Evaluation of mycoacaricides against two spotted spider mite, Tetranychus urticae Koch on jasmine (Jasminum sambac Ait.)

An investigation was carried out in field conditions at two different locations i.e., Vadipatti and Allanganallur blocks of Madurai district of Tamil Nadu to evaluate the bio-efficacy of certain commercially available mycoacaricides against two spotted spider mites Tetranychus urticae Koch on Jasmine (Jasminum sambac Ait.). From the cumulative mean data of this study it was found that among the mycoacaricides evaluated, Beauveria bassiana (Bals-Criv.) Vuill. @ 1 × 10⁸ CFU/g and Lecanicillium lecanii (Zimm.) Zare & W. Gams @ 1 × 10⁸ CFU/g recorded the highest per cent reduction of eggs (59.99 and 58.61% at Vadipatti block and 57.20 and 55.78% at Alanganallur block) and mites (63.39 and 61.98% at Vadipatti block and 59.44 and 58.51% at Alanganallur block) respectively, which were statistically on par in their bio-efficacy against T. urticae on J. sambac. Regarding the flower yield; amongst the test mycoacaricides, the highest per cent increase in flower yield was recorded in case of B. bassiana @ 1 × 10⁸ CFU/g (56.20% at Vadipatti block and 55.33% at Allanganallur block) and L. lecanii @ 1 × 10⁸ CFU/g (54.89% at Vadipatti block and 55.01% at Allanganallur block) along with the highest cost benefit ratio of 1: 1.83 and 1: 1.59 at Vadipatti block and Allanganallur block respectively and 1: 1.61 and 1: 1.50 at Vadipatti block and Allanganallur block respectively, which were statistically at par. Thus, B. bassiana @ 1 × 10⁸ CFU/g and/or L. lecanii @ 1 × 10⁸ CFU/g can be recommended for the management of T. urticae infesting Jasmine as a substitute to synthetic chemical acaricides due to their host specificity, safety to natural enemies with no toxic residues.