Asian tiger mosquito in full attack

It is still too early for outright panic, but government organisations are on high alert. The Asian tiger mosquito is trying to invade the Netherlands, making use of old tires and lucky bamboo plants. These type of mosquitos were already successful in countries such as Italy, where the government intervened too late and the stinging creatures have set up a foothold. For the Netherlands, it is not yet too late, but will it be possible in the long run to stop the invasion?

 

The first Asian tiger mosquitos (Aedes albopictus), who originate from South East Asia, were first spotted in the Netherlands in 2005. Tires had been imported and the mosquito eggs had hatched after they came into contact with water. As soon as the mosquitos were spotted, they were efficiently destroyed. At the time, it seemed that the danger had passed. However, over the years, again and again the Asian tiger mosquito tried to conquer the Netherlands. Therefore, the NVWA (Netherlands Food and Product Authority; Nederlandse Voedsel- en Warenautoriteit) undertook action. It monitored on a structural basis all companies importing used tires on the presence of exotic mosquito species.

So far, three different types of exotic mosquitos have been found: the Asian tiger mosquito, the American rock pool mosquito and the yellow fever mosquito. Last month alone, the NVWA had to fight off the Asian tiger mosquito in not less than seven locations. Tire companies in Oss, Weert, Montfoort, Almere, Lelystad, Emmeloord and Hardenberg were responsible for the return of these insects. The destruction methods last several months and amongst others poison is used to kill both the larvae as well as the adult mosquitos. This radical method is necessary to prevent the mosquitos from getting a foothold.

The NVWA states that there is only a small change that the exotic mosquitos which are now in the Netherlands, carry dangerous viruses, but it can also not be excluded. Annette Lijdsman, Senior Communication Advisor, informs: ‘These mosquitos mostly come from car tire companies or businesses trading with lucky bamboo plants. The mosquito eggs don’t die when the products are gassed and they hatch when they get in touch with water. We have the feeling that the number of exotic mosquito cases is decreasing, but sometimes they make a comeback. When we spot this type of mosquito, we spray the entire company for two evenings with pesticide against adult mosquitos. We will not miss a single spot or corner. We also make sure that all larvae are killed and we will continue to do so until the end of the mosquito season.’

In the whole of the Netherlands, there are only three companies dealing with Lucky bamboo products. Very clear agreements have been set up with these companies and the NVWA checks intensely whether the understandings are being upheld. On June 25, the car tire companies set up a contract with the government. They promised that they would undertake action to prevent the exotic mosquitos from entering the country. The tires will only be stored under a roof, so that rainwater cannot reach the mosquito eggs. The NVWA will see to it that the companies uphold their promises.

Until now, the tax payers are the ones who have to cover all the expenses for fighting the exotic mosquitos. How bizarre is this? Should it not be the companies themselves, who are responsible for this mayhem, to pay for all costs? Lijdsman agrees, ‘It is not unthinkable that these companies will have to start contributing in the expenses, but this is a policy question. As the NVWA we exclusively deal with monitoring and combatting.’ She is convinced that it is not yet too late to withstand the exotic mosquitos. ‘In Italy the Asian tiger mosquito has become epidemic and it cannot be exterminated anymore. But over here in the Netherlands, where we occasionally find one mosquito at a time, it is still possible. But indeed, we are fighting nature.’

Indeed, the battle is still going on. Minister Schippers of the Ministry of Health, Wellbeing and Sport (VWS: Volksgezondheid, Welzijn en Sport) outlines the problems the NVWA is encountering in a letter she sent to the Tweede Kamer (House of Parliament). ‘There is limited scientific knowledge about effective preventive measures for preventing the establishment of invasive exotic mosquitos. For combatting these mosquitos we need biocides, which are currently not allowed in the Netherlands.’ However, the NVWA has received permission from the Dutch government to use these biocides after all.  

The lucky bamboo importers have a different problem; they will not get permission anymore to use larvicides. ‘Due to the lack of alternative effective means, lucky bamboo traders are not allowed to import these plants from third world countries’, says Schippers. Yet, she remains optimistic: ‘I expect that the permanent settlement of invasive exotic mosquitos can be prevented for the next dozens of years.’

(Gepubliceerd in The Holland Times, September edition)