Dattatreya Maruti Gosavi is confident that his four acres of sugarcane will yield at least 240 tonnes. Last year, the 45-year-old farmer from Yedgaon village in Pune’s Junnar taluka could harvest only 180 tonnes, as the crop on three acres was damaged by white grub (Holotrichia serrata) insect larvae. This year, he has controlled its infestation to just 0.5 acres — thanks to a unique ‘beetle buyback’ programme of the Shri Vighnahar Cooperative Sugar Factory near Junnar.
“My suru cane (planted in November 2017) is almost ready for harvesting. This time, there is no humani (white grub) on 3.5 acres and only a little bit on 0.5 acres (which is a separate land parcel),” says Gosavi, who also grows onion, tomato and other vegetables on two out of his total six-acre holding.
Cane growers in Maharashtra are now faced with challenges of not just drought and payment by mills due to low sugar realisations (<https://bit.ly/2QwRM0G> ), but also from white grub attacks. The agriculture department has reported infestation of the pest in about 1.54 lakh of the state’s overall 11 lakh hectares cane area in the 2018-19 sugar season (October-September). It is particularly severe in Solapur and Pune districts, with yield losses ranging from 25 to near-100 per cent in
White grub basically refers to the larvae of beetles (scarabaeidae family) that lay eggs on fields around June. These eggs hatch into larvae in 10-15 days. The larval stage lasts for up to seven months, after which the grubs pupate. The adult beetles emerge from the dormant pupae stage with the first monsoon showers in the following June. They then lay eggs, completing their one-year or so lifecycle.
For cane growers, the larvae are the most dangerous. The soil-inhabiting white grub survives by chewing the roots of the growing plant. What’s worse is that the effects of this below-the-ground feeding are visible only when the cane starts wilting — there is an initial yellowing of the leaves, followed by drying and lodging of the plant. By then, it’s too late for the farmer to take control measures.
The usual recommended method to control infestation is application of insecticides such as phorate, chlorpyriphos and fipronil-imidacloprid combination. But farmers like Gosavi are increasingly reluctant about using these chemicals, given the precautions to be taken in their spraying and the ability of pests to develop resistance. The Pune-based Vasantdada Sugar Institute (VSI) has developed a biological control solution comprising a ‘BVG’ cocktail of three insect-pathogenic fungi: Beauveria bassiana, Verticillium lecanii and Metarhizium anisopliae.
However, Shivajirao C. Deshmukh, director-general of VSI, emphasises that relying on chemical or biological agents may not be enough. White grub control calls for an integrated approach — which includes intervening in the lifecycle of the beetle and preventing it from laying eggs at all.
The Shri Vighnahar sugar mill has been facing white grub problems in its entire 30,000-odd acres cane area, spread between Junnar and Ambegaon talukas of Pune district, since 2003-04. The factory decided to go for integrated control, including through incentivising and actually paying farmers for every kg of beetles caught.
The adult beetles emerge from the ground in June-August after the monsoon rains, mainly between 7 to 7:30 pm. These insects then fly to the nearest neem, subabul or mango trees within 2-2.5 km radius of the cane fields and mate. Once that is over, the females fly back to lay eggs underground before the break of dawn.
“During this time window, the beetles can be caught simply by shaking the trees. We have encouraged our farmers to adopt this approach as an effective way to deal with the menace,” explains Satyashil Sherkar, chairman of the Shri Vighnahar cooperative. The mill, through a systematic campaign launched last May, got farmers to make shallow rectangular pits under the trees and fill these with water mixed with kerosene to catch the beetles. Farmers bringing the dead insects to the mill were paid at the rate of Rs 300/kg. Also, light traps were set up near the trees to attract the beetles.
In 2018 alone, the mill collected 29,63,300 beetles and paid its farmers a total of Rs 9,87,766.50 for the same. “The previous year, we had paid Rs 86,052 for 2,72,500 beetles. The yield losses in the 2017-18 season prompted farmers to be extra vigilant this time,” he notes. The factory’s beetle-buyback programme dates back to the mid-2000s, “but we stopped it twice, during 2010-13 and 2015-16, only to restart last year, as the pest returned with a vengeance”.
Sherkar pegs the white grub infestation in the factory’s cane area at over 5,000 acres in the current season. “But the yield losses even here are between zero to 25 per cent, while more than 50 per cent only in 100 acres,” he claims. At the same time, the severe drought conditions in Maharashtra now could result in a major attack during the 2019-20 crushing season, since the grubs tend to proliferate in dry and arid soils. “We will have to be even more aggressive in the coming June,” admits Sherkar.
Gosavi, on his part, is happy to see his cane suffer less damage from white grub and also earn Rs 18,000 from selling beetles. “Our area is notorious for snakes and leopards. Beetles add to our woes. For us, the choice is to either catch these, which is hardly fun, or allow our cane to be destroyed, which is a disaster” he sums up.