Management of Helicoverpa armigera (Hübner) on tomato using insecticide resistance egg parasitoid, Trichogramma chilonis Ishii in farmers’ field

A multiple insecticide tolerant strain of beneficial egg parasitoid, Trichogramma chilonis with several folds of tolerance to six different insecticide groups was developed for suppression of Lepidopteran insect pests on vegetable crops. Tolerant strain parasitized significantly more pest eggs and survived long compared to the susceptible strain under sprayed condition. The tolerant strain could parasitize more eggs during winter (50.8%) compared to summer (39.0%), whereas no parasitism was recorded by susceptible strain under sprayed system in net-house. The activity of detoxifying enzymes, viz., glutathione S-transferases and carboxylesterase was significantly high by 2.13-fold and 1.5 to 9.0-fold in tolerant strain. Field evaluation of the strains in different geographical locations in India, on tomato resulted in increased yields by 816, 2400 and 1500 kg/acre and reduced insecticidal application by 20–65% and per cent benefit of Rs. 9,000 to 20,000/acre to farmers.