THE CURSE OF THE TIGER MOSQUITO

The tiger mosquito – a potential carrier of dengue fever, Zika, and chikungunya – has already doubled in number and will be present in all areas of Spain this summer – according to preventative pest control company, Anticimex. This rise can be attributed to the heat and the amount of rain in some parts of Spain over the past few months. Dr. Mikel Bengoa, a Doctor in Entomology who specialises in the tiger mosquito and works with Anticimex, states that “This insect will be a bigger problem on the Mediterranean Coast, but this year it will reach areas that it wouldn’t have in ‘normal’ years.”

WORDS MARISA CUTILLAS

Dr. Mikel Bengoa

© Courtesy of Anticimex

The active season for this insect lasts from May to October and it tends to peak in September. The situation “will be worsening over the next few weeks,” says Bengoa, adding, “The recent closure of borders will reduce the likelihood of transmission but we should remain vigilant and take preventive measures.”

Not all tiger mosquitoes carry dengue fever, Zika, and chikungunya but they are vectors for the disease – meaning that if they bite someone with the virus, they can then pass it on. These three diseases are very serious; chikungunya can cause disfiguration of the body for various months, dengue often requires hospitalisation and can be lethal, while Zika can cause severe birth defects.

Dr. Bengoa, who has been fascinated by insects since he was a child, answers a few of our burning questions. My take on our interview is that, if you have a villa, you should definitely be taking steps to reduce or eliminate tiger mosquito populations in your garden and in surrounding areas.

WHICH SPECIES IS THE TIGER MOSQUITO?

“‘Tiger mosquito’ is the common name for Aedes albopictus, an exotic mosquito in Spain. It is reared in small amounts of water outdoors and is located close to human beings because we provide it with the water recipients and blood it needs to thrive. It is considered the secondary vector for various arboviral diseases like dengue, chikungunya or Zika, but it is not as effective as another species called Aedes aegypti, which is not currently present in Spain.”

THE TIGER MOSQUITO IS CURRENTLY A BIG PROBLEM IN SOUTHEASTERN ASIAN AND CARIBBEAN COUNTRIES BECAUSE OF DENGUE, ZIKA, AND OTHER DISEASES. HAVE THESE DISEASES EVER BEEN A THREAT IN SPAIN?

“In 2018, six cases of autochthonous dengue fever linked to the tiger mosquito were diagnosed in Spain, but the risk of an outbreak is not very high. The main threat they pose at this point in time is pain and discomfort, as their bites can cause severe reactions. The tiger mosquito is now a big problem in New York and New Jersey and it is making its way across the globe. Entomologists and pest control companies have to monitor its populations in order to prevent an increase in numbers and to reduce the possibility of arbovirus disease outbreaks. In 2017, the Aedes aegypti mosquito was discovered in Fuerteventura and thanks to quick action, the species was eradicated.”

WE HAVE HEARD OF DENGUE FEVER AND ZIKA IN THE MEDIA BUT CHIKUNGUNYA IS A LESSER-KNOWN DISEASE. WHAT IS IT?

“Chikungunya derives its name from kungunyala, the Swahili word for the characteristic stooped posture of patients with the disease due to their musculoskeletal symptoms. Its symptoms are high fever and pain in the articulations and in severe cases, it causes the body to bend forward. This effect lasts for around six months.”

HOW DID THE TIGER MOSQUITO ARRIVE IN SPAIN?

“We are unsure but we think it spread to the U.S. and Europe through the importation of old tyres for use in recycling. Rubber is recycled into so many things – including roads – and this material is constantly being shipped to the U.S. and other countries. Mosquitoes love laying their eggs in tyres, which can retain small amounts of water. They do so in other water containers as well – including pots with standing water, toys with rainwater, even a bottle cap.”

WHEN WAS THIS INSECT FIRST FOUND IN SPAIN?

“In Spain the first discovery of the tiger mosquito was made by doctors in Sant Cugat del Vallés in 2004, who found that they were treating many patients

with odd-looking bites. They concluded that these bites were caused by an invasive species, but they didn’t know which one. Doctors asked help from an entomologist at the Mosquito Control Service of Baix Llobregat and the latter discovered that the guilty party was none other than the tiger mosquito.

Tiger mosquitoes probably first entered Spain via Italy since we know they have been present there since 1997 (they were first found in the U.S., meanwhile, in 1979). Since car travel between European countries is so prevalent, they probably spread in this manner. One study by researchers in Barcelona showed that there are around 70,000 cars with a tiger mosquito in the metropolitan area of Barcelona every day. It is very easy for mosquito populations to spread as they are so aggressive that they can follow us into cars when we enter them. Later, when we arrive at our destination, the female mosquito flies out, and if she finds a water deposit, she lays her eggs in it.”

WHAT KNOWLEDGE DO WE HAVE OF THE TIGER MOSQUITO THAT CAN HELP US ‘BEAT’ IT?

“We know that it is lowflying; this is why it tends to bite the ankles and calves, not the arms or face. We also know that this mosquito flies a small distance in its lifetime (around 400m) and that it doesn’t migrate very far from where it is born. It tends to remain within a 50-metre radius.”

WHY ARE THESE MOSQUITOES SUCH EFFECTIVE VECTORS?

“It is the viruses that overtake them which are effective. The mosquito ingests the virus when it bites an infected person. This virus then has to make its way through the digestive system and travels all the way to the salivary glands of the mosquito, where it replicates in astonishing numbers. This in turn makes the mosquitoes thirsty so they bite more people. When a person is infected, their temperature rises and they in turn become more ‘attractive’ to mosquitoes. It is a highly complex cycle and a perfect one for the virus to reproduce.”

WHAT TYPE OF HOMES DO THEY ACCUMULATE IN?

“They tend to proliferate in homes with gardens – for instance, villas, since there are often toys, pots, and other items that can collect standing water there.”

HOW CAN YOU HELP PEOPLE WHO THINK THEY MAY HAVE TIGER MOSQUITOES IN THEIR VICINITY? IS FUMIGATION ALWAYS REQUIRED?

“By conducting a very detailed inspection. Surprisingly, fumigation is a last-case resort at Anticimex and we try to solve the problem without chemicals if possible to lower the undesired effects on the surrounding beneficial fauna. Sometimes the entire problem can be solved with something as simple as removing a couple of pots, tyres, or anywhere where we find the mosquito or its larvae. We have even had to get rid of small outdoor fountains because they can be breeding grounds for mosquitoes. We also place specialised traps in strategic areas.”

HOW ELSE CAN PEOPLE PROTECT THEMSELVES AGAINST TIGER MOSQUITOES?

“If they are travelling to an area known to have tiger mosquitoes they should wear long sleeves and apply a repellent solution containing DEET or Icaridin. It is important to be very thorough and to apply the repellent to all exposed areas, including the ankles. If you miss a spot, they head straight for it. Don’t bother with citronella bracelets, because they don’t work.”

FINALLY, CAN YOU TELL ME WHY YOU DECIDED TO BECOME AN ENTOMOLOGIST?

“I grew up in my parents’ villa and I used to love walking in the land surrounding it, collecting insects. When I heard about the tiger mosquito, I grew fascinated by how it transmitted disease and I decided to devote my doctoral thesis to it.”

Anticimex Marbella. Pol. Ind. Nueva Campana, Nave 95, Marbella. Tel: 951 120 201. www.anticimex.com