Pathogenicity assessment of an indigenous strain of Trichoderma harzianum Rifai (Ascomycota: Hypocreales) to the grasshopper, Chrotogonus trachypterus (Orth.: Pyrgomorphidae) (B.) in laboratory conditions

The Sugarcane grasshopper (Chrotogonus trachypterus) is one of the most important and indigenous and harmful pest of field crops in Sistan region of Iran and cause considerable damage especially during seedling stages. We conducted this study in order to introduction of a biocontrol agent to C. trachypterus in a completely randomized designs and factorial experiment with three replications using topical application under laboratory conditions. For inoculations, after the preliminary experiments, five fungal suspensions prepared at consecrations of 1×104, 1×105, 1×106, 1×107 and 1×108 conidia mL-1 in distilled water containing 0.05% Tween-80®. Grasshoppers typically inoculated under the pronotal shield using a Hamilton microaplicator. Control treatment were treated with distilled water containing 0.05% Tween-80® as surfactant. The corrected cumulative percent mortality was recorded daily until 15 days after inoculations. Percentage of insect mortality was analyzed using (log-probit) methods. Results showed T. harzianum was pathogenic to adult insects and insect mortality increased with increasing concentrations. The highest and lowest mortality observed at 108 conidia mL-1 and 104 conidia mL-1 with a 75 and 25 percent respectively (p50 value was 1.01×106 conidia mL-1. This is the first report of the pathogenicity of T. harzianum to the grasshopper, C. trachypterus.