Why the absence of leafhoppers swarming around light bulbs is bugging Bengal environmentalists

For long they dominated the autumnal nights in Bengal’s countryside to urban centers, swarming around lights, creating nuisance.

To take cover from their invasion, people would often switch off the lights early, only to find tiny carcasses littered all around the house the next morning.

They would cause greater distress to farmers, destroying their rice crops.

Yet the arrival of these ubiquitous tiny mites-like insects called green leafhopper was awaited as it marked the advent of the autumnal festival of Kali Puja, also called Shyama Puja.

So much so that the insect has even been named in Bengali after the festival – Shyamapoka, Shyama being the other name of the dark-skinned deity.  Poka is a Bengali term for insects or worms.

The sap-sucking, slender and small hind-legged insect– size ranging from 1/8th of an inch to 1/4th of an inch long belongs to the Cicadellidae family and is capable of flying as well as jumping.

They have been regular visitors between October and November, around the time Kali Puja and Diwali take place, particularly in rice-producing states of India.

This year though, the seasonal invader has so far not intruded into the night space of humans even after Kali Puja and Diwali.

“Even last year they had arrived in hordes, damaging rice crops by sucking plant sap at day time. In the night, they were major irritants at home, flocking around electric bulbs, television and even mobile screens,” says Paru Murmu, a farmer from a remote tribal village of Dewanganj in Birbhum district.

“Strangely, they are hardly visible so far this year,” Murmu added.

“The presence of the once-ubiquitous shyamapoka—the green leafhopper—has diminished in their former fiefs of Jhargram, West Midnapore and Bankura,” wrote The Telegraph in an edit piece on November 13.

Murmu, however, is not viewing the absence as a good riddance. Being close to nature, he knows the importance of these otherwise irritating creatures for our ecology.

Over one million species of insects have been discovered and described but it is estimated that there may be as many as 10 million species on earth, according to London-based Royal Entomological Society.

There are approximately 1.4 billion insects for every person on Earth, the society says, and the total weight of all the insects is about 70 times more than all the people.  They make up to 90 per cent of all species of animals on the planet and more than half of all living things.

They are “essential” for the proper functioning of the mechanism that sustains life on earth being food for other creatures, pollinators and recyclers of nutrients, environment scientists say.

“Disappearance of any insect from our ecosystem is a matter of concern because they form the base of the food pyramid and help plants to pollinate,” explained Dipayan Dey, Chair, Research and Planning, South Asian Forum for Environment (SAFE).

In 2019, Biological Conservation reported that 40 per cent of all insect species are declining globally and a third is endangered.  The rate of extinction is eight times faster than that of mammals, birds and reptiles.

The total mass of insects is falling by a precipitous 2.5 per cent a year, the report said, suggesting they could vanish within a century.

Overuse of pesticides, habitat loss and climate change are threatening their existence, Dey told The Federal. Their annihilation could lead to a food crisis, he added.

This is precisely why Murmu does not want the irritating green leafhoppers to disappear completely, meeting the same fate as many of the insect species.

This, despite the fact that they feed on sap of paddy panicles and are vectors of bacterial and fungal plant pathogens.

Leafhoppers play multiple crucial roles in the ecosystem, including that of pollinators, Dey said. Insectivorous birds and other organisms, like ants, also feed on the leafhoppers.

Dey, however, said it is too early to write the epitaph of the tiny creature. “Their arrival might have been delayed this year due to some climate change impacts that the state has witnessed.”

Dry and cooler temperature is required for the leafhoppers to grow. But this year, there was high rainfall in late September and October, impacting the larvae.

Moreover, the heavy autumnal rain has also dropped paddy yield in the state, which in turn affected the population of leafhoppers, which thrive on rice plants.

“There has been no real nip in the air even in mid-November due to the impact of cyclone Sitrang [it made landfall on October 25] that has pushed back the winter. All these climatic conditions impacted the advent of the autumnal creature,” Dey explained.

“I was in Sunderbans on Sunday. There I saw the insects. I think their arrival has just been delayed,” he pointed out. In the same breath he added that its population is definitely declining, which is not a good sign either.

Earlier, even in cities like Kolkata they were a common sight in autumn or what is left of it, he said. This is not the case now because paddy is no longer grown in the vicinity of the cities.

For obvious reasons most urban dwellers don’t seem to miss the leafhoppers much. In fact, many have hardly noticed the absence. Some are even amused that the absence of a small insect could bug conservationists so much that it’s making newspaper headlines.

“I recently saw one headline and at first thought what’s so special about it. When I started reading about it, I was reminded of instances when we would get shouted at for leaving the door or window open with the lights on. It took me on a nostalgia trip back to childhood,” said Shrabani Basu, a college-goer and a resident of posh Ballygunge in Kolkata.

Halfway through the newspaper article, she realised the importance of this small insect, or for that matter, any other living organism.

“Everything on Earth has a meaning and is important for our survival, no matter how irritating or pleasing. There is no running away from the truth that climate change is here. Yet we hardly understand or care about its impact,” she added.