SCREENING THE VIRULENCE OF METARHIZIUM ANISOPLIAE MT193505 AGAINST THE SPIDER MITE, TETRANYCHUS URTICAE KOCH

Tetranychus urticae Koch has been known as one of the most harmful pests of agricultural crops, controlling of which using synthetic acaricides is probably prone to different problems. Therefore, non- chemical measure are being developed as alternative option, avoiding those drawbacks. The present study aims at investigating the potential of the entomopathogenic fungus, Metarhizium anisopliae to control spider mite, T. urticae Koch. Data illustrate that all fungal isolates were pathogenic to spider mite, causing mortality of about 85.71% against T. urticae associated with LT50values ranging from 3.12 and 6.52 days for 2.4 x107 and 2.4 x109 spore /ml, of M. anisopliae, respectively. Concerning the factors affecting the activity of enzymes excreted by fungus, the optimum temperature was 30oC and pH value was 6.0 for lipase and chitinase. The optimal incubation period was 5 and 7 days for lipase and chitinase, respectively. Chitinase gene on the fungus M. anisopliae was determined by PCR amplification achieve at annealing of 55oC and appeared in a 900 bp fragment at gel marker. The adult mites of T. urticae treated by M. anisopliae culture were inspected by SEM that demonstrated the existence of colonies of M. anisopliae on the body surface of T. urticae, that could be recognize by many conidia.