Cotton Curse: Pheromone-based mating disruption technology may help control pink bollworm

Experiments show 90% reduction in losses, improved yield

By Himanshu Nitnaware
Published: Monday 30 October 2023
A farmer shows a cotton fruit damaged by pink bollworm. Photo: Vikas Choudhary / CSE__

This is the seventh story in a series about pink bollworm attacks on Bt Cotton in the North Zone, comprising Punjab, Haryana, and Rajasthan.

Farmers across cotton-growing states are struggling to manage the pink bollworm (PBW) pest that is wreaking havoc, resulting in heavy economic losses. Even the genetically modified pest-resistant cotton variety, Bt Cotton (Bollgard II seed), which was created to resist PBW, is no longer effective in keeping them away. 

Ground visits by Down To Earth (DTE) revealed farmers in Haryana, Rajasthan and Punjab were facing yield losses of 80-90 per cent. 

PBW is a worm that damages parts of the developing cotton fruit by laying eggs on it. The larvae burrow into the rounded sac of seeds called bolls to feed on the seeds. The pest is concealed inside the green boll and is protected; thus, spraying of pesticides and insecticides does not affect it after it penetrates the fruit.

Read more: Untangling India’s Bt cotton fraud

YG Prasad, director, ICAR-Central Institute for Cotton Research, Nagpur told DTE that scientists are working to identify new genes effective against PBW. 

“We have observed 8,000 germplasm accessions in field evaluations to identify sources of natural resistance that will help fight PBW, but it is likely that a transgene or gene editing will have to be tried,” Prasad said.

Even after the gene is identified and a seed variety is developed, it would still take time to undergo various trials, create a public-private partnership and seek approval from the Review Committee on Genetic Manipulation and Genetic Engineering Appraisal Committee, he added. 

“Effective monitoring and timely adoption of a crop-window-based integrated pest management (IPM) strategy is the immediate solution,” Prasad suggested as the immediate solution.

However, a group of scientists is experimenting with a technology that has proven to be successful in the United States. The technology is called PBKnot or PB Rope L, said Bhagirath Choudhary, founder-director for South Asia Biotechnology Centre, Jodhpur, Rajasthan.

“The technology helped the US tackle the pest that was affecting farmers for 100 years. The pest was eradicated in 2018 after its implementation in 2008,” he said. 

Read more: Why are pests developing resistance to Bt cotton in Telangana, Andhra Pradesh?

According to Choudhary, PBW annually affects lint quality and lowers yield on about 12 million hectares of cotton crops worldwide. The Centre has been experimenting with technology in India since 2022 and has received enormous success, resulting in a 90 per cent reduction in losses, he said.

The technology received for the IPM strategies for controlling the population of PBW received approval in India from Central Insecticide Board and Registration Committee for the first time in 2019-20.

“The technology is being experimented with under Project Bandhan and working closely with Krishi Vigyan Kendra, agriculture universities and local institutions. It involves disrupting the mating cycle of the moths,” he said.

The technology involves using a 20-centimetre polyethylene hollow rope that is impregnated with pheromone gossyplure — a chemical emitted by female moths — to attract male moth. 

In natural temperatures, the rope expands and the narrow holes emit pheromones, which released in the air, confuse the male moths and prevent them from reaching the actual female moths, said Choudhary. This, thus, disrupts the mating process and reproductive cycle. The result is a drop in population and reduced damage to crops.

“They are installed after the crop is 45 days old and tied to plants around the border and inside. About 160 such ropes are installed in an acre along the border of a farm and inside with a gap of 25 square metres. The technology is successful on large cotton fields with a minimum area of 40-50 acres,” he said.

Read more: Study points to quality issues in Bt cotton seeds

A pheromone trap is also installed to monitor the activity of male moths, along with checking flowering and green bolls. The method successfully helped assist 90 per cent disruption in 1,100 acres of land across 18 locations in India in 2022, he said.

“It also helped increase yield up to 1.5 quintals per acre with improved lint quality. In 2023, the experiment was being conducted in 710 acres of land in 11 locations in Gujarat, Maharashtra, Telangana and Andhra Pradesh,” the scientist said.

The government of India has to step in to adopt this biotechnology tool and implement it in all cotton-producing zones in India to make it successful on a wide scale, Choudhary added.

Read the first part here, the second partthe third partthe fourth partthe fifth part and the sixth part

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