In the context of climate change and global warming, all are concerned about conserving forests, planting and raising green islets at the cost of “degraded lands” with the deep-rooted assumption that forests sustain life the most. However, a study carried out by a team of researchers from the Central University of Kerala by taking dung beetles as models, suggests that it does not always hold true.
Dung beetles are pivotal to any terrestrial ecosystem for three major reasons - dung and carrion removal, nutrient recycling and mineralisation of soil, and secondary dispersal of seeds from the dung. They have rollers, dwellers, and tunnellers to disperse the ephemeral dung. Both the adults and grubs feed and develop on dung.
The team took the two habitats of sacred groves and adjoining home yards to investigate the habitat preference of beetles. Sacred groves are relics of secondary forests and yards are open orchards.
To understand the diel preference of the beetles, they sampled beetles using cow dung as a bait during day and night from 11 pairs of two habitats across Kasaragod district.
“I thought that forests, because they are cooler and shady, might support a greater activity of the beetles any time of the day,” said Asha, the Ph.D student of the ecology labs of CUK.
But, to their great surprise, dung baits placed in open yards attracted over 86% of the beetles collected in the study. Overall, beetles have a marginal preference for day as 60% of the them were collected during the day. The diel pattern of activity was contrasting for open and shaded habitats. In home yards, beetles preferred day over night for their foraging activities. In sacred groves, 70% of the beetles’ activity was during the night.
The two dominant species collected in the study, Tiniocellus spinipes and Tibiodrepanus setosus, were exclusively collected from home yards, and that too during the day. They were almost absent in the night in home yards and sacred groves. Nevertheless, the rollers restricted their activity to the sacred groves, but during the day.
Thermal tolerance of the beetles matters in their activities. The thermal tolerance of rollers might be lower than that of the tunnellers and dwellers, Sinu, who led the study, said.
“At a time when we downgrade grasslands and ecosystems other than forests as degraded habitats and use them for our developmental activities, we should be aware that those systems have their own ecology and sustain biodiversity that help terrestrial ecosystem to function well,” said Dr. Sinu.
It is said that if the dung beetles had not evolved on the Earth, the world would have been swamped by the dung of all animals, he said.
The paper, published in Scientific Reports, a journal from the Nature group, has K. Manoj and P.P. Megha as two other authors.
