HYDERABAD: Call it winter’s blessing. The good news is that the number of aedes mosquitoes which cause dengue and chikungunya has come down in Hyderabad during winter. But the bad news is that the number of culex or “nuisance-causing” mosquitoes has remained constant since monsoon, informed chief entomologist of Greater Hyderabad Municipal Corporation (GHMC) Dr Ram Babu.
“Aedes mosquitoes can fly up to a range of 100 and 400 metre whereas culex can fly up to four km. Also, aedes mosquitoes breed in small freshwater spots like discarded tyres and water pots during the monsoon, which must have dried up. And since they cannot fly for long distances they eventually die. However, some of them hibernate during winter,” he explained.
Temperature plays a vital role in the lifespan of mosquitoes. During winter, the population of mosquitoes declines. If the temperatures are below 16 degrees Celcius, breeding activity comes down. “But it is not the same in Hyderabad. The water bodies and lakes in the city are full of sewerage and chemicals. The influence of harmful chemicals keep water bodies warm, and so, the culex mosquito species which can fly for longer distances in search of breeding sites continues to survive,” said the entomologist.
Recently, GHMC’s entomology wing conducted a mosquito survey at Rashtrapati Nilayam, Raj Bhavan and a few other areas in the city. The most common culex mosquitoes are still prevalent, he said referring to the survey report. “But the presence of vector-spreading aedes mosquitoes has significantly declined,” he added.
Aedes mosquitoes which are hibernating right now will emerge when temperatures rise. They start rising during summer, and become prevalent during monsoon. Culex mosquitoes, however, remain year-round, thankfully they do not cause any severe diseases. Yet, they are still a problem, the entomologist said.