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在室内筛选了对红火蚁Solenopsis invicta敏感的4株球孢白僵菌Beauveria bassiana菌株,分别为Bb1501,5974,pr1-6和prl::chi,通过生物测定研究了它们对红火蚁的毒力。实验采用喷雾法并在25±1℃和12L:12D条件下饲养观察10d。实验结果表明,所选的4株白僵菌对红火蚁都有较强的毒力,红火蚁的死亡率随着所用白僵菌浓度的加大而升高。所得实验数据输入时间-剂量-死亡率模型,模拟的模型均可通过Hosmer-Lemeshow拟合异质性检验,表明模型拟合良好。由模型得到各个菌株的时间效应和浓度效应互相相关,即菌株浓度越高,所用的杀虫时间就越短;而随时间的延长,所需要的致死中浓度(LC50)就越来越低。取模型输出的第10d的LC50值,将所选4株白僵菌的毒力由强到弱排序,依次为:pr1-6、pr1::chi、5974和Bb1501。它们的LC50分别为:3.16×105、8.01×105、2.4×106和1.57×107孢子/mL。这4株菌在红火蚁的生物防治中具有一定的潜力。其中,菌株5974的致死速度最快,综合考虑时间效应和浓度效应,该菌株值得进一步研究和开发为生物农药并用于红火蚁的防治。
Four strains of Beauveria bassiana from the Solenopsis invicta were screened indoors and identified as Bb1501, 5974, pr1-6 and prl :: chi, respectively. Their bioassays were used to study their virulence against T. fire ant. The experiment was carried out by spraying and keeping at 25 ± 1 ℃ and 12L: 12D for 10 days. The results showed that the four selected strains of Beauveria bassiana all had strong virulence against T. ants, and the mortality of S. invicta increased with the concentration of Beauveria bassiana. The experimental data were entered into the time-dose-mortality model and the model was fitted by the Hosmer-Lemeshow fitting heterogeneity test, which showed that the model fit well. The time effect and the concentration effect of each strain obtained by the model are related to each other, that is, the higher the concentration of the strain, the shorter the insecticidal time used; and the lower the required lethal concentration (LC50) with time. Taking the LC50 value of the 10th day of the model output, the virulence of the 4 strains of Beauveria bassiana was sorted from strong to weak, followed by pr1-6, pr1 :: chi, 5974 and Bb1501. Their LC50 were: 3.16x105, 8.01x105, 2.4x106 and 1.57x107 spores / mL, respectively. These four strains have certain potential in the biological control of red imported fire ant. Among them, the lethal strain of strain 5974 was the fastest. Considering the time effect and concentration effect, this strain deserved further research and development as a bio-pesticide for the prevention and treatment of RIFA.