At Empress Garden in Pune, survey conducted to assess insects’ diversity, microhabitats

Admitting that insects are largely misunderstood creatures and perceived as something to be scared of or eliminated, Paranjpe says that little light has been shed on the fascinating aspects of insect life. The garden has conducted a daytime survey “to assess the diversity and microhabitats of insect species”, within its 39 acre premises. The survey is a result of another assessment that found almost 40-45 species of insect-eating birds at Empress Garden. “We were convinced that there would be enough diversity of insects for them to feed on. We decided to conduct a proper study,” says Paranjpe. Significantly, the survey comes at a time when rapid urbanisation and depleting green cover in urban spaces have impacted insect populations.

The survey, which began on October 1, 2023 and continued till September 20, 2024, involved studying habitats, from bushes, trees, grass patches and hedge plants to garden and wooded regions. Among the other spaces that the team of six searched was a small stream that supports insect life, such as dragonflies and damselflies. Sampling was split into three seasons – October to January, which are the winter months; the summertime of February to May; and the monsoon season of June to September.

The researchers have documented 10 insect orders. The Lepidoptera or butterflies and moths, were the most abundant, at 30 per cent of the total insects recorded. Hemiptera or true bugs came next, at 26 per cent while Odonata (dragonflies and damselflies) were at 19 per cent. “Other orders recorded include the Coleoptera (bettles), Orthoptera (grasshoppers), Mantoidae (Praying mantis), Neuroptera (antlions, lacewings) and Blattoidea (cockroaches),” says the report.

“There are some surprising findings. The tortoise beetle, for instance, was found, not on its host plant, but in a completely different medicinal creeper. We don’t have any reports of this beetle completing its life cycle on this type of plant earlier,” she says. Another finding was the great swarm of Picture Wings. “Though not rare, these insects were not seen in such large numbers previously,” says Paranjpe. Then, there are insects that are difficult to even identify at the level of species.

The researchers have not only made written documentation of the findings but taken photos and videos to record insect behaviour. The RRBCEA Insect Survey Report is also being turned into a booklet that will be available to anybody who wants a better understanding of insects in the garden.

The booklet is likely to be available from Wednesday, March 26. “A common hedge plant in Pune, seen on road dividers, is the oleander. The bitter leaves, which contain toxin, cannot be eaten by cattle but, little known to people who pass the trees every day, it is the host of the Oleander hawk-moth which lays eggs on the leaves. The caterpillars eat the leaves and accumulate the toxin into their bodies. The toxin of the plant acts like a defense mechanism for the caterpillar and does not affect it. If a bird eats the caterpillar, the toxin will affect the bird,” says Paranjpe.

She adds that insects cannot be considered in isolation but in relation to their ecosystem. “I feel that, by doing the survey, we have not only documented biodiversity but have also opened up a lot of other questions about insects interactions with plants and food webs that we are slowly starting to understand,” she says.