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|
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
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.