Environment

Why India's Insects Are Disappearing

According to scientists, 40% of insect species are likely to become extinct globally in the coming years. Indian entomologists agree that India is already witnessing a slump in insect numbers.

When was the last time an insect fell in your soup? Or down your collar under a bright street lamp? Insects rarely land on window panes on a rainy night or buzz about in the sun, nowadays. If you think that’s a good thing, think again.

There are approximately 5.5 million insect species buzzing, creeping and crawling across planet earth. However, a scientific review of records recently published in the journal Biological Conservation reveals that up to 40% of insect species worldwide are likely to become extinct in the coming years. And, entomologists say that is bad news.

Our knowledge of the services that insects provide to the ecosystem is limited. In fact, nearly 89% of the global insect population has not even been named, said former director of the Zoological Society of India, P.T. Cherian, who is among the many scientists who believe that India too is part of the decline of insects being witnessed globally.

“In the early 70s, I visited Coonoor several times in search of this interesting leafhopper of the genus Gunhilda that had earlier been recorded from that place. But neither my students nor I, or anyone else looking for it, has found it ever since,” shared C.A. Virakthamath, the 76-year-old doyen of contemporary Indian entomology, Professor Emeritus at Gandhi Krishi Vignana Kendra (GKVK), Bengaluru, in Karnataka, and an authority on leafhoppers. A complete genera of leafhoppers has disappeared in India.

Also read: A Bug’s World: the Story of How Wings Set Insects Free to Colonise Earth

“You don’t hear insects as you would before,” Rohini Balakrishnan, chairman, Centre for Ecological Studies at the Indian Institute of Science (IISc), Bengaluru, told Mongabay-India. Balakrishnan specialises in insect acoustics, particularly crickets and tettigonids. “Their numbers are diminishing, and that should be a cause for worry,” she added, underlining the growing urbanisation as one of the reasons.

Other Indian entomologists have similar tales to tell. According to Prathapan Divakaran, an entomologist from College of Agriculture in Vellayani, Thiruvananthapuram in Kerala, two species of flea beetles that he had collected from the Botanical Garden at GKVK campus in Bengaluru in the 90s, are now locally missing. An expert on flea beetles, who has described 80 new species and seven new genera, Divakaran says: “I have also not been able to locate several genera described in the records on fauna from British India.”

Director of the National Bureau of Agricultural Insect Resources (NBAIR), Bengaluru, Chandish Ballal said that the same seems to be happening with the Ichneumonid wasp, Campoletis chlorideae, an important pest controller against moths infesting chickpea crop. Past published records showed the presence of 70% of these wasps on chickpea pods. Yet in 1990, when she was studying the wasp for her doctoral work, Ballal barely recorded 20% of these wasps on chickpeas. Could this be attributed to the use of pesticides? The lack of records leaves this question unanswered.

Meanwhile, V.P. Uniyal from the Wildlife Institute of India in Dehradun, Uttarakhand, has observed a drastic decline of fireflies. He is now planning a project to monitor their status.

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