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目的:明确昆虫病原真菌绿僵菌对化橘红害虫曲牙土天牛幼虫的毒力,筛选高致病力菌株,为曲牙土天牛的生物防治提供依据。方法:先利用从化橘红基地土壤中分离及其他实验室提供的36株绿僵菌,制成孢子浓度为1×108个/g的孢子土,对曲牙土天牛1龄幼虫进行初步的毒力测定;在此基础上选取7株分离自化橘红基地土壤的绿僵菌作进一步筛选;并通过液固双相发酵法对筛选出的高毒力菌株的产孢能力进行初步评价。结果:用于作初步毒力测定的36株绿僵菌中,有28株能够侵染曲牙土天牛幼虫,其中6株僵虫率达100%,8株达80%,8株达60%,2株达40%,4株达20%;用于作进一步毒力筛选的7株菌中,有6株表现出较高的毒力,最高僵虫率均大于74%;对这6株菌的产孢量进行测定,产孢量均大于10亿个/g,其中1,4株菌产孢量显著高于其他菌株,分别为2.35±0.25(1×109个孢子/g),2.21±0.27(1×109个孢子/g)。结论:1号和4号菌株对曲牙土天牛1龄幼虫表现出了较高的毒力,并有最强的产孢能力,因此最具开发潜力。
OBJECTIVE: To clarify the virulence of Metarhizium anisopliae against the orange-red pest Calycsola larvae and screen the virulent strains for the biological control of Calyptra crassipes. Methods: 36 strains of Metarhizium anisopliae isolated from the soil of Coniferous Orange Base and spores of 1 × 108 spores / g were prepared, and the preliminary toxicity to the first instar larvae On the basis of this, 7 strains of Metarhizium anisopliae isolated from the orange-red soil base were selected for further screening. The sporulation abilities of the selected high virulent strains were evaluated by liquid-solid two-phase fermentation. Results: Of the 36 Metarhizium anisopliae strains used for preliminary virulence test, 28 strains could infect Trachissimum larvae, of which 6 were 100%, 8 were 80% and 8 were 60 %, 2 strains up to 40% and 4 strains up to 20%. Of the 7 strains used for further virulence screening, 6 strains showed higher virulence with the highest rate of over 75% The sporulation of strains was more than 1 billion / g, of which the sporulation of 1 and 4 strains was significantly higher than that of other strains (2.35 ± 0.25 (1 × 109 spores / g), respectively) 2.21 ± 0.27 (1 × 109 spores / g). Conclusions: Strain 1 and 4 showed the highest virulence to the first instar larvae and the strongest sporulation ability.