球孢白僵菌Bb84对Q型烟粉虱的时间-剂量-死亡率模型分析

为获得对Q型烟粉虱Bemisia tabaci（Gennadius）具有高毒力的杀虫真菌菌株并将其应用于生产，采用喷雾法测定了5个球孢白僵菌Beauveria bassiana菌株对烟粉虱若虫的毒力，并运用时间-剂量-死亡率模型分析了B.bassiana 84（Bb84）菌株对烟粉虱若虫的时间效应和剂量效应。结果表明:在5个供试菌株中，Bb84菌株对烟粉虱3龄若虫的致死速度快、致死率最高，逐日死亡率随着Bb84菌株孢子浓度的增加而上升，且其对2、4龄烟粉虱若虫也有较高的毒力。用时间-剂量-死亡率模型分析其剂量效应与时间效应，结果表明:随着Bb84菌株接种时间的延长，相应的致死中浓度（LC50）值随之降低，剂量效应逐渐增强；当Bb84菌株处理浓度为1.0×107、1.0×108和1.0×109孢子/mL时，其对烟粉虱3龄若虫的致死中时间（LT50）值分别为5.44、4.61和4.05 d，即LT50值随菌株孢子浓度的增加而减小，时间效应增强。因此，在实际生产中，当球孢白僵菌Bb84菌株的浓度高于1.0×108孢子/mL时，对烟粉虱3龄若虫的防治效果较好。

Time-dose-mortality of the Beauveria bassiana strain Bb84 on Q-biotype Bemisia tabaci

In order to obtain entomogenous fungi strains with high toxicity against Q-biotype Bemisia tabaci and apply it to the production, the toxicity of Beauveria bassiana strain against Q-biotype B. tabaci were measured by using the method of spray. And the time-dose-mortality (TDM) model was applied to analyze the time and dose effects of strain Bb84 on Q-biotype B. tabaci. The results showed that the mortality rate of strain Bb84 against the 3^rd nymph was the highest and its lethality was the highest among the five tested strains and the daily cumulative mortality increased with the concentrate of conidial suspension. Strain Bb84 also had high toxicity to the 2^nd and 4^th nymph. The analysis of TDM model showed that the LC 50 value decreased and dose effect increased with the extension of time; LT 50 values were 5.44, 4.61 and 4.05 d for the 3^rd nymph of B. tabaci at spore concentrations of 1.0×10⁷, 1.0×10⁸ and 1.0×10⁹ spores/mL, respectively. Thus the LT₅₀ value decreased and time effect increased with the extension of dose. Therefore, in the actual production, when the concentration of the B. bassiana strain Bb84 is higher than 1.0×10⁸ spores/mL, the control effect of the 3^rd nymph of B. tabaci is better.