KOLKATA: Forest officials regularly set trained elephants to control wayward elephants, or those out of their control. Kolkata Municipal Corporation officials are now desperately trying to set a mosquito against another, but they don’t know how to breed and “tame” them. In these days of dengue menace, nothing can be more frustrating.
KMC officials are sorely missing a particular variety, known as Toxorhynchities splendence mosquitoes – better known as friendly mosquitoes – that consume the larvae of aedes aegypti, the type that carries the dengue virus.
In a tantalising discovery, KMC officials found the friendly mosquitoes inside the Raj Bhavan, but regretted that there is no technology to breed these mosquitoes.
“If we could breed these friendly mosquitoes, the menace could have been controlled to a great extent,” said Debasish Biswas, the chief vector control officer of KMC.
Interestingly, this species doesn’t bite humans, or any other animal. In fact, this species don’t feed on blood.
The discovery of the species has triggered afresh waves of regret in the KMC headquarters on Wednesday.
“In early 2000 we decided on a breeding programme for these friendly mosquitoes in Kolkata. Unfortunately it is impossible to breed these mosquitoes in laboratory. Such a breeding programme was adopted in Hawaii but it too failed miserably,” said Biswas.
Though innocuous, these mosquitoes are bigger than the ones we see every day. They grow up to 40 mm in size (compared to about 28 mm to the ones seen regularly) and consume nectar and the larvae of other mosquitoes that are carriers of malaria and dengue.
The mosquitoes that are giving KMC sleepless nights are anopheles stephensi (causes malaria), aedes aegypti (causes dengue) and culex fatigans (causes filaria).
The friendly Toxorhynchites can eat up 40 to 45 larvae a day and have a lifespan of 20 to 25 days.
On Wednesday morning a team of the KMC health department, led by MMIC health Atin Ghosh, visited Raj Bhawan and found dengue larvae at the bamboo forest inside its compound. At the same time the team noticed the friend mosquitoes in its compound.
“We have found larvae of dengue at the bamboo grove located inside the Raj Bhawan compound. But we also found friendly mosquitoes inside the compound. Only if we could have found them in larger numbers,” lamented Atin Ghosh.
KMC officials earlier found these friendly ones in Jadavpur, Garia, Tollygunj, Behala, Southern Avenue and Tiljala.