Identification of 29 strains of entomogenous fungi and their toxicity to Bemisia tabaci

Objective  To identify 29 strains of entomogenous fungi and select high virulent strains against Bemisia tabaci.

Method  Identification of fungi were based on morphological analysis and genetic homology analysis of sequences in ITS, TEF and Bloc regions. The fungal toxicity to B. tabaci was evaluated by the immersion method.

Result  Twenty-six of 29 entomogenous fungal strains had the characteristics of Beauveria and the other three strains of SB003, SP665 and SP670 were identified as Isaria. Phylogenetic tree was constructed using TEF region sequence, Bloc region sequence and TEF-Bloc combined sequence, which showed that 29 strains included 24 strains of Beauveria bassiana, 2 strains of B. pseudobassiana, and 3 strains of Isaria cateinannulata. The mortality of the 2nd instar nymph of B. tabaci increased with the increase of spore concentration, and the pathogenicity of different strain was different. The 2nd instar nymphs of B. tabaci were treated with 1×10⁸ mL⁻¹ spore suspension for 7 days, and the SP433 strain had the highest lethality rate of 87.37%, followed by SB009 with a lethality rate of 82.93%.

Conclusion  This study can provide a theoretical basis for the classification of entomophytic fungi. The highly pathogenic strains of SP433 and SB009 were screened out, which can provide a reference for the biological control of B. tabaci.