Search intensifies for foreign mozzie

By ROSALEEN MacBRAYNE

Surveillance has been stepped up in the Bay of Plenty for exotic mosquitoes that spread disease.

The Port of Tauranga, with estuaries and marshes nearby, is rated a high-risk entry point for the invaders.

Toi Te Ora Public Health has employed three students over the summer to set and monitor traps in sheltered sites between Bowentown, near Waihi Beach, and Cape Runaway.

Supervising health protection officer Eddie Ashcroft said Toi Te Ora was keeping an eye out for the southern saltmarsh mosquito in particular, an unwanted Australian visitor that carried the debilitating Ross River virus.

The mosquito was found around Kaipara Harbour in the Rodney district last February and was subjected to a full-scale spray eradication programme.

The pest, believed to have come in on ship containers, has also been discovered at Napier, Gisborne and Whitford in Manukau City.

Ross River virus can cause aching muscles and joints, fever, chills, headache and tiredness.

The Bay of Plenty's mild climate and suitable breeding habitats made it a likely area for exotic mosquitoes to establish themselves in, said Mr Ashcroft. Year-round surveillance was intensified in summer when the risk was higher.

"We don't have mosquito-borne diseases in New Zealand and the programme is part of our efforts at a national level to make sure we keep it that way," he said.

For three months, Tracey Lewis, Susan Goldsack and Ria Hayward are setting traps, observing potential breeding spots and gathering mosquito larvae for identification.

A combination of dry ice (frozen carbon dioxide), pheromone (which reportedly smells like "bad cow's breath") and light are used to attract the insects.

The special light draws them at short range to a fan, which whisks them on a one-way trip down a long sock into a specimen container.

No exotic mosquitoes have been found so far this summer.

In March 1999, two adult Asian Tiger mosquitoes and five larvae were found in old tyres on board an overseas container ship during a routine inspection at the Port of Tauranga. The breed is a potential carrier of dengue fever and Japanese encephalitis.

Ministry of Agriculture and Forestry staff began a spraying programme and set up 50 traps in a 500m quarantine zone, successfully controlling a spread of the pest.

Herald feature: Environment