Just when scientists were busy monitoring bird and butterfly migration within the state, new winged guests have begun to swarm the skies of Coimbatore — dragonflies. Scientists say the migration brings good information to the state this is scuffling with dengue as dragonflies happen to feed at the larvae of dengue-causing Aedes mosquitoes.
Of the 87 species of dragonflies recorded in Coimbatore thus far, best Pantala flavescens is found to be migratory in nature, says K Venkataraman, former director of Zoological Survey of India (ZSI). "Their migration is important as they feed on the Aedes mosquito larvae before the north-east monsoon sets in. Pantala flavescens, also known as wandering glider or globe skimmer can be seen swarming the skies of the city in the first week of October," he says.
The migration peaks in September and lasts till October with the species seen in large numbers in rivers akin to Noyyal, Bhavani and Aliyar and the hilly spaces like Siruvani, Nilgiris, Anaimalai and Palani. Around 90 species have been found in Western Ghats.
K A Subramanian, scientist and in-charge of southern regional centre, ZSI, says of the 488 species of dragonflies recorded within the nation thus far, only a handful are migratory in nature. "Wandering glider is the most common migrant. They breed in fresh water while on the move. They play a vital role in maintaining the balance of the ecosystem as they feed on insects and harmful pests in agricultural fields," he says.
Although scientists are yet to give an explanation for the reasons behind the sort of mass migration, Subramanian points to a popular principle which says that the migration is passive in nature and is guided by way of the winds of the northeast monsoon, which is why migrant dragonflies are found best across the inter-tropical convergence zone. According to the speculation, the migration route stretches from north India to Maldives to Africa. It takes almost three generations of dragonflies to succeed in Africa.
"Even though dragonflies breed only in fresh water, a scientist named Anderson found them in the Maldives which has no fresh water sources in November. He has inferred the dragonflies must have travelled from India (post October) and stopped at Maldives to rest during their journey to Africa," says M Suhirtha Muhil, a analysis pupil at Salim Ali Centre for Ornithology and Natural historical past (SACON)
Many, alternatively, rue that sufficient research have now not been made in India to corroborate these findings.
"In Europe, scientists have even tried to radio tag a particular species of dragonfly and study them. But there are not many studies on them in India," says Subramanian.
Muhil says all the way through her analysis on dragonflies she found that some species are found best in rivers, some in wetlands and some in woodland spaces. "Those in the forest area can never be found in wetlands. So, when a checkdam is constructed on a river and the flowing water becomes stagnant, some species leave the location and may become extinct in that region alone. So there are a lot of factors involved if we want to conserve them," she says.
Muhil says, it's difficult to test the behaviour of dragonflies in a lab as they feed on best certain species and do not live to tell the tale for lots of days.
Of the 87 species of dragonflies recorded in Coimbatore thus far, best Pantala flavescens is found to be migratory in nature, says K Venkataraman, former director of Zoological Survey of India (ZSI). "Their migration is important as they feed on the Aedes mosquito larvae before the north-east monsoon sets in. Pantala flavescens, also known as wandering glider or globe skimmer can be seen swarming the skies of the city in the first week of October," he says.
The migration peaks in September and lasts till October with the species seen in large numbers in rivers akin to Noyyal, Bhavani and Aliyar and the hilly spaces like Siruvani, Nilgiris, Anaimalai and Palani. Around 90 species have been found in Western Ghats.
K A Subramanian, scientist and in-charge of southern regional centre, ZSI, says of the 488 species of dragonflies recorded within the nation thus far, only a handful are migratory in nature. "Wandering glider is the most common migrant. They breed in fresh water while on the move. They play a vital role in maintaining the balance of the ecosystem as they feed on insects and harmful pests in agricultural fields," he says.
Although scientists are yet to give an explanation for the reasons behind the sort of mass migration, Subramanian points to a popular principle which says that the migration is passive in nature and is guided by way of the winds of the northeast monsoon, which is why migrant dragonflies are found best across the inter-tropical convergence zone. According to the speculation, the migration route stretches from north India to Maldives to Africa. It takes almost three generations of dragonflies to succeed in Africa.
"Even though dragonflies breed only in fresh water, a scientist named Anderson found them in the Maldives which has no fresh water sources in November. He has inferred the dragonflies must have travelled from India (post October) and stopped at Maldives to rest during their journey to Africa," says M Suhirtha Muhil, a analysis pupil at Salim Ali Centre for Ornithology and Natural historical past (SACON)
Many, alternatively, rue that sufficient research have now not been made in India to corroborate these findings.
"In Europe, scientists have even tried to radio tag a particular species of dragonfly and study them. But there are not many studies on them in India," says Subramanian.
Muhil says all the way through her analysis on dragonflies she found that some species are found best in rivers, some in wetlands and some in woodland spaces. "Those in the forest area can never be found in wetlands. So, when a checkdam is constructed on a river and the flowing water becomes stagnant, some species leave the location and may become extinct in that region alone. So there are a lot of factors involved if we want to conserve them," she says.
Muhil says, it's difficult to test the behaviour of dragonflies in a lab as they feed on best certain species and do not live to tell the tale for lots of days.
Migrant dragonflies bring along promises of rain, dengue-free state
![Migrant dragonflies bring along promises of rain, dengue-free state]()
Reviewed by Kailash
on
October 24, 2017
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