Comparative analysis of blastospore production and virulence of Beauveria bassiana and Cordyceps fumosorosea against soybean pests

摘要

Blastospores are yeast-like infective cells to arthropod pests and can be obtained shortly by liquid culture. However, fungal isolates exhibit striking variation in production, desiccation tolerance and virulence. In this study, we screened three isolates of Beauveria bassiana (Balsamo) Vuillemin and three of Cordyceps fumosorosea (Wize) (Hypocreales: Cordycipitaceae) for blastospore production and assessed desiccation tolerance by air drying. The virulence of these isolates were determined against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, Spodoptera frugiperda (J.E. Smith) and Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae). The isolates ESALQ-1296 and ESALQ-3422 of C. fumosorosea and ESALQ-4958 of B. bassiana yielded blastospore concentrations above 1 x 10(9) ml(-1), but only the two C. fumosorosea isolates retained viability rates above 75% after drying. Blastospores of both fungal species were more effective in killing the three insect species than aerial conidia. In summary, blastospores of C. fumosorosea ESALQ-1296 hold the best promise for broad-spectrum pest control in soybean.