Virulence of an indigenous strain of Trichoderma harzianum Rifai (Ascomycota: Hypocreales) to the grasshopper, Chrotogonus trachypterus (Orth.: Pyrgomorphidae) Blanchard in laboratory conditions
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The Sugarcane grasshopper (Chrotogonus trachypterus) is one of the most important, indigenous and harmful pests of field crops in Sistan region of Iran and causes considerable damage especially during seedling stages. This study was conducted to introduce a biocontrol agent for Ch. 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 pro-notal shield using a Hamilton microaplicator. Control insects 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) method. 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 (p<0.05). The LC50 value was 1.01×106 conidia mL-1. This is the first report of the pathogenicity of T. harzianum to the grasshopper, Ch. trachypterus.
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