About 4,500 guppy fishes to be introduced into wells, sumps in houses at Poondhottam It is a method of biological control of mosquitoes It neither affects environment nor harms non-target organisms VELLORE: About 4,500 guppy fishes were distributed in sachets free of cost to 321 residents of Poondhottam area here on Friday, as part of a malaria prevention campaign launched by the Zonal Entomological Team (ZET) of the Department of Public Health and Preventive Medicine. V. Rajagopal, senior entomologist, ZET, said that fishes reared at ZET were introduced into the wells and sumps in the above houses during the campaign. Introduction of guppy fishes (scientifically known as Poecilia) is a method of biological control of mosquitoes, which is an integral part of the strategy adopted for the control and prevention of disease-causing insects, including mosquitoes. These methods of insect control are based on introduction of various pathogens and predators of disease-causing insects. Such agents range from viruses, bacteria, protozoa, fungi, nematodes and natural predators such as larvivorous fishes. However, the effective use of biological methods of control requires a good knowledge of bionomics of disease-causing insects in relation to ecological conditions. Dr. Rajagopal said that of all biological control methods, the use of larvivorous fishes has been the most successful in countries such as Spain, Italy, Greece, Malaysia, Madagascar and several parts of South East Asia, including India. The special merit of these small fishes lies in their innate capabilities to survive and multiply in non-permanent waterbodies where other species would perish. Biological control of mosquitoes with fishes is directed towards the elimination of aquatic stages of mosquitoes as the larvae and pupae are readily devoured by these fishes. Larvivorous fishes lend themselves better than any other biological agents for immediate use in developing countries. The use of fishes for biological control has definite advantage in that they neither contaminate the environment nor harm the non-target organisms, especially predators in the ecosystem. The senior entomologist said that even though malaria has been successfully eliminated from Vellore after 1995, thanks to the successful biological measures with community participation adopted by ZET, the threat of resurgence is possible as malaria-transmitting mosquitoes are still prevalent. Vulnerability to malaria in Vellore has greatly increased due to medical, educational tourism and other tourist interests that have come up recently in Vellore.