Climate Change

Locust attack: Excessive pesticide use will take its toll on Thar ecology

The strongest pesticides used to counter locust invasions will leech into waterbodies and crops, say experts

 
By Jitendra
Last Updated: Tuesday 04 February 2020
Photo: Moola Ram Saran

Lethal pesticides used to counter locust swarms invading the Indian side of the Thar desert will irrevocablly harm the fragile desert ecology, experts have said.

As there was no co-ordination with Pakistan when the swarms first invaded its side of the Thar, Indian officials did not prepare properly to tackle the insects.

When they finally invaded India, the government was forced to use the most lethal pesticides, organophosphates (OPs), which will eventually leech into the desert’s waterbodies as well as the next crop, experts warned.

Organophosphates are a group of chemicals that were initially developed as human nerve agents during the 1930s and 1940s to be used by Nazi Germany during World War II.

They were later adapted for use as insecticides. OPs are known to leech into water bodies close to agricultural fields. This can spell disaster for humans, plants and animals.

Officials in the 11 Rajasthan districts that have been affected — Barmer, Churu, Jodhpur, Nagaur, Jaisalmer, Jalore, Jhunjhunu, Sikar, Sriganganagar and Bikaner — admitted to Down To Earth that OPs were used.

“We have not used such a high amount of Chlorpyrifos, an OP, in such a short span of time. This could potentially damage the environment,” Suwa Lal Jat, joint director at the agriculture department of Rajasthan, said.

The Rajasthan government has already directed different departments to assess the damage and its future impact, he added.

Wither procedure?

Ten types of chemicals divided into three categories are recommended to be used for controlling locusts by the United Nations Food and Agriculture Organization (FAO).

The first category is mycoinsecticide (for instance, Metarhizium acridum). This is of low risk to non-target organisms including birds and reptiles which ingest the treated locusts.

The second category is insect growth regulators (like diflubenzuron, teflubenzuron and triflumuron). It is very low human toxicity and is less hazardous in comparison to neurotoxic insecticides although there are some adverse effects on certain non-target organisms, especially aquatic arthropods.

The OPs should be the last resort, according to the FAO.

“The first two categories would have been effective if we would have detected locust infestations early and acted on them. But we acted late and ended up using OPs, that are effective but hazardous,” Chandrashekhar Sharma, a Jodhpur-based scientist trained in controlling locusts, said.

Chlorpyrifos, the OP that Jat talked about, creates a motility rate by 50 per cent within three hours. Another 30 per cent locusts get paralysed and the remaining 10 per cent fall unconscious. The remainder die after flying within 2 km.

Besides delayed government action, there are other reasons for the excessive use of OPs. The locust watch centres (LWCs), the designated government bodies to tackle locust attacks, are usually on the boards of farmer groups.

Orders from the upper echelons of government to these LWCs are to use deadly insecticides to control locusts. OPs are also supplied free of cost.

Last but not the least, farmers who are petrified by seeing the locust swarms devour their crops, want immediate action against the insects. “The locust is a robust pest. Farmers want immediate and effective solutions to deal with them,” Sharma said.

Effects on the Thar

The Thar desert is a rich ecosystem. It has a number of salty lakes like Tal Chhapar in Churu district, Lunkaransar in Bikaner, Gajner Jheel, Kheichan and Bap Thana area of Phalodi in Jodhpur, the Pachpadra, Tirsingdi, Korana, Navai villages of Barmer and the ponds of Jaisalmer.

These are annually visited by migratory birds of many species. Indigenous birds also depend on them.

“It is inevitable that birds will die in the next migratory season as these OPs must have leeched into the water bodies,” Madan Mohan, associate professor of Entomology, Agriculture University Jodhpur, said.

Moreover, crops laced with chemicals can impact exports.

“Our business of cumin export to European countries would be impacted if they found high level of chemical residue,” Dilip Kumar, a project manager working with a cumin exporting company in Barmer, said.

“There should be a regular meeting with Pakistan every month to manage locust attacks,” Jat said. “If Pakistan would have controlled it better then it would not have created mayhem in India. We should have helped them in the management,” he added.  

This is the fourth and concluding part of a multi-part series

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