Buddha once said that human has more to study from
butterflies than from text books. Same is the case with dragonflies, as far as
ecologists are concerned. But why? Wonder why do the elite human race with well-developed
brains at his command to survive natural challenges care such a weak creature?
Dragonfly resting on a leaf |
Best bio-indicators
Recent researches say that dragonflies, just like butterflies, are prominent indicators of ecosystem health. Any change in the ecosystem will first make a visible mark on dragonflies, be it the climate change or a chemical war.
For instance, some districts in the South Indian states of
Karnataka and Kerala report large scale health issues among the people due to
the areal spray of Endosulfan, a pesticide which is banned in many European
countries. The adverse effect of the pesticide was not studied before starting
its use. It grabbed media attention only when a doctor practicing in one of the
villages noticed large number of cancerous abnormalities among his patients,
years later.
But, the sign was visible very early, but nobody had the
eyes to see it.
The area recorded an abnormal fall in the population of
damsel flies and butterflies. They were the first creatures wiped out by the
pesticide reaction. If an ecologist or nature lover detected the change and
raised the alarm, they would have been able to avert many of the deaths (thousands
of them, which still continue) in the area.
Any such changes to the ecosystem first reflect on these
weak creatures. In South Africa, it was found that the species diversity of dragonflies
directly relates to human disturbance and resulting degradation of an
ecosystem. The dragonflies in the undisturbed areas were rare or endemic to
that region while those found at the disturbed riparian patches were common or
general in nature.
Biological Pest Control Agents
Damsel flies also offer important ecological services
Dragonfly larvae are known predators of larvae of mosquitoes and
black flies which are vectors of fatal diseases. The adult dragonflies devour mosquitoes and similar blood sucking flies which carry diseases.
It has made them effective bio control agents against mosquitoes and insect vectors of some diseases. Granite Ghost (Bradinopyga geminate), a container breeding dragonfly is widely
used in Thailand as a biological controller of Aedes mosquito which
spreads dengue fever. Its use in the urban areas was proved effective in preventing
dengue outbreak and spread.
Similarly,
dragonflies help the farmers in pest control too.
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