Jungle Warrior to Fight Aedes

Thursday, 31 January 2008

Jungle Warrior to Fight Aedes

Fighting fire with fire...this mosquito is twice the size of the Aedes species.

Carnivorous babies...the Toxorhynchites splendens larvae seen here eating other mosquito larvae

Mosquito man...Prof. Dr. Abu Hassan Ahmad with his specimens of mosquitoes in his lab in USM

Pilot project to introduce jungle mosquitos in Subang Jaya to start soon

SUBANG JAYA: Fed up with the neverending battle against dengue in the municipality, the Subang Jaya Municipal Council (MPSJ) is going back to nature to fight fire with fire.

A partnership is being established with Universiti Sains Malaysia (USM) in Penang to introduce a biological enemy of the Aedes mosquito, particularly the Aedes aegypti, to help reduce the threat of dengue, according to MPSJ Health Director Dr. Abdul Rahim Ahmad.

The larvae of one jungle variety, the Toxorhynchites splendens, consume larvae of other mosquito species, particularly the Aedes larvae.

These cannibalistic mosquitoes are bigger in size but they do not attack people because they are not blood-suckers, according to Prof. Dr. Abu Hassan Ahmad of USM School of Biological Sciences.

The adult mosquito is easily recognised by the proboscis that is curved backwards in both sexes and is incapable of piercing the skin.

Their larvae often dark reddish in colour are large and like those of the Culicinae, have siphons. They are predacious on larvae of other mosquitoes and on their own kind. They have occasionally been introduced to areas in the hope that their voracious larvae will help reduce the number of pest mosquitoes, according to a research carried out by the Forest Research Institute of Malaysia (FRIM) Entomology unit.

Larvae are found in container-habitats, such as tree-holes and bamboo stumps, tin cans and water-storage spots.

The adults are not blood-suckers but subsist on nectar and other natural carbohydrates.

By introducing them to the urban environment, it is hoped that they will help check the breeding of Aedes, according to Dr. Abdul Rahim.

Such measures may be needed in the war against the Aedes mosquito as it is evolving into a super-resistant breed, according to USM's Prof. Dr. Abu Hassan, who has researched insects for more than 25 years.

“It is very important to reduce mosquito breeding sites, as fogging only kills the adult mosquitoes.”

“Draining water containers without cleaning them is not enough as the eggs can stick to the sides of the containers even when the water is drained and survive for up to six months without water. On coming into contact with water, the eggs will hatch and the larvae will find their way into waterlogged areas,” he added.

Prof. Dr. Abu Hassan, who had himself suffered from dengue haemorrhagic fever in 1997, said that infants and children should be made to sleep under mosquito nettings. Mosquito repellents must be switched on from 6 pm onwards. Mosquito sprays must be used often in dark areas of the house day and night, under the beds and sofas and in between curtains and decorative plants, he added.

In laboratory conditions, their life cycle is as follow:

Egg hatching – 2 days

Larvae – 10 -14 days

Pupae emerging – 3-4days

Adult life span – 3 weeks

Toxorhynchites contains about 76 species which are mainly tropical, although a few species occur in North America, eastern Russia and Japan. In a scientific paper on the Toxorhynchites, USM Associate Professor Dr. Yap Han Heng wrote, “We believe we have a vegetarian which does no harm to any human being and is at the same time a deadly foe to the young of other kinds of the genus (mosquitoes).”

Both MPSJ and USM are expected to introduce small numbers of the mosquitos and also the eggs to dengue prone areas.