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Straits Times Forum Online 5 Oct 05 Restore nature's balance to fix Aedes mosquito problem Letter from YiJin Woo Selangor, Malaysia PlanetArk 19 Sep 05 Gulp! Indian State Fights Dengue with Fish Straits Times Forum Online 17 Sep 95 Frogs and toads can help to fight mosquitoes Letter from Seah Leong Khai Straits Times Forum Online 15 Sep 05 Try new method to curb dengue outbreak Letter from Dr E. Nugroho Batam Straits Times Forum Online 15 Sep 05 Enlist mosquito's natural enemies to fight dengue Letter from Loh Kwek Leong I SUSPECT the continuing high number of dengue cases is due to the fact that we have inadvertently removed the mosquito's natural enemies from the environment. Fogging kills a large number of mosquitoes but it also kills spiders, praying mantises and other insects that prey on adult mosquitoes. Also, as Singapore becomes increasingly urbanised, the natural habitats of dragonflies and damselflies disappear from the landscape. The nymphs of these two insects are ferocious predators and mosquito larvae make up a large part of their diet. When was the last time you saw a dragonfly? Where there is stagnant water, mosquitoes lay their eggs but dragonflies prefer such a condition too. A dragonfly nymph can remain in its larva stage for a long time. It eats a large number of mosquito larvae before it becomes an adult. Instead of fogging, wouldn't it be better to use a natural method to control mosquitoes from multiplying? Would it be feasible to breed large numbers of dragonflies and release them into the environment? Over the years, the authorities have been so diligent in spraying insecticide and fogging that they have created an imbalance in the ecosystem. It is time we take a fresh look at the problem from another angle. There is a need to restore the equation before dengue fever becomes an epidemic. Loh Kwek Leong Straits Times Forum Online 15 Sep 05 Try new method to curb dengue outbreak Letter from Dr E. Nugroho Batam I have an idea which to my knowledge has not been pursued elsewhere. In order to control the population of some insects, biologists have bred and released sterile insects to compete for sex with the general population. This results in declining insect population. This measure relies on competition for sex. Why not use a similar tactic to tackle the Aedes mosquitoes? Instead of getting rid of all breeding grounds, which to a certain extent has failed, we can provide breeding grounds for mosquitoes that we can control. In HDB flats, we can put water containers and check everyday to see if there are larvae in them. If so, the water is drained in a safe way to make sure that the larvae die. Use containers (black ones?) that can attract the mosquitoes. This way, we can provide a controlled breeding ground. This tactic will not get rid of all the mosquitoes but it will reduce its population. Of course, strict control is needed. I believe Singapore has that prerequisite. Dr E. Nugroho Batam Straits Times Forum Online 17 Sep 95 Frogs and toads can help to fight mosquitoes Letter from Seah Leong Khai Preventing the breeding of mosquitoes may be more effective than the search-and-destroy method in dealing with the dengue problem. I agree with Mr Loh Kwek Leong's suggestion (Enlist mosquito's natural enemies to fight dengue, ST Sept 15) to breed and use dragonflies to reduce the breeding of mosquitoes. There is another way to solve the mosquito problem. Why not use frogs and toads, which are the natural enemies of mosquitoes, to help us fight the battle? Frogs and toads eat mosquitoes and other small insects. In our kampong days, there were plenty of them in the rural areas, in the farms and even in backyards. Frogs and Aedes mosquitoes breed and live in clean water. It makes sense to release more frogs into the ponds and parks such as the Botanic Gardens and MacRitchie Reservoir. The frogs will feed on the larvae and adult mosquitoes and thus prevent the breeding of mosquitoes. Frogs love mosquitoes. Instead of eating frog's legs, we should get them from the frog farms and release them. Seah Leong Khai PlanetArk 19 Sep 05 Gulp! Indian State Fights Dengue with Fish KOLKATA - Indian health authorities are using colourful aquarium fish with a taste for mosquito larve to fight a dengue epidemic that has left dozens dead, health officials said on Friday. Dengue, which is transmitted by mosquitoes, has killed about 50 people and affected hundreds in the past few weeks in the eastern state of West Bengal where authorities are struggling to control the disease. Health officials have released thousands of gambusia and guppies -- small, brightly coloured freshwater fish popular in home aquariums -- in ponds, lakes, wells and stagnant water where mosquitoes breed. "Guppies eat mosquito larvae and help in checking the breeding rate of mosquitoes. These fish are being used successfully to fight dengue," said Prabhakar Chatterjee, West Bengal's medical services chief. Dengue is marked by high fever, headache, rash and nausea, and if not treated in time can lead to death. Health volunteers, medical students and voluntary organisations are distributing the fish. "Gambusia is a cheap and easily available fish that can eat daily its own weight in mosquito larvae or pupae," said Amiya Hati, an expert in mosquito-borne diseases. Authorities are encouraging the use of gambusia fish because mosquitoes have become resistant to many pesticides, such as DDT. The Straits Times Forum Online 5 Oct 05 Restore nature's balance to fix Aedes mosquito problem Letter from YiJin Woo Selangor, Malaysia The dengue outbreak has raised many interesting questions. The government has mainly blamed irresponsible households for not doing their part in cleaning up their compounds. A way to prove this would be to compare the number of 'mosquito breeding' fines to households in areas affected by the outbreak. If it is right, you should see a sharp rise in such fines. But I doubt this is the problem. People are no less responsible than they were 10 years ago. In fact, there has been rapid urbanisation over the past decades. Many kampongs that were prone to mosquito infestation had been replaced by modern housing projects. Swamps near the city had been filled in for development projects. Let me suggest another possibility why dengue cases have increased rapidly in our modern and clean cities. I think the cause lies in the decline of the mosquito's natural predators. When I was young, I remember the lizards on the walls of my house. There were insects such as dragon flies that preyed on smaller insects. At dusk, you could see small birds criss-crossing the skies feeding on insects. There were also more bats, toads and frogs. One bat can eat up to 3,000 insects a night. Today, we have killed most of these animals. I can hardly find a lizard in my house these days. The only thing stopping the mosquitoes are humans, and we are lousy mosquito killers. We have to think of the mosquito as part of a larger web in a complex urban ecosystem. We have to consider how different parts of this system contribute to the mosquito lifecycle and not just concentrate only on breeding grounds. If we can restore a balance in the population of the mosquito's natural predators, we will see a drop in dengue cases. YiJin Woo Selangor, Malaysia links Related articles on Singapore: dengue issues, policies, discussions |
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