红火蚁活性真菌菌株的室内筛选研究

在实验室条件下采用浸渍法测定了15株白僵菌Beauveria spp.，15株绿僵菌Metarhizium spp.和4株淡紫紫孢菌Purpureocillium lilacinum (Thom)对红火蚁Solenopsis invicta Buren工蚁的活性，并测定分析了高活性菌株对红火蚁工蚁的毒力。结果表明，以1.0×10^8孢子mL的浓度处理红火蚁工蚁后第10天，白僵菌HHY-B、LCM1、ZYSYE-Y2、Bb034、ZG5、Bb720、Bb040、CP728和淡紫紫孢菌LYC1菌株的活性较强，红火蚁工蚁的校正死亡率为84.70%~98.79%，僵虫率为70.61%~90.38%。红火蚁工蚁在接种不同浓度的高活性菌株后，随着孢子浓度的升高，红火蚁的累积校正死亡率和僵虫率增大，致死中时(LT50)缩短，第10天白僵菌ZYSYE-Y2、CP728、HHY-B、LCM1、ZG5、Bb040、Bb720、Bb034和淡紫紫孢菌LCM1菌株对红火蚁工蚁的LC50分别为1.16×10^5、1.49×10^5、2.27×10^5、2.28×10^5、2.32×10^5、3.79×10^5、4.94×10^5、8.47×10^5和3.90×10^6孢子/mL。当孢子浓度为1.0×10^7孢子/mL时，白僵菌HHY-B、CP728、ZG5和Bb040菌株处理的最终校正死亡率分别为91.54%、94.60%、91.23%和94.65%，僵虫率为82.51%、91.74%、85.43%和80.60%，致死中时(LT50)为4.22 d、4.07 d、3.72 d和3.68 d。综合分析表明，白僵菌HHY-B、CP728、ZG5和Bb040菌株对红火蚁工蚁具有较强的活性，可作为红火蚁生物防治的候选菌株

Screening activity strain of entomopathogenic fungi to Solenopsis invicta in laboratory

The pathogenicity of 15 strains of Beauveria spp., 15 strains of Metarhizium spp., 4 strains of Purpureocillium lilacinum (Thom) and different concentrations of high virulence strains to Solenopsis invicta Buren was determined by the soaking method. The results showed that the Beauveria spp. HHY-B, LCM1, ZYSYE-Y2, Bb034, ZG5, Bb720, Bb040, CP728 and P. lilacinum LYC1 strains exhibited the strongest activity to red imported fire ant workers, the corrected mortality and infection rate varied from 84.70%~98.79% and 72.98%~90.38%, respectively, after inoculation with a concentration of 1.0×10^8 spores/mL for 10 d. Moreover, the corrected mortality and infection rate of S. invicta increased and the median lethal time reduced with the increase of the conidium concentration. The LC50 values of the ZYSYE-Y2, CP728, HHY-B, LCM1, ZG5, Bb040, Bb720, Bb034 and LYC1 strains on day 10 post-treatment were 1.16×10^5, 1.49×10^5, 2.27×10^5, 2.28×10^5, 2.32×10^5, 3.79×10^5, 4.94×10^5, 8.47×10^5 and 3.90×10^6 spores/mL. When inoculated with a concentraion of 1.0×10^7 spores/mL of HHY-B, CP728, ZG5 and Bb040 strains for 10 d, the corrected mortality to red imported fire ant workers were 91.54%, 94.60%, 91.23% and 94.65%, and the infection rates were 82.51%, 91.74%, 85.43% and 80.60%, the median lethal time were 4.22 d, 4.07 d, 3.72 d and 3.68 d, respectively. Collectively, the results indicated that HHY-B, CP728, ZG5 and Bb040 strains of Beauveria spp. could be good candidate strains in S. invicta biological control.