delusional parasitosis, and a customer that has developed DP might never accept that your treatment has worked (even if there were indeed mites present to begin with).

Being called for an emergency at a family house, then going through a draining and emotional pest infestation crisis is never easy to deal with. Getting the correct pest identification is key, and managing expectations and treatment limitations at early stages will help you keep them on your side.

Discussing possible treatment failures and future prevention is also tricky but necessary to consolidate your relationship with your customers when dealing with such a problematic pest.

I wish you all the best in your pest control crusades and hope to see you at PestExtra on 16 March.

 Ask Olivier

Professor Olivier Sparagano will be at PestExtra giving a talk on bird mites and answering your questions. Meet all our expert speakers at the pest management show online.

pestex.org/register