Culex sitiens

In March 2018, we found larvae from an exotic mosquito species, Culex sitiens, near the Kaipara Harbour, north of Auckland. Find out about the mosquito and what we're doing about it.



A closeup of a Culex sitiens mosquito on a human hand
Culex sitiens mosquito

Culex sitiens is wide-spread in Southeast Asia, the South Pacific and Australia.

It is known to transmit diseases such as Ross River virus. However, this is not a risk for New Zealand as this disease is not present here. Culex sitiens may also be able to transmit Japanese encephalitis but this has not been observed outside of a laboratory setting.

How was it found?

Culex sitiens larvae were found near the Kaipara Harbour in the Kawau Parau Inlet (north of Auckland). The larvae were found during regular surveillance as part of the Ministry for Primary Industries' (MPI's) National Saltmarsh Mosquito Surveillance Programme. So far, no adult mosquitoes have been found.

What's being done?

MPI was alerted to the suspected detection of the larvae on 9 March 2018. Further testing for identification was completed on 12 March.  

Contractors for MPI are now taking water samples and setting light traps to collect larvae and trap adult mosquitoes in and around the initial find. This will help us find out if there is a sustainable breeding population.

After returning to the initial find site on 16 March, 2 more larvae were found. The new find is not definite evidence that there is an established breeding population of the mosquito but does make it more likely.

We will have the necessary permissions in place to begin spot treatment when suspicious larvae are found as part of the sampling and trapping process. Our field staff will treat any suspicious larvae with a product called Vektobac, which is an inert bacteria granule. There are no human health concerns from using this treatment.

If there is a sustainable breeding population, it's likely that MPI will begin an eradication programme, after consultation with local iwi, residents and organisations. MPI has successfully eradicated exotic mosquitoes in the past.

We are also investigating how the mosquito may have entered the country.

Who to contact

If you see unusual mosquitoes call the Mosquito Hotline on 0800 MOZZIE (0800 66 99 43).

If you have health concerns after being bitten by a mosquito you can call the Ministry of Health's Healthline on 0800 61 11 16.

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