An awareness drive for nocturnal wonders

With the Capital’s insect fauna highly neglected, Indian researchers have documented over 300 moth species in an attempt to create awareness and conserve their dying biodiversity 

author_img Dyuti Roy Published :  23rd October 2021 03:16 PM   |   Published :   |  23rd October 2021 03:16 PM
A species of Moth

Spirama spp

India’s urban cities are nothing short of concrete jungles. However, amid such spaces, there are green landscapes that—though barely recognised—that are teeming with insect diversity. This is true even for Delhi. While birds and butterflies are often studied, other groups of insect fauna are neglected.

Keeping this in mind, along with noticing a lack of published literature in urban centres “despite the increased need to monitor insects at sites with high levels of human disturbance”, the National Pusa Collection (NPC-IARI)—a part of the Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi (ICAR-IARI)—decided to study nocturnal moths that are a part of the insect biodiversity. Important members of the food chain, moths are a primary food source to many insects. These pollinators also help in ecological balance. 

Eudocima materna

A recently-conducted study of insect diversity in Delhi—Moths of Delhi, India—was published in the Biodiversity Data Journal. It identifies 338 moth species from 32 families spanning 14 super families from a survey performed using eight years of light trapping data (2012-2020). The researchers also examined the 2,000 specimens from the NPC-IARI records that date back to 1907. Field surveys (for a period of 73 nights) were conducted by setting up light traps at ICAR-IARI, Pusa, Rashtrapati Bhavan, and Asola Bhatti Wildlife Sanctuary. Using a 160W Mercury-Vapour bulb, these light traps were set for five hours from 6pm.

Of the 338 species, the major sightings of moths included:

-Hippotion celerio or the silver-striped hawkmoth
-Erebus macrops or the common owl moth
-Cephonodes hylas or the coffee bee hawkmoth
-Eudocima materna or the dot underwing
-Acherontia styx or the lesser death’s head hawkmoth (also known as bee robbers, as they are known to steal honey from bee hives)

Insect populations are reportedly plummeting all across the world because of habitat loss. As urban cities conduct tree felling so as to make room for linear infrastructures such as buildings, roads, dams, among other such public work systems, there has been a huge loss in biodiversity. According to the study, Sohail Madan, Center Manager, CEC-Asola Bhatti Wildlife Sanctuary (ABWLS) Delhi, BNHS, points out, “In a city like Delhi, chemical poisons such as pesticides and insecticides are used as a blanket treatment over all green spaces. This causes harm to even the beneficial insects. Moreover, especially for nocturnal insects like moths, light pollution in urban environments is greatly affecting their behaviour and life cycle. A moth, which looks at the moon for direction at night, is distracted by artificial lights. Since light pollution is not quite highlighted, many are unaware of the harmful effect it has on fauna.” 

The recent study conducted by the entomologists can be considered as a first step towards making citizens more aware of the insect fauna. In fact, there are only very few researchers of Urban Entomology in the country. While many researchers have documented the fauna of the city, the insect populations have been highly neglected. The eight-year-long study is, therefore, in a way, a process of conserving this depleting biodiversity.

“As one of the most polluted cities in India, no one speaks of the effect of pollution on insects along with humans. Someone has to speak for them,” says Shashank Pathour, Entomologist, NPC-IARI. “In Delhi, the fact that there is such little information existing about moths only shows that far more studies are necessary,” says Sanjay Sondhi, an author of the study and a member of Titli Trust, a not-for-profit nature conservation organisation. Moths of Delhi, India was, therefore, an attempt to make people understand the need to conserve natural lush green spaces. Reducing the use of pesticides and ensuring that one has native plants in their homes is equally important. However, in the recent past, many citizens have started participating in nature walks to document butterflies in the city. Pathour also points out that this is actually exciting, and the journey towards awareness as well as the conservation of the insect fauna has already begun.