Updated: March 10, 2016 7:58:23 am
For the first five years after its introduction in India in 2002, ‘Bollgard’, the genetically-modified Bt cotton developed by Monsanto, effectively controlled bollworm insect pests. Yields increased by 67 per cent and use of insecticides — which couldn’t contain the extensive damage from American bollworm prior to that — decreased by 33 per cent.
True, yields may have also gone up due to other factors: a 36 per cent increase in fertiliser use; doubling of area under hybrids; increase in irrigated cotton area in Gujarat; and the effects of seed treatment with imidacloprid and introduction of at least six new insecticides to control sap-sucking insects.
The scenario, however, changed after the introduction in 2006 of ‘Bollgard-II’ Bt cotton, containing a second gene, Cry2Ab, derived from a soil bacterium called Bacillus thuringiensis, in addition to the original Cry1Ac gene of ‘Bollgard’. Average seed-cotton yields per hectare in India have stagnated at 1,500-1,700 kg since 2006, despite the share of Bt hybrids in overall acreage rising from 38 per cent to 96 per cent and fertiliser usage rising by 70 per cent. More disturbingly, insecticide usage has gone up by 92 per cent, because of increased sap-sucking insect pest attacks.
The blame for this can be laid largely on the whopping 734 Bollgard-II hybrids — compared to just about 20 in the first five years — being approved to saturate almost the country’s entire cotton area. The bulk of these hybrids were highly susceptible to leaf hoppers and whiteflies. Increased insecticide use only accelerated the development of ‘insecticide-resistance’ in these pests. Even more worrisome was the pink bollworm, which was almost forgotten in India after 1980, but made a reappearance to rapidly develop resistance to Bollgard II.
The main reason why India has been unable to harness the full potential of Bt cotton technology is that it got caught in the hybrid trap. Strange but true, only India cultivates Bt cotton hybrids, whereas other countries grow only ‘straight varieties’. The general perception is that hybrids give higher yields. With 95 per cent of India’s cotton area under Bt hybrids, its yields should have been the highest. The truth is that India’s seed-cotton yields are way below the average 2,700 kg/hectare for the rest of the world, despite these countries predominantly cultivating straight varieties. In fact, Pakistan and China rejected the idea of ‘Bt-cotton hybrids’ and Monsanto doesn’t have a presence there.
India’s average yield is low mainly because of the unsuitability of hybrids for rain-fed regions which constitute 60 per cent of India’s cotton area. The crop duration, too, is longer, at 7-8 months, compared to 5-6 months in other countries. The plant density in hybrids of about 11,000 to 16,000 plants per hectare is a tenth of the global average based on straight varieties. High-density planting is simply unviable with expensive and bushy hybrids producing more foliage. Because of low plant population in hybrid cotton fields, each plant is required to produce more number of bolls, which extends into long duration. Long duration isn’t good for rainfed conditions, where the crop suffers moisture and nutrient stress, especially during the critical flowering and boll formation stages from the 4th to 7th months, resulting in lower yields. Hybrids generally perform well under irrigated conditions with high chemical inputs, but even there long-duration hybrids provide opportunities for insects like pink bollworms to proliferate in multiple cycles. These feed mainly on developing cotton seeds in green bolls.
Bt cotton is a powerful and useful technology to control bollworms: American bollworm, pink bollworm and spotted bollworm. But since the technology in India was available only with private companies, they ensured it was incorporated only into hybrids and not in straight varieties enabling farmers to reuse the farm-saved seeds. They were left with no choice, but cultivate hybrids whether or not these suited their soils. In the irrigated belt of Punjab, Haryana and Rajasthan, the acreage under hybrid cotton was negligible prior to the introduction of Bt hybrids. But by 2008, the entire cotton area in the region was covered by commercial Bt-cotton hybrids, replacing all straight varieties. These included excellent publicly-bred high-yielding varieties tolerant to insects and diseases. Unfortunately, with the proliferation of hybrids since 2006, Punjab’s cotton crop suffered heavy infestation of whitefly last year. Nor have yields gone up much. Yields in Pakistan under similar conditions have been 20 to 30 per cent higher than in the adjoining North-West Indian states.
Bt cotton technology was messed up in India by the private seed industry, which underestimated the power of bollworms and undermined the need for implementing proactive insect resistance management strategies. No wonder, a small worm called ‘pink bollworm’ has brought Bollgard-II technology down to its knees. It needs to be asked why the pink bollworm developed resistance to Bt cotton only in India within just 5-6 years, and not elsewhere in the world. The industry is instead blaming the Indian farmer for not planting non-Bt cotton seeds as refugia. But this could only have marginally delayed resistance development. China doesn’t have any recommendation of ‘refugia’ planting along with the regular Bt cotton seeds. Yet, the pink bollworm hasn’t developed resistance despite 18 years of Bt-cotton cultivation there.
There are three factors unique to Bt cotton in India, all of them related to hybrids, that have accelerated the development of pink bollworm resistance to Bollgard-II.
* 1 Bt toxins are absent in 25 per cent of seeds in the bolls of hybrid Bollgard plants and in over 6 per cent of seeds in the bolls of Bollgard-II plants. The young bollworms can, then, survive initially on non-Bt seeds and subsequently, as they get older, feed on the rest of the seeds containing Bt toxins. This accelerates resistance development. When Bt technology is available in ‘straight varieties’, all the developing seeds in bolls contain the toxins. Therefore, resistance development is delayed.
* 2 Hybrids take longer time to produce more bolls/plant, thus providing continuous food source that help pink bollworm proliferate in multiple cycles and adapt to Bt toxins.
* 3 More than a thousand Bt cotton hybrids were approved in India without proper agronomic recommendations. These, in a matrix of combinations, provided synchronous and overlapping flowering and fruiting windows over a long stretch of time to support pink bollworm populations, thereby accelerating resistance development.
Next in waiting is the impending resistance threat from the most dreaded American bollworm. It is clear that for the next five years, there are no new genetically-modified solutions in the offing. One immediate option under the circumstances is for seed firms to explore the sale of Bt straight varieties under high density planting. All of them have such varieties that they use as parents for hybrid development. Also, they must promote only a few Bt cotton hybrids of 5-6 months duration. These can escape pink bollworm attacks occurring during November-February in central and south India.
Over the past five years, CICR has been pursuing non-Bt ‘desi’ cotton cultivation as a sustainable alternative option, especially in rainfed tracts. Our results have shown that high yields with low production costs can be obtained with short-duration, early-maturing and compact varieties even in the rainfed regions of Vidarbha and Telangana. The crop could also escape bollworm attacks for most part of the season. Besides, CICR has converted around 20 of the elite public sector cotton varieties into Bt. These would be tested this year in Maharashtra and Telangana under multi-location trials to identify the most suitable Bt varieties for rain-fed tracts. Their seeds could be available from 2017 or 2018 onwards at low cost. Since the Bt toxins would be in a homozygous condition in the straight varieties — i.e. in all the seeds in the bolls — they would effectively combat the American bollworm and escape pink bollworm because of short duration. They will also have better yields because of high-density planting.
Despite the big challenges ahead for cotton, the battle is not lost. We can consolidate our ammunition to tide over the next 4-5 years, if science receives precedence over commercial interests at least now.
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