DETERMINATION OF LETHAL CONCENTRATION AND LETHAL TIME OF ENTOMOPATHOGEN Beauveria bassiana (BALSAMO) VUILLEMIN AGAINST Tetranychus urticae KOCH

M. GEROH¹, R. GULATI², K. TEHRI³*
¹Department of Zoology, CCS Haryana Agricultural University, Hisar - 125 004, Haryana, India.
²Department of Zoology, CCS Haryana Agricultural University, Hisar - 125 004, Haryana, India.
³Department of Zoology, CCS Haryana Agricultural University, Hisar - 125 004, Haryana, India.
* Corresponding Author : knkzoology@gmail.com

Received : 16-06-2015     Accepted : 24-08-2015     Published : 01-09-2015
Volume : 7     Issue : 5       Pages : 523 - 528
Int J Agr Sci 7.5 (2015):523-528

Keywords : bioassay, entomopathogen, Beauveria bassiana, Tetranychus urticae, LC50, LT50
Academic Editor : Bhede B.V., Prasad B. Ram, Shalaby Sh. E.M., Ramesha B., Dr Vishwakarma Ramanuj, Shinde Y.A.
Conflict of Interest : None declared
Acknowledgements/Funding : Beauveria bassiana culture (Hyderabad strain) provided by Dr. P.S. Vimala Devi, Directorate of Oilseeds, Hyderabad is duly acknowledged.

The present investigation was undertaken to determine the lethal concentration and lethal time of entomopathogenic fungus Beauveria bassiana against the two spotted spider mite Tetranychus urticae. Higher mortality percentage was observed in Direct Spray Bioassay for eggs, larvae, nymphs and adults as compared to Treated Food Bioassay. Mortality data fitted well to the probit mode as indicated by the small χ2 values. The LC50 values in direct spray bioassay were 3.0×105, 1.4×106, 0.4×107 and 0.3×108 conidia ml-1 for eggs, larvae, nymphs and adults, respectively. The same values in treated food bioassay were 1.3×108, 5.1×109, 1.0×1010 and 2.6×1011 conidia ml-1. This suggested that eggs and larvae were more susceptible to B. bassiana treatment than nymphs and adults of T. urticae. The LT50 values for eggs, larvae, nymphs and adults were 108.52, 52.12, 75.74 and 122.43 h, respectively in Direct Spray Bioassay and 155.09, 81.55, 86.13 and 141.53 h, respectively in Treated Food Bioassay. Lower LT50 values were obtained for larvae, followed by nymphs and adults. Direct Spray Bioassay is preferred over treated Food Bioassay on the basis of lower LC50 and LT50 values for T. urticae life stages.