Pathogenicity of Beauveria bassiana strain 202 against sap-sucking insect pests

Abstract

An experimental trial was conducted to determine the pathogenicity of Beauveria bassiana strain 202 (Bb-202) against multiple targeted sucking insect species that are serious pests of crops and ornamental plants. The insect species, Myzus persicae Sulzer (Hemiptera: Aphididae), Jacobiasca formosana Paoli (Hemiptera: Cicadellidae), Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), and Stephanitis nashi (Hemiptera: Tingidae) were exposed to conidia of B. bassiana at rates of 1.0 × 10², 3.5 × 10³, 5 × 10⁴, and 6.75 × 10⁵conidia/mm² to determine the pathogenicity of B. bassiana. The fungal strain Bb-202 showed the highest pathogenicity to M. persicae and 100% corrected mortality observed in the treatments over 1.0 × 10²conidia/mm², followed by the J. formosana with the final corrected mortality of 86.6, 94.4, and 97.4% after 10 days of fungal inoculation with 3.5 × 10³, 5 × 10⁴, and 6.75 × 10⁵conidia/mm², respectively. The strain Bb-202 also showed good pathogenicity to B. tabaci and corrected mortalities of 77.9 and 81.1% were recorded when exposed to 5 × 10⁴ and 6.75 × 10⁵conidia/mm². Relatively weak pathogenicity was observed in S. nashi, in which the highest corrected mortality of 63.7% occurred at 6.75 × 10⁵conidia/mm². Accordingly, the LC₅₀and LT₅₀values of concentrations 1 × 10⁵, 1 × 10⁶, 1 × 10⁷, and 1 × 10⁸ conidia/ml were calculated for M. persicae, J. formosana, B. tabaci, and S. nashi that were determined as 6.7 × 10⁴, 1.3 × 10⁶, 3.6 × 10⁶, and 1.2 × 10⁷ conidia/ml and LT₅₀ was observed as 5.2~8.24, 5.1~6.6, 7.2~9.0, and 7.9~9.6 in days, respectively.