| Abstrakt: |
Background: In this study, an entomogenous, fungus was isolated from the Egyptian mealybug, Icerya aegyptiaca(J.) (Hemiptera: Monophlebidae) on the parasol leaf tree, Macaranga tanarius, in China where evaluated as a biocontrol fungus to reduce the population of the target insect. The strain was identified as Aspergillus parasiticusby morphological and phylogenetic analysisand named ZHKUAP1. The biological characteristics, pathogenicity, and field control effect of the strain were determined. Results: The most suitable medium for the mycelial growth of strain ZHKUAP1 was PPDA medium, with an optimum temperature of 30 °C and pH 7, in addition to glucose and peptone as carbon and nitrogen sources. The optimum sporulation conditions were the PPDA medium at 30 °C and pH 6, using the soluble starch and beef extract as carbon and nitrogen sources. The mycelial growth and spore production of strain ZHKUAP1 were stopped at 70 °C and above, indicating that it was not resistant to high temperatures. High concentrations of spore suspension, against young insect age, resulted high corrected mortality, as well as decreased the median lethal time. When the spore concentration was 1 × 108cfu/ml, the corrected mortality of the second nymph was 88.33%, and the LT50was 0.66 day. After 10 days of inoculation, the LC50of the second instar nymph was the smallest, reaching 4.07 × 104cfu/ml. On the 10th day of the field experiment, the corrected mortality was 76.45%, indicating that the A. parasiticusstrain ZHKUAP1 had strong pathogenicity on I. aegyptiacapopulation. Conclusions: The indoor toxicity of the strain to I. aegyptiacawas determined, and the field control effect of the pathogen was explored on this basis. The results have important application prospects in the biological control of I. aegyptiaca. |
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