In vitro Isolation and Identification of Metarhizium pinghaense Isolates and Assessment of Their Virulence against Whiteflies and Aphids

Four entomopathogenic fungal isolates were obtained from soil samples collected in Shouguang City, Shandong Province, using yellow mealworms as the baits. The result derived from the morphological and molecular identification of and assessment of the virulence against whiteflies ( Bemisia tabaci ) and the 4th instar aphids ( Aphis gossypii ) confirmed all four isolates as Metarhizium pinghaense , named SG-A, SG-B, SG-C, and SG-D, respectively. they were able to infect B. tabaci and A. gossypii with some differences in virulence and parasitic duration. The cumulative corrected mortality rates of B. tabaci and A. gossypii treated with the SG-A spore suspension (1×10 ⁸ conidia/ml.) were 94.44% and 96.67%, respectively in 8 days after inoculation. The LC ₅₀ and LT ₅₀ of SG-A against B. tabaci and A. gossypii were 7.00×10 ⁴ , 4.21×10 ⁵ (conidia/ml), 4.13 and 2.61 (days) respectively. Moreover, SG-C was more pathogenic to B. tabaci than to A. gossypii , but SG-B and SG-D were less virulent to both insects. In conclusion, M. pinghaense SG-A is highly pathogenic and greatly lethal against both A. gossypii and B. tabaci and should be used as a potential biocontrol agent to control whiteflies and aphids at their nymph stage during the vegetable production season.