The killer AT LARGE

CHENNAI: Aedes aegypti and Culex are prominent names in the vector control history of India dating back to the colonial era, but what has not changed is the scientific growth or temperament over the centuries. Whether British governance or Indian democracy, the mosquitoes are here to stay.

The WHO-dreaded winged insects, capable of spreading the virus infections, are not surviving but thriving. Vectors like mosquitoes, flies and rodents require three major factors to spread infection — the infected vector, humans and livestock, and a suitable climate.

Tamil Nadu with its warm temperature is a sanctuary for mosquitoes, admit industry experts. Thanks to the micro-level ambitious stormwater drain projects being implemented by the present regime, mosquitoes now have another fertile breeding ground, which according to entomologists is going unchecked.

Biologists and entomologists attribute the ecological imbalance that had taken away the predators of the mosquitoes adding fuel to the fire.

“In 1991, the Australian scientific community noted an increase in the new species of mosquitoes in the Island nation and subsequently took up vector control mapping and preventive measures. Today Australia is a well-prepared nation when it comes to handling malaria and lumpy skin disease in cattle,” opined retired veterinary professor and head Dr S Prathapan of Madras Veterinary College.

“Vector control is a serious subject and plays a major role in controlling vector-borne diseases and zoonotic infections. With the climate change impact visible, the need of the hour is a vector mapping programme that can forecast the impact of vector diseases. Another example is lumpy skin disease (LSD), a viral infection in cattle spread by mosquitoes and flies. Again, foreign countries like Australia are advancing in monitoring such diseases earlier, thereby taking preventive steps and further research,” Prathapan said.

In India, funds for research projects have been enhanced but there is a need for more funds and studies on vector control and zoonosis, explained the former director of veterinary clinics.

“To be precise, vermin (nuisance creatures) or species of less eco contribution like mosquitoes, cockroaches, rats, pigeons and pigs make more harm than good spreading the zoonotic infections,” said a former vice chancellor of Tamil Nadu Veterinary and Animal Sciences University. The biggest issue with both the Centre and the state is that vector control and zoonotic infections are treated at municipal and panchayat levels, leaving no funds for major research projects on insects, pests and virus-transmitted diseases.

The best practice is to cull birds during bird flu, kill pigs during swine fever and fumigate during a malaria outbreak. But beyond this, the former vice chancellor noted that there is no such scientific progress for the past thirty years in studying insects and their impact.

“The biggest issue is the ecological imbalance. Frogs and freshwater fishes like Gambusia affinis play a major role in arresting the larvae population of mosquitoes. This is like arresting the issue at the source. But the government machinery focus is on spending money on chemicals and insecticides,” said wildlife biologist and conservation scientist Dr A Kumaraguru.

“The moment when the predatory species are wiped out, the vermilion plays havoc on human life. Dragonflies, lizards and birds do play a major role in arresting the mosquito population. Gambusia can eat up to 150

larvae a day and dragonflies can clear thousands of mosquitoes within a few hours. Then there are paints and varnish that chase away lizards from our homes. A barn swallow can eat 60 insects mostly mosquitoes in a minute. Martins, bee-eaters and great tits can also consume hundreds of mosquitoes within a few hours. Birds like black drongo can arrest the migration of locusts like a bio shield. The issue is the loss of marine and bird life,” explained the seasoned bird watcher who is into DNA molecule study of disappearing vultures in the Sathyamangalam tiger reserve.

Further, with climate change becoming an issue, entomology and zoonotic science need an indepth study, he added.