Evaluation of entomopathogenic fungi against the sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae)


Abstract: The sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae), is one of the most destructive pests of plane trees (Platanus spp.) worldwide. This pest is a major nuisance in Europe since plane trees are very popular in parks. Thirteen entomopathogenic fungal strains including 4 isolates of Beauveria bassiana, 2 isolates of Beauveria pseudobassiana, 6 isolates of Metarhizium anisopliae, and 1 isolate of Isaria fumosorosea were screened against adults and nymphs of C. ciliata under controlled laboratory conditions in order to test their efficacy and search for an effective and safe biocontrol agent strategy. Each isolate was applied with a conidial concentration of 1 × 10^7 conidia mL^{-1} to adults and nymphs of the pest. B. bassiana isolate KTU - 24 showed the highest mortality for both adults and nymphs with 86% within 2 weeks after inoculation. This isolate also caused the highest mycosis for adults and nymphs with 83% and 80%, respectively. Mortalities of the other fungal isolates ranged from 43% to 86% and from 36% to 73% for adults and nymphs. Therefore, B. bassiana KTU - 24 was selected for further dose mortality tests based on its high virulence and mycosis value. Dose-response mortality bioassays using 5 different concentrations (1 × 10^4, 1 × 10^5, 1 × 10^6, 1 × 10^7, and 1 × 10^8 conidia mL^{-1}) were performed to determine the lethal concentration (LC_{50}) of this isolate. Based on probit analysis, the LC_{50} values of isolate B. bassiana KTU - 24 were calculated as 5.51 × 10^5 and 3.96 × 10^5 conidia mL^{-1} against adults and nymphs, respectively. Consequently, B. bassiana KTU - 24 appears to be a promising candidate for further investigations as a biocontrol agent against C. ciliata.

Keywords: Sycamore lace bug, Beauveria bassiana, bioassay, virulence, microbial control

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