Super resistant aedes evolving

Star: Bad news. The aedes mosquito, the source of the dengue fever across the country, has evolved into a super resistant menace.
Even its eggs can survive for a long period in very harsh and tough conditions without water.
Findings by Universiti Sains Malaysia (USM) entomologist Prof Abu Hassan Ahmad showed the eggs of the aedes mosquito can withstand extremely dry conditions.
And they are able to survive in these conditions for up to six months.
However, said Prof Abu Hassan, the eggs would need to be laid in water first.
“Our lab tests have shown that the eggs can survive for four months and we are sure they can even last up to six months without a drop of water.
“We have had a very long dry spell and in the last month we’ve had rain.
“With the onset of rain, the eggs will hatch and the larvae will find their way into waterlogged areas,” he told The Star.
Prof Abu Hassan spent more than 20 years studying mosquitoes, and nearly lost his life to dengue eight years ago.
He said fogging would only kill the adult mosquitoes but would not affect the eggs that had been laid.
“The eggs are laid in tree crevices, drains and containers when water collects there.
“It is impossible to destroy the eggs totally.
“Our efforts should be to drastically reduce the number of adult mosquitoes,” he added.

In Sarawak, studies by the Miri City Council’s health and environment department found these astonishing and unexpected characteristics of the aedes mosquito:
# THE eggs have a very strong shell that cannot dry or crack for as long as they are incubating in mud, soil, damp leaves or wet sand;
# THE eggs can survive for a long period under such conditions and will hatch when the next round of rain comes, forming a small pool of water to enable the larvae to swim out;
# CONTINUOUS fogging with the same chemical will, in a short time, result in a change in the immune system of the aedes mosquito, enabling the insect to adapt to the chemical and shield itself from poisonous effects;
# THE mosquitoes can breed in all types of water, even in clean water in bath tanks or any storage tank.
“These studies have helped us formulate new fogging components to kill the adult mosquitoes,” said city Mayor Datuk Wee Han Wen.
“We have to keep changing the mixture of chemicals by using different varieties at regular intervals.
“We are also conducting ‘search and destroy’ missions in all open spaces, even where there is no stagnant or clean water,” he said.
So far this year, Miri has recorded 60 confirmed cases of dengue, but there has been no death.
Health Minister Datuk Dr Chua Soi Lek had said that the Government had started to use larvicidal biological control Bti (bacillus thuringiensis israeliensis) in the fogging of dengue-prone areas since August.