棕色绿僵菌最适培养基和杀蝇蛆分生孢子浓度探究

Study on the optimum medium and concentration of fly maggot-killing conidia of Metarhizium brunneum

为了研究昆虫寄生性真菌—棕色绿僵菌(Metarhizium brunneum)的最适培养基和杀蝇蛆分生孢子浓度,试验对棕色绿僵菌在不同固体培养基、液体培养基、氯化钠浓度和pH值条件下的生长特征和产孢能力进行了测定,并分别统计不同浓度(1×10^(4)个/mL、1×10^(5)个/mL、1×10^(6)个/mL、1×10^(7)个/mL和1×10^(8)个/mL)分生孢子悬液处理后第3,5,7天的蝇蛆累计死亡率。结果表明:棕色绿僵菌在马铃薯葡萄糖琼脂培养基上培养第21天时的菌落直径最大(8.40 cm),然后从大到小依次为PPDA固体培养基(8.20 cm)、沙氏葡萄糖琼脂培养基(8.10 cm)、枸橼酸固体培养基(7.20 cm)、大豆蛋白胨固体培养基(4.90 cm)、玉米粉琼脂培养基(4.70 cm);在马铃薯葡萄糖琼脂培养基上培养第21天时的分生孢子产量最高(4.830×10^(7)个/mL),然后从高到低依次为PPDA固体培养基(3.070×10^(7)个/mL)、沙氏葡萄糖琼脂培养基(1.770×10^(7)个/mL)、枸橼酸固体培养基(1.580×10^(7)个/mL)、大豆蛋白胨固体培养基(0.260×10^(7)个/mL)、玉米粉琼脂培养基(0.053×10^(7)个/mL);在萨氏液体培养基中培养第7天时的菌丝干重最高(10.6 mg/mL),然后从高到低依次为马铃薯液体培养基(8.0 mg/mL)、沙氏葡萄糖液体培养基(7.1 mg/mL)、玉米浸液液体培养基(0.2 mg/mL);在萨氏液体培养基中培养第7天时的分生孢子产量最高(5.29×10^(7)个/mL),然后从高到低依次为马铃薯液体培养基(2.86×10^(7)个/mL)、沙氏葡萄糖液体培养基(2.71×10^(7)个/mL)、玉米浸液液体培养基(1.53×10^(7)个/mL)。棕色绿僵菌在氯化钠浓度为0.15 mol/L或pH值为8的马铃薯葡萄糖琼脂培养基上培养第21天时的菌落直径最大,分生孢子产量最高。用棕色绿僵菌分生孢子悬液(浓度分别为1×10^(4)个/mL、1×10^(5)个/mL、1×10^(6)个/mL、1×10^(7)个/mL和1×10^(8)个/mL)处理第3天,家蝇三期幼虫的累计死亡率为13.3%~40.0%;处理第5天,家蝇三期幼虫的累计死亡率为26.7%~66.7%;处理第7天,家蝇三期幼虫的累计死亡率为40.0%~90.0%。浓度为1×10^(6)个/mL、1×10^(7)个/mL和1×10^(8)个/mL的分生孢子悬液处理第7天时家蝇三期幼虫的累计死亡率显著高于浓度为1×10^(4)个/mL、1×10^(5)个/mL的分生孢子悬液(P<0.05),且浓度为1×10^(6)个/mL、1×10^(7)个/mL和1×10^(8)个/mL的分生孢子悬液处理第7天时家蝇三期幼虫的累计死亡率之间差异不显著(P>0.05)。说明棕色绿僵菌的最适培养基为马铃薯葡萄糖琼脂培养基和萨氏液体培养基,培养基最适氯化钠浓度为0.15 mol/L、pH值为8;棕色绿僵菌分生孢子悬液对蝇蛆有较强的侵染杀灭作用,推荐的杀蝇蛆浓度为1×10^(6)个/mL。

In order to study the optimum medium of entomogenous fungi Metarhizium brunneum and the concentration of fly maggot-killing conidia,in the experiment,The growth characteristics and spore-producing ability of Metarhizium brunneum were measured under different solid medium,liquid medium,sodium chloride concentration and pH value;and the cumulative mortality of maggots on the third day,the fifth day,the seventh day after treatment of conidial suspensions with different concentrations(1×10^(4)/mL,1×10^(5)/mL,1×10^(6)/mL,1×10^(7)/mL and 1×10^(8)/mL)were calculated,respectively.The results showed that the maximum colony diameter(8.40 cm)of Metarhizium brunneum was cultivated on potato glucose agar medium on the 21st day,and then from large to small were PPDA solid medium(8.20 cm),Sachseria glucose agar medium(8.10 cm),citrate solid medium(7.20 cm),soy peptone solid medium(4.90 cm),and cornmal agar medium(4.70 cm).The highest yield of conidia(4.830×10^(7)cells/mL)was cultured on potato glucose agar medium on the 21st day,and then from high to low were PPDA solid medium(3.070×10^(7)cells/mL),Sachseria glucose agar medium(1.770×10^(7)cells/mL),citrate solid medium(1.580x 107 cells/mL),soybean peptone solid medium(0.260×10^(7)cells/mL),and cornmal agar medium(0.053×10^(7)cells/mL).The highest dry weight of mycelium(10.6 mg/mL)was cultured in Sarge's liquid medium on the 7th day,and then from high to low were potato liquid medium(8.0 mg/mL),Sabouraud's glucose liquid medium(7.1 mg/mL),and corn infusion liquid medium(0.2 mg/mL).The highest yield of conidia(5.29×10^(7)cells/mL)was cultivated in Sarge's liquid medium on the 7th day,and then from high to low were potato liquid medium(2.86×10^(7)cells/mL),Sabouraud's glucose liquid medium(2.71×10^(7)cells/mL),and corn infusion liquid medium(1.53×10^(7)cells/mL).When the concentration of sodium chloride in potato glucose agar medium was 0.15 mol/L or pH value was 8,the colony diameter and conidium yield of Metarhizium brunneum on the 21st day of culture were the highest.On the 3rd day of treatment,the cumulative mortality of Musca domestica larvae of stageⅢwas 13.3%-40.0%of Metarhizium brunneum conidium suspensions(concentrations of 1×10^(4)/mL,1×10^(5)/mL,1×10^(6)/mL,1×10^(7)/mL and 1×10^(8)/mL,respectively).On the 5th day of treatment,the cumulative mortality rate was 26.7%-66.7%.On the 7th day of treatment,the cumulative mortality of Musca domestica larvae of stageⅢwas 40.0%~90.0%.On the 7th day of treatment with 1×10^(6)/mL,1×10^(7)/mL and 1×10^(8)/mL conidial suspensions,the cumulative mortality of Musca domestica larvae of stageⅢwas significantly higher than that with 1×10^(4)/mL and 1×10^(5)/mL conidial suspensions(P<0.05).There was no significant difference in the cumulative mortality of Musca domestica larvae of stageⅢon the 7th day of treatment with concentrations of 1×10^(6)/mL,1×10^(7)/mL and 1×10^(8)/mL conidia suspensions(P>0.05).The results suggested that the optimal medium for Metarhizium brunneum was potato glucose agar medium and Sarge's liquid medium with sodium chloride concentration of 0.15 mol/L and pH 8,and the recommended concentration of fly maggot-killing conidia was 1×10^(6)cells/mL.