玫烟色棒束孢对烟粉虱致病的时间-剂量-死亡率模型分析

Time-dose-mortality Model of Isaria fumosorosea against Bemisia tabaci( Homoptera: Aleyrodidae)

为了寻找烟粉虱生物防治的新途径,用浸叶法测定了生防菌玫烟色棒束孢IF-1106菌株对烟粉虱各虫态的致病力。结果表明,接种该菌株孢子悬浮液后烟粉虱各虫态均可被感染而发病死亡。在供试浓度(1.0×107、5.0×106、1.0×106、5.0×105、1.0×105cfu/m L)处理下,烟粉虱各虫态的累计校正死亡率均随着孢子悬浮液浓度的增加和时间的延长而升高。2龄若虫的累计校正死亡率最高,在浓度为1.0×107cfu/m L的孢子悬浮液处理7 d后达到83.05%。运用时间-剂量-死亡率模型对生物测定数据进行拟合,并估计了该菌株对烟粉虱的致死剂量与致死时间。随着接种天数的增加,烟粉虱各虫态的致死中浓度(LD50)和死亡率为90%所对应的浓度(LD90)降低,生防菌的剂量效应逐渐增强,2龄若虫在接种后7 d的LD50对数剂量估计值为4.37。生防菌的致死时间与剂量呈负相关,在1.0×105~1.0×107cfu/m L内随生防菌浓度的增加2龄若虫的致死中时(LT50)由5.66 d降到4.47 d。玫烟色棒束孢IF-1106菌株对烟粉虱2龄若虫有较高的致病效果,是烟粉虱生物防治的潜力菌株。

In order to effectively control Bemisia tabaci, the virulence of Isaria fumosorosea IF-1106 isolate against different instars of B. tabaci was evaluated by immersing leaves. Results showed that all states of B. tabaci could die after infection of I. fumosorosea. Under the treatment of I. fumosorosea conidial suspension with the concentration of 1.0×10^7,5.0×10^6,1.0×10^6,5.0×10^5,1.0×10^5cfu /m L , the accumulative adjusted mortality of B. tabaci increased with rise of concentration of the conidia and elongation of action time. The accumulative adjusted mortality of 2nd instar larvae was the highest among all instars, which reached 83.05% after 7 days of treatment by 1.0 ×10^ 7 cfu/mL. A time-dose-mortality model conforming to Hosmer-Lemeshow goodness-of-fit test was established to estimate the lethal dose and lethal time of Isaria fumosorosea IF-1106 against B. tabaci. With the extension of time , the dose effect increased, LD50 and LD90 decreased. The estimated LD50 logarithm of 2^nd instar larvae on the 7th day after treatment was 4. 37. The time effect was negatively correlated to the dose,and the LT50 values of 2^nd instar larvae decreased from 5.66 d to 4.47 d with the increase of the concentration in the range of 1 .0×10^ - 1.0 ×10^7 cfu/mL. I. famosorosea IF-1106 has high pathogenicity to the 2 ^nd instar larv ae, and is promising in the biological control of B. tabaci.