Abstract:

 Planococcus lilacinus and Phenacoccus solani were two newly recorded quarantine pest inChina. These two pests have been posing a serious damage in sugar apple orchards and succulent plants inFujianprovince. In this study, we assayed the biological characteristics, pathogenicity and extracellular enzyme activity of Beauveria bassiana BB-T02 against P. lilacinus and P. solani, so as to evaluate the biocontrol potential of strain BB-T02 against these two quarantine mealybugs. Results showed that the optimal culture conditions for strain BB-T02 growth and sporulation were 28 ℃, photoperiod 8L:16D, with maltose as carbon source and peptone as nitrogen source. With these conditions, the colony diameter and sporulation of strain BB-T02 were5.60 cmand 4.22×10⁸ conidia/cm² after ten days cultivation, respectively. Infected P. lilacinus and P. solani ten days, the LC₅₀ values of the strain BB-T02 were 5.00×10⁵ conidia/mL and 2. 17×10⁵ conidia/mL, the lethalities were 85.39% and 88.76%, and the LT₅₀ values were 5.78 d and 5.19 d for the 1×10⁸ conidia/mL treatment, respectively. The change amplitude in protease activity of strain BB-T02 was obvious, with peak values of 22.68 U/mL on fifth day. The change amplitude in activities of chitinase and lipase were relatively stable, with peak values of 13.19 U/mL and 9.77 U/mL on sixth day, respectively. In conclusion, with fast growth, high sporulation, and strong infection activity against P. lilacinus and P. solani, Beauveria bassiana BB-T02 shows an excellent potential in biological control of these two quarantine mealybugs.

Key words:

Beauveria bassiana, biological characteristics, Planococcus lilacinus, Phenacoccus solani, infection activity