Management of Insecticide Resistant Helicoverpa armigera (Lepidoptera: Noctuidae) in Cotton in India
Mar 7, 2019
Helicoverpa armigera (Hübner) was responsible for some $500 million of damage in India in the 1997-8. Insecticide resistance levels have been monitored routinely at sites throughout the country since 1992 using discriminating dose assays. Resistance to pyrethroids is ubiquitous and stable at around 50-80% in most areas. Organophosphate and endosulfan resistance is stable at around 20-50%. Carbamate resistance is low. There is currently no significant resistance to Bt. Putting in place effective, economic, insecticide-based programmes that do not exacerbate the resistance problems, is a priority. Field trials from 1992-5 at ICRISAT developed appropriate IPM/IRM practices in pigeonpea and cotton. In 1995-6 these were taken into ‘split-plot’ IPM/IRM farmer trials in Andhra Pradesh (AP). Seed cotton yields were slightly enhanced with a 23% reduction in the number of insecticide sprays and a 57% reduction in the a.i. applied. In expanded trials in 1996-7 trials in AP and Tamil Nadu, insecticide use was reduced by over 40% and yields enhanced by 30%. Components of the package included appropriate varietal selection, seed quality and agronomy and improved spraying practices with quality materials based on scouting to simple economic thresholds. Early season spraying for sucking pests was avoided by the use of systemic seed dressings. The sequence used for bollworms was: Eggs: at low numbers - neem; at high numbers - profenofos, Larvae: 1st round: endosulfan; 2nd round OPs (quinalphos or chlorpyrifos); 3rd round, carbamates (carbaryl); 4th round - pyrethroids (cypermethrin, fenvalerate, deltamethrin or lambda cyhalothrin). In the 1997-8 season farmer participatory demonstrations were undertaken in four states (Punjab, Andhra Pradesh, Maharashtra and Tamil Nadu). In all areas spray applications were at least halved with respect to non-participating farmers and yields rose by at least a third. The work was expanded in the 1998-9 season.