From Entomopathogenic Fungi Were Identified And The Two Kinds Of Medicinal Herbs Pest Control Potential Evaluation

Citrus grandis ’Tomentosa’ and Aquilaria sinensis (Lour.) Gilg are two kinds of precious medicinal plants which are badly harmed by pests of Dorysthenes hydropicus and Heortia vitessoides respectively. With popularization of the idea to produce green herbs, more pest managing ways should be considered comprehensively besides chemical insecticide, such as improving planting and managing technology, protecting environment of herb bases, increasing the number of natural enemies. Entomopathogenic fungi are the important enemies against arthropods, showing great potential in biological control of pest. Though there are few reports about mycoinsecticide to control pests of herbs, the application of mycoinsecticides has been succeeded in some kinds of pest managements in agriculture, forestry and hygiene. In this study, two kinds of entomopathogenic fungi were isolated from two herb bases. Bioassays evaluation of35Metarhizium strains were carried out respectively against D. hydropicus and H. vitessoides, Results are as follows:1. Isolation and identification of entomopathogenic fungiEighteen entomopathogenic fungi strains were isolated from larvae of Tenebrio molitor infected in the soil samples taken from Good Agriculture Plant (GAP) base of C. grandis in Guangdong Huazhou, based on characteristics of morphological and rDNA ITS sequences, all strains were identified as Metarhizium. anisopliae var. anisopliae,12samples of Lepidoptera larva infected by entomopathogenic fungi were collected from base of Lonicer a japonica Thunb in Shandong Pingyi.12strains of fungi were isolated and identified as Nomurea rileyi based on characteristics of morphological and rDNA ITS sequences.2. Bioassay evaluation of Metarhizium against1st instar larva of D. hydropicusD. hydropicus is an important kind of pest leading to great economic loss of C. grandis. Conidia of35Metarhizium strains mixed in soil, was used to test virulence against1st instar larvae of D. hydropicus at1×108conidial/g concentration,7strains were selected for further study at1×1081×107、1×106conidial/g concentration,6strains of them showed high virulence, the highest cadaver rate reached74.3%～94.3%respectively.3Sporulations of the violent strains against D. hydropicusSix strains of fungi which showed high violence against D. hydropicus were cultivated in sabouraud dextrose yeast (SDY) medium at first, and then transfer to rice grain, conidial yields of different strains from high to low were as follows:1>4>22-3-2>31>15-2>27-2, the number of spores in every gram of dry fermentional material were2.35billion,2.21billion,1.68billion,1.57billion,1.14, billion1.08billion, conidial yields of strain1was the highest,2.2times as much as the lowest-yielding strain27-2.4Bioassay evaluation of Metarhizium against larva of H. vitessoidesH. vitessoides is one kind of defoliators to precious herb A. sinensis. Conidia suspension of35Metarhizium strains were used to test virulence against5th instar larva of H. vitessoides at first, then10strains were selected for further study at1×109、1×108、1×107conidial/ml concentration,9strains of them infected larvae into cadaver, strain10showed the highest cadaver rate at1×109conidial/ml as38%;18Metarhizium strains virulence was tested by conidia mixing in soil at1×109、1×108、1×10’conidial/g concentration,16of them could infect larvae of H. vitessoides, strain GB1-P showed the highest cadaver rate at1×109conidial/g as49%. Conidia of15strains were suspended in peanut oil, larvae of H. vitessoides were treated with conidia oil at1×1010、1×109、1×108conidial/ml, and were infected by14strains of Metarhizium, the highest cadaver was caused by strain11, cadaver rate was53%,40%,20%at concentration of1×1010、1×109、1×108conidial/ml respectively.