Evaluation of fungal pathogens, Fusarium semitectum Berk. and Ravenel and Hirsutella thompsonii Fisher against red spider mite, Tetranychus neocaledoni-cus (Andre) of okra under laboratory and greenhouse conditions

Abstract

Efficacy of fungal pathogens, Fusarium semitectum Berk. and Ravenel and Hirsutella thompsonii Fisher was evaluated against red spider mite, Tetranychus neocaledonicus (Andre) of okra under laboratory and greenhouse conditions. Among the treatments evaluated under laboratory conditions, the highest mortality of 78.20 and 88.34 percent adults and immatures, respectively was recorded at 2.10 x 10⁹ spores per ml of F. semitectum, whereas it was 82.05 and 92.31 per cent adults and immatures, respectively in case of H. thompsonii at 4.60 x 10⁸ spores per ml. Among the twelve treatments evaluated under greenhouse conditions, H. thompsonii 4.60 x 10⁸ spores per ml, F. semitectum 2.10 x 10⁹ spores per ml + H. thompsonii 4.60 x 10⁸ spores per ml, H. thompsonii 4.60 x 10⁸ spores per ml + dicofol 0.025% and F. semitectum 2.10 x 10⁹ spores per ml + H. thompsonii 4.60 x 10⁸ spores per ml + dicofol 0.025% were found to be on par with each other with a cumulative percent mortality of 81.20, 81.48, 81.21 and 82.59 percent, respectively. By testing the field efficacy of F. semitectum and H. thompsonii against T. neocaledonicus, these fungal pathogens can be used as potential biocontrol agents for the sustainable management of mites on okra. Hence the present study evaluates the potentiality of F. semitectum for the management of T. neocaledonicus by comparing with the well-known acaricidal fungus, H. thompsonii.