More saltmarsh larvae detected

By ANNE BESTON

An aggressive, disease-carrying mosquito appears to have found its way to East Auckland after a second find of suspect larvae yesterday.

Scientists were working through the night last night to try to confirm the identity of the second find of larvae but Ministry of Health manager of public health programmes Graeme Gillespie said he was fairly confident the first larvae found were southern saltmarsh mosquito.

The first suspect larvae find was made on Monday at Turanga Creek in Whitford. The second find was made at the same site yesterday.

The Australian southern saltmarsh mosquito is a known carrier of Ross River virus, which has a range of health effects. Some people get aching joints and muscles, headaches, fever, chills and tiredness which can last for years. In about 10 per cent of cases, sufferers have developed severe depression and arthritis.

A ministry team flew by helicopter over a 25km stretch of the east Auckland coastline yesterday, checking routine sampling sites for more infestations of the mosquito after last weekend's king, or extra high, tide.

The ministry's chief technical officer for biosecurity, Dr Bob Boyd, said it was important to move quickly so any larvae which hatched during that tide could be found before they transformed into pupae.

The ministry is already fighting the Aussie mosquito on five different fronts. Using aerial spraying of Bti, a biological larvacide, it is spending $5 million to eradicate the insect in Gisborne, Napier, Mahia and Porangahau and is trying to bring it under control in the Kaipara Harbour area with a view to eventual eradication.

The Kaipara area is the biggest infestation of the aggressive mosquito with a potential habitat of more than 2000ha.

More than 170ha has been sprayed from the ground and the air at 22 sites.

Scientists say that with a flying range of about 5km it is unlikely adult mosquitoes have found their way to East Auckland from the Kaipara infestation but they cannot rule it out.

The mosquito could have hitched a ride on vehicles travelling from Kaipara.

Southern saltmarsh mosquitoes lay their eggs on vegetation just above the waterline but need water to hatch.

High tides, rain and wind that increases waves all encourage hatching.

They are an aggressive daytime biter most active at dawn, late afternoon and dusk.

Dr Boyd advised people in East Auckland to keep windows and doors closed, use insect repellent and coils and wear long clothing.

nzherald.co.nz/environment