Efficacy of different techniques for the release of Trichogramma chilonis Ishii, parasitising sugarcane internode borer, Chilo sacchariphagus indicus (Kapur)

Different techniques for the release of Trichogramma chilonis Ishii viz., ice-cream cup open/closed, plastic disposal cup open/closed, thermocool cup and loose egg exposure methods were compared with conventional release techniques involving tying of paraitized egg card by thread on to the leaf sheath or directly stapling the card on the lower ventral surface of middle leaf. The field trials were conducted during 1994–95 and 1995–96 at the Sugarcane Research Station, Cuddalore (India). In the first season, release of the parasitoid through closed cup methods (ice-cream cup and plastic disposal cup) and loose egg exposure procedure recorded higher per cent emergence, viz, 70.8, 70.3 and 74.1 as against the tying (61.0%) and card stapling (60.7%) to a sugarcane plant. A similar trend of parasitoid emergence was recorded in these release techniques during the next year. The per cent increase of emergence of parasitoids in the aforesaid three techniques varied from 15.2 to 21.5 over the conventional practice. The increased emergence may be attributed to the safety afforded against sunlight, moisture, and natural enemies in modified techniques.