- A new study shows a decline in dragonfly and damselfly species diversity in and around Pune city.
- Rapid land-use change in the region and water pollution are found to be some of the reasons for this decline.
- A previous study from the region has shown damselflies to be more sensitive to local water quality than dragonflies.
One doesn’t normally associate terms such as “armageddon” or “apocalypse” with tiny creatures like insects. Yet, in the scientific world, this association has been drawn, for alarming reasons.
Concerned about the rapid decline of insect populations worldwide, triggered by a 2017 German study that showed a 76% decline in insect numbers in the country over 27 years, some scientists around the world say that the Earth has either entered or is in the midst of the sixth mass extinction, also called the Holocene or the Anthropocene Extinction. They call it the “ecological apocalypse”, driven primarily by human activities resulting in the mass extinction of insect populations, referred to as the Insect Armageddon.
While experts differ on this theory, some even calling it alarmist, a group of scientists in the Western Ghats named a new-to-science damselfly, Armageddon reedtail (Protosticta armageddonia), in 2023. “We wanted to highlight the climate impact on insects, especially the Odonata species,” explains evolutionary ecologist Pankaj Koparde, who is an assistant professor at the MIT World Peace University (MIT-WPU) in Pune, Maharashtra.
Koparde and his team have been investigating changes in Odonata species (dragonflies and damselflies) in Pune district, along with other related studies such as land-use change and the status of the city’s rivers since 2011. Fourteen years of regular monitoring of the species make their study perhaps the only long-term monitoring project of Odonates in India so far.
On a wing and a prayer
Aligning with the global trend of insect decline, the latest published study from the team points to the absence of eight Odonate species in Pune that were recorded before 2010. At the same time, Koparde has some good news that could offset this, “While we couldn’t find eight species that were recorded previously, we discovered 27 new species,” he shares, referring to data from pre and post-2010 reports, adding that this could mean, “we still don’t have complete records of all Odonates.”
He explains that they relied on multiple datasets to make the study robust. “The data from our extensive field surveys since 2019 served as the primary data, while many published works, including books and previous research papers, formed the secondary data. The contribution of citizen science provided the additional third layer of data,” he elaborates. “We also had information available from the British, starting from the mid-19th century, recorded in the book The Fauna of British India. These are very old taxonomic monographs in which there is data on many places, including some parts of Pune.”
One of the most ancient species to have perfected flying, dragonflies have fossil records dating as far back as 213 million years ago. The most interesting aspect of dragonfly evolution, however, is that they haven’t changed much morphologically over this period, except for their size, according to senior scientist at the Zoological Survey of India, K.A. Subramanian, who is not associated with the Pune study. As astonishing as it may sound, records reveal that dragonflies were the size of pigeons back then.
Over 6,000 species of Odonates (dragonflies and damselflies) are described worldwide. “There are about 525 species recorded from India, most of them restricted to the Western Ghats and Eastern Himalayas,” Subramanian informs Mongabay India. They are the biggest wetland predators, capable of annihilating many fellow insects and other invertebrates during both their adult and larval stages. For these reasons, they are considered a good indicator species of wetland health. Subramanian says that Pune has a history of Odonate studies since the British which continues even now.
Sensitivity to habitat changes
Koparde highlights the year 2010 as a landmark year for Indian Odonatology. A book, Dragonflies and Damselflies of Peninsular India, written by Subramanian and edited by renowned ecologist Madhav Gadgil, provided all the information a dragonfly enthusiast needed to understand the insect. “Many people, including me, took a keen interest in the species after we read the book,” Koparde says, highlighting that even non-academic people felt empowered to take up Odonata studies. “So, prior to the book, Odonata identification was not accessible to laypeople. When the book was made available to the public, a lot of people — most of them into birdwatching — found a new hobby, a new niche to explore,” he adds.
Additionally, social media groups and forums were established, including a Facebook group called “Dragonfly India”, which was later renamed “Dragonfly South Asia” as it grew and transcended geographical boundaries. It now has over 9,000 members, Koparde elaborates. In their studies, Koparde and his team use pre- and post-2010 as an important categorisation. “Citizen science involvement after 2010 gave the study of dragonflies an edge that was absent before that year,” he says.
Both the larvae and adults of Odonata are highly sensitive to their residual habitat characteristics. Thus, the presence or absence of certain species of Odonates in a given area indicates the nature of that habitat as well as its quality, explains the paper. Rampant land-use change has significantly affected the species, Koparde says. “They need cleaner waters, which is not the case now,” he adds, referring to a subsequent study the team conducted on land-use change in Pune, which is yet to be published. Koparde also says that better data collection could have made understanding the species’ decline easier.
In a separate study, published in 2020, in which Koparde was also involved, the team examined the water quality parameters and how they correlate with species richness in specific sites. The year-long study found that high species diversity was associated with sites where local disturbances were at moderate levels, suggesting that reducing anthropogenic pressure on water bodies in highly populated areas could help maintain species diversity. The study at six sites along the Mula river in Pune also reiterated an earlier finding — damselflies are more sensitive to habitat change than dragonflies and, hence, more affected by local waterbody conditions.
So, at least for the sake of these lovely damsels in distress, we must keep our green spaces and water bodies pollution-free.
Read more: High-flying dragons: how the globe skimmer migrates across the Indian Ocean
Banner image: A river heliodor damselfly. Image by Ameya Deshpande.
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