Abstract

Field evaluation of pesticide tolerant strain of Cotesia flavipes Cameron, a gregarious larval endoparasitoid of the maize stem borer, Chilo partellus (Swinhoe) was carried out and the economics of such evaluation was worked out. Releases of the pesticide tolerant parasitoid strain, prior to application of pesticide or after application resulted in significantly higher net returns and yield, as compared to the releases of susceptible parasitoid strain and untreated control. Four releases of the tolerant parasitoid at 2000/ha at 500 per release registered maximum number of parasitized cocoons (52.6 per larva), higher yields (4019 kg/ha) and net profits (Rs. 7807 kg/ha), followed by two releases of the tolerant strain with two sprays of insecticide (40.8, 3809 kg/ha and Rs. 6847/ha, respectively). The insecticidal treatment gave higher net profits and yields than all other treatments. However, the additional costs, ecological hazards and pesticide residues (likely to occur) do not outweigh the benefits of biological control.

Key words: Cotesia flavipes, Chilo partellus, population, pesticide tolerance.