Dragonflies are bellwethers of earth’s ecosystems, Pg13

Key Highlights:

• Dragonflies, belonging to the order Odonata, serve as crucial bellwethers for the health of Earth's ecosystems.
• India is home to approximately 600 species of Odonata, with new discoveries often made in the Northeastern States and Western Ghats.
• Dragonfly populations are declining globally due to excessive pesticide use, particularly systemic pesticides, and adverse climate change impacts like droughts and floods.
• These insects are vital predators, with aquatic nymphs consuming mosquito larvae and adults preying on agricultural pests.
• Their unique visual system involves 16 or more genes for visual opsins, allowing them to perceive ultraviolet light.

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Detailed Insights:

• Dragonflies have an ancient lineage, with ancestors dating back 300 million years, possessing similar aerodynamic features but much larger wingspans.
• Their life cycle is split, with larvae (nymphs) living in water and adults being terrestrial and aerial.
• Nymphs are highly effective biological control agents, capable of consuming hundreds of mosquito larvae daily.
• The presence of healthy dragonfly populations in agricultural areas indicates sustainable farming practices with minimal pesticide use.
• Climate change impacts, such as altered rainfall patterns, severely affect endemic species like the blue hawklet in the Western Ghats.
• Research into dragonfly eyes reveals a highly sensitive visual system far more complex than that of humans.

Key Concepts Involved:

• Odonata: An order of predatory flying insects that includes dragonflies and damselflies, characterized by large eyes and two pairs of strong, transparent wings.
• Nymphs: The immature, aquatic larval stage of insects like dragonflies, which undergo gradual metamorphosis without a pupal stage.
• Systemic pesticides: Chemical compounds absorbed by plants and distributed throughout their tissues, making the entire plant toxic to feeding insects.
• Bellwether species: Organisms whose health or presence indicates the overall condition or health of a particular ecosystem or environment.