Dengue biological control strategies promoted by WHO.
“In the absence of vaccines and effective drug against dengue, vector control has been considered as an important strategy to prevent and control the disease,” said Dr. Moh Seng Chang of the World Health Organization (WHO) during the Dengue Summit at the Heritage Hotel, Manila on 13 April 2012.
Among the strategies promoted by the WHO to control the population of dengue –carrying mosquitoes is the use of Dengue biological control agents such as larvivorous fishes and predatory copepods like water bugs. “There is no such complete strategy to control dengue mosquitoes, but the use of these biological agents could be a big help, as part of the integrated vector control strategies,” said Dr. Chang.
Two indigenous fish species were evaluated in India and found effective in controlling mosquitoes. Gumbusia affinis, a fresh water fish species, commonly known as “gambusia” or “mosquito fish,” can consume about 100-300 mosquito larvae per day while Poecilia reticulate, commonly known as “guppy fish,” can also consume about 80 to 100 mosquito larvae per day.
These fish species are surface feeders and are able to consume both anophelines (malaria mosquitoes) and cullines (dengue-carrying mosquitoes). They are resistant to water salinity, can easily multiply, withstand transportation and does not require specialized equipment or containers for survivals.
According to Dr. Chang, “These fish species are now being used in India to eliminate mosquito larvae in wells, domestic water containers, concrete irrigation ditches, industrial tanks and cisterns.”
Aside from larvivorous fishes, Dr. Chang also revealed that a water bug, Diplonychus indicus, can also be an effective biological control agent for dengue-carrying mosquitoes. In a study conducted by the Indian Council of Medical Research (ICMR), the introduction of water bug in mosquito habitats such as used tires, tree holes, and containers reduced mosquito populations of up to 98 percent.
“Larvivorous fishes and water bugs are environment friendly and are safe to use. It is also cheaper compared to chemicals used in controlling dengue-carrying mosquitoes,” said Dr. Chang.