感染油茶象幼虫的高致病力金龟子绿僵菌菌株筛选

Screening of Metarhizium anisopliae Strain with High Virulence against Larvae of Curculio chinensis( Coleoptera: Curculionidae)

【目的】筛选对油茶象幼虫具有高致病力的绿僵菌菌株，为防治油茶象幼虫提供高效的生防菌。【方法】在测定7个金龟子绿僵菌菌株的生长速度和产孢量的基础上，采用浸渍法和孢子拌土法对油茶象幼虫进行致病力测定，并以土表喷菌液的方式进一步研究优良菌株对土壤中油茶象幼虫的感染效果。【结果】FJMa201101和FJMa201205两个菌株产孢量最高；不同绿僵菌菌株对油茶象幼虫均有一定的致病力，107孢子·mL －1的孢悬液浸渍法接种后第13天和105孢子·g －1土的孢子拌土法接种后第9天，油茶象幼虫的死亡率均达到100%，LT50分别在1.65～4.26天和1.96～3.51天之间； FJMa201101和 FJMa201205两个菌株对油茶象幼虫的致病力最强。FJMa201101菌株浸渍法接种 LT50为1.65天，感染率为86.6%；孢子拌土法 LT50为2.11天，感染率为94.5%。FJMa201205菌株浸渍法接种 LT50为1.71天，感染率为91.1%；孢子拌土法 LT50为1.96天，感染率为88.9%。林间土表喷菌液的方式，FJMa201101和FJMa201205两个菌株之间的感染效果差异不显著，但先喷菌再引入试虫较引入试虫后再喷菌的感染效果更好。【结论】FJMa201101和 FJMa201205两个金龟子绿僵菌菌株可以作为防治油茶象幼虫的优良菌株在生产上应用。

[ Objective ] Curculio chinensis （Coleoptera： Curculionidae） is one of the most serious pests of oil-tea Camellia fruits. Screening of Metarhizium anisopliae strains with high virulence against this pest is important for using fungi as biocontrol agent to suppress this pest. [ Method ] Colony growth and sporulation of 7 strains of M. anisopliae were measured and their virulence against C. chinensis larvae were investigated in laboratory by using two inoculating methods （Being dipped on larvae with conidia suspension of 107 spores-mL-I and being mixed in soil with 105 spores. g-1）. The infection effects in field were evaluated through spraying conidia suspension of two superior strains. [ Result ] Bioassay results showed that larvae of C. chinensis were susceptible to different M. anisopliae strains. The larval mortalities reached I00% on the 13th day after inoculation using dipping inoculative method and the 9th day for conidia-soil mixing inoculative method. The median lethal time （ LT50 ） of dipping inoculative method was 1.65 days to 4.26 days, and that of conidia-soil mixing inoculative method was 1.96 days to 3.51 days. The FJMa201101 and FJMa201205 strains of M. anisopliae were the most virulent against larvae of C. chinensis. When larvae inoculated with FJMa201101, the LT50 was 1.65 days, and the infection rate was 86.6% when using dipping inoculative method, while the LT50 was 2. 11 days and the infection rate was 94.5% respectively for conidia-soil mixing inoculative method. When inoculated with FJMa201205,the LT50 was 1.71 days with the infection rate of 91.1% by using dipping inoculative method . whilst it was 1.96 days with the infection rate of 88.9% with conidia-soil mixing inoculative method. In field test, there was no significant difference in infection rate between the two superior strains, but the infection rates of larvae introduced to soil after spraying conidia suspension were significantly higher than those introduced before spraying. Meanwhile, the two strains were excellent at growth performance. [ Conclusion] Therefore, the two strains of M. anisopliae, FJMa201101 and FJMa201205, could be the promising candidate in controlling C. chinensis larvae.