Failure of control measures against Heliothis armigera (Hübner) infesting tomato in heavy pesticidal application areas in Delhi and satellite towns in western Uttar Pradesh and Haryana (India)

A survey of tomato fields in Delhi and adjoining areas of Meerut and Hapur in western Uttar Pradesh, and Sonepat and Panipat in Haryana (India) during 1995–96 was undertaken to estimate the damage caused by the fruit borer, Heliothis armigera (Hübner). Most of the farmers used two Indo-American hybrids, viz., Rashmi and Rupali. The farmers in Delhi commenced prophylactic spraying in the 2nd or 3rd week of January, while those in Meerut, Hapur, Sonepat, and Panipat started spraying in the 2nd or 3rd week of February. Almost every type of insecticide available in the market, viz., cypermethrin, deltamethrin, fenvalerate, endosulfan, monocrotophos, phosphamidon, malathion, dimethoate, methyl parathion, phosalone and Donnet was used. The fungicides included Dithane M-45, bavistin and copper. Bacterial preparation ‘Halt’ (B.t.) and neem oil were also applied. The concentrations used were generally higher than the recommended doses. They combined two to three insecticides or even fungicides and Halt. Many farmers sprayed at weekly intervals, while sometimes spraying was done at 4-day intervals. The total number of sprayings usually ranged from 12 to 16. The maximum spray was given in Green Belt area of Delhi where farmers sprayed tomato crop even up to 20 times. The total amount of pesticide consumption ranged from 8 to 14 kg a.i. per hectare in different areas. During early March, the infestation of H. armigera was found in flowers, flower buds and young developing fruits, while by the end of March, the green fruits were badly damaged. At the time of first picking made in the end of March or early April, the infestation varied from 70 to 80 per cent or even more in spite of heavy application of pesticides. By the 2nd week of May, the infestation started declining and was 13–18 per cent in the 3rd week of May. In the 4th week of May, it was only 3 to 5 per cent. In April, 5 to 20 per cent tomato plants were also found affected by virus disease. Thus, the overuse/misuse as also indiscriminate use of pesticides resulted in failure of control of the tomato fruit borer. This suggests that H. armigera, perhaps, has now developed resistance to insecticides in aforesaid pockets in northern India as well. The reported occurrence of resistant strain of H. armigera in South India has already been well documented. The otherwise inescapable total failure'of the crop can best be avoided by adopting integarted pest management with less dependence on pesticide applications.