Field Evaluation of Trichogrammatids for the Control of Helicoverpa armigera (Hubner) on Tomato

Trichogramma chilonis Ishii, T. pretiosum Riley and T. brasiliense Ashmead were field evaluated at three different dosages (50,000, 75,000 and 100,000/ha)" against Helicoverpa armigera (Hiibner) on tomato. No significant difference was observed in mean egg count in all the treatments. However, significant difference was observed in larval population and lowest mean larval population (0.5 larvae/5 plants) was recorded in T. chilonis @ one lakh/ha dosage. Highest parasitism (41.07%) was recorded where releases of T. chiolli s were made @ one lakh/ha, and it was on par with the treatment of 75,000/ha of T. chiolli s (40.0()%). Lowest fruit damage (8.01 %) was recorded in treatment where T. chilollis was released @ one lakh/ha, which was followed by the release of T. chilonis @ 75,000/ha (9.20%), one lakh/ha of T. brasiliellse (11.66%), and T. pretiosum @ 1,000,000 and 75,000/ha (10.88 and 11.82%, respectively). Highest (261.07q/ha) yield was form treatment of T. chiloni s @ one lakh/ha, followed by T. chilonis 75,000/ha (248.27q/ha).