绿僵菌CQMa128乳粉剂对蛴螬时间-剂量-死亡率模型分析

用拌土法测定了金龟子绿僵菌Metarhizium anisopliae菌株CQMa128乳粉剂对蛴螬3龄幼虫的毒力。结果表明：土壤含有1×106~1×108孢子/g绿僵菌乳粉剂时,蛴螬的校正死亡率随着绿僵菌孢子浓度的增加和作用时间的延长而增大,土壤含有5×107孢子/g绿僵菌乳粉剂时蛴螬的校正死亡率达85.2%。运用时间-剂量-死亡率模型对生测数据进行拟合,通过Hos-mer-Lemeshow拟合异质性检验,并估计了该制剂对蛴螬的致死剂量与致死时间。随着接种天数的增加,相应的LD50和LD90随之降低,剂量效应逐渐增强。土壤中含有3×107、5×107和1×108孢子/g绿僵菌乳粉剂处理的LT50值分别为10.18、8.42、6.79d。当土壤含有1×108孢子/g绿僵菌乳粉剂时,蛴螬死亡率可达90%以上,LT90为10.50d。该绿僵菌制剂在蛴螬的生物防治中具较强的应用潜力。

Time-dose-mortality Model Analysis of Emulsifiable Powder Formulation of Metarhizium anisopliae CQMa128 against White Grubs

The virulence of emulsifiable powder formulation of Metarhizium anisopliae strain CQMa128 against the 3rd instar larvae of white grubs was evaluated by soil-mixing bioassay.Results showed that the corrected mortality of white grubs increased with the rise of concentration of the conidia and elongation of action time.M.anisopliae emulsifiable powder formulation showed commendable control efficiency against grubs at the concentration of 5×107 conidia per gram soil and the corrected mortality reached 85.2%.A time-dose-mortality model,conforming to Hosmer-Lemeshow goodness-of-fit test,was established to estimate the lethal dose and the lethal time of this formulation.With the extension of time,dose effect increased and LD50 and LD90 decreased.LT50 values were 10.18,8.42 and 6.79 d at concentrations of 3×107,5×107 and 1×108 conidia per gram soil,respectively.Grub mortality reached 90% and LT90 was 10.50 d when the grubs were treated with M.anisopliae emulsifiable powder formulation at the concentration of 1×108 conidia per gram soil.These results indicate that emulsifiable powder formulation of M.anisopliae CQMa128 is promising in the biological control of white grubs.