Susceptibility of two-spotted red spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) to entomofungal pathogens.

Studies were conducted on the susceptibility of red spider mite. Tetranychus articue (Koch) against different fungal pathogens belonging to the group Deuteromycetes like Beullveria bassiana, Paecilomyees fumosoroseus, Verticillium leeanii and Hirsuella thomposonii . In bioassay studies B. bassiana , isolated from naturally infected population of T. urtieae was found to be more virulent against T. Urticae adult. The lowest LC 50 (3.61x10 6 conidia/ml) and LT 50 value (85.4 hours) were recorded for B. bassiana , followed by V. iecanii (6.30 conidia/ml and 106.3hrs), H. thompsonii (19.91 conidia/ml and 124.3hrs) and P. fumosoroseus (29.92 conidia/ml and 119.5 hrs). In glasshouse studies on French beans, spore suspension of V. lecanii (@ 1x10 12 /ha) was found to be more effective in reducing mite population up to 87. 44% after 10 days of spraying followed by B. bassiana (85.47%), P. fumosoroselis (84.22%) and H. thompsonii (80.47%). In contrast, highest population reduction of 87.50%. was recorded in dicofol. V. lecanii proved to be all effective fungal pathogen against RSM in reducing population under glasshouse condition probably because of their rapid colonizing capacity in soft bodied micro-arthropods inhabiting humid microclimate. Effective commercial formulation of V. lecanii could be a suitable fungal pathogen for the management of red spider mites in different field crops.