Often in the headlines due to threats to its existence, the Hesaraghatta grasslands, located in the catchment area of Hesaraghatta lake in northwest Bengaluru, are well-known among ecologists for their rich biodiversity. These grasslands support a diverse array of species and provide essential ecosystem services, particularly as an important grazing ground for the livestock of local communities.
Entomologists from the Ashoka Trust for Research in Ecology and the Environment (ATREE) have now discovered a new species of dung beetle, Onitis visthara, further emphasising the urgent need for the conservation of the grassland ecosystem.
Importance of dung beetles
According to a release from ATREE, an average cow produces approximately 30 kg of dung daily, amounting to over 10 tons per year. With India having the world’s largest livestock population, exceeding 535 million heads, the amount of excrement produced is substantial and plays a crucial role in nutrient cycling.
Grasslands at Hesarghatta. | Photo Credit: K. BHAGYA PRAKASH
“A significant portion of this dung is processed and decomposed by dung beetles, which belong to the family Scarabaeidae. These beetles feed, breed, and nest in the dung, either burying it or breeding directly within the dung pats,” said the release. This finding is part of a broader effort to revise the taxonomy of the genus Onitis in the Indian subcontinent, during which two other new species were also discovered: Onitis kethai from Biligiri Rangaswamy Temple Tiger Reserve, Karnataka, and Onitis bhomorensis from Tezpur, Assam.
“Cattle dung is a major source of greenhouse gas emissions, contributing significantly to climate change. However, by burying the dung, dung beetles help reduce these emissions. Additionally, these beetles enhance nutrient cycling, improve soil aeration, aid in secondary seed dispersal, and help control parasites,” said Seena Karimbumkara, researcher and lead author. Along with researcher Priyadarsanan Dharma Rajan, she has been studying dung beetles for over 20 years and conducted an extensive study to complete a monographic revision of the Onitis genus of the Indian Subcontinent.
A rare genus
Onitis is a relatively rare genus of dung beetles found in the Afrotropical, Oriental, and Palaearctic regions. Before the discovery of the three new species, only 176 species of Onitis had been reported globally. All species of this genus are tunnellers, meaning they bury large quantities of cattle dung beneath the dung pat to provide food for their larvae.
“Onitis visthara is broader compared to other Onitis species. So it is named visthara, which means breadth in Kannada, while O. kethai is named after our field assistant, the late Ketha Gouda, and Onitis bhomorensis is named after the bridge “Kolia Bhomora” across Brahmaputra, from where the new species was collected,” added the release.
Pressure on green spaces
Priyadarsanan Dharma Rajan, who leads the insect lab at ATREE, said, “Rapid urbanisation, along with growing industrial and commercial activities, has placed tremendous pressure on urban green spaces. Bengaluru’s natural landscape was once dominated by dry deciduous trees, interspersed with wetlands and open grasslands. The Hesaraghatta grasslands and the nearby Avalahalli forests are among the few remaining patches of this original vegetation. Given their rich biodiversity and the valuable ecosystem services they provide, these landscapes should be protected as a biodiversity heritage of Bengaluru.”
Published - September 14, 2024 07:44 pm IST
