光照和漂白粉对白僵菌孢子萌发及致病力的影响

Effect of Light Irradiation and Bleaching Powder on Spores Germination and Pathogenicity of Beauveria bassiana

研究人工紫外光和自然光照射以及消毒剂漂白粉对白僵菌(Beauveria bassiana)孢子萌发和致病力的影响。结果表明,人工紫外光照射对裸露的白僵菌孢子有明显的杀伤作用,使孢子萌发率和对家蚕(Bombyx mori L.)的致病力明显下降,但对白僵菌原粉中的孢子杀伤力相对较弱,照射24 h后白僵菌原粉对家蚕的致死率仍达93.33%。在自然光下,喷洒到桑叶上的白僵菌孢子悬浮液随光照时间的增加对家蚕的致病力下降,自然光照射3、6、12、24、36 h后,对家蚕的致死率分别为100.00%、70.00%、79.66%、10.00%和25.00%;用白僵菌原粉喷桑树,经自然光照射0～36 h后,对家蚕的致死率为88.33%～96.67%,48 h后对家蚕的致死率大幅度下降,照射48、54、78 h对家蚕的致死率分别为53.33%、31.67%和23.33%;直接置于自然光下照射的白僵菌原粉,随光照时间增加,对家蚕的致病力下降,30 h后致病力明显下降,致死率只有38.33%。有效氯浓度为1.00%和2.00%的漂白粉溶液对白僵菌孢子萌发有很强的抑制作用,72 h孢子萌发率分别为1.000%和0;用有效氯浓度为2.00%的漂白粉液进行叶片和蚕体消毒处理对白僵菌孢子均有杀灭效果,使白僵菌孢子液和原粉对家蚕的致病力明显下降,但对叶片消毒比对蚕体消毒效果好。

The effect of light irradiation and bleaching powder on spores germination and pathogenicity of Beauveria bassiana was studied.The results showed that ultraviolet ray had obvious damaging effect on isolated spores of B.bassiana and markedly reduced spores germination rate and its pathogenicity to silkworm;but the damaging power of ultraviolet ray to spores in pesticide powder was relatively weak as the pathogenicity to silkworm was still 93.33% after 24 h irradiation.Irradiation of outside natural light also decreased the pathogenicity of B.bassiana to silkworm,the longer the irradiation,the lower the pathogenicity.The mortality of silkworm fed with mulberry leaves sprayed with spores suspension was 100.00%,70.00%,79.66%,10.00% and 25.00% respectively under outside natural light irradiation of 3,6,12,24 and 36 h.The mortality of silkworm fed with mulberry leaves sprayed with pesticide powder was 88.33%～96.67% under outside natural light irradiation for 0～36 h,and 53.33%,31.67% and 23.33% respectively under outside natural light irradiation for 48,54,and 78 h.The mortality of silkworm directly sprayed with pesticide powder irradiated by outside natural light was reduced with the increase of irradiation time,the mortality of silkworm was merely 38.33% under 30 h of irradiation.Bleaching powder solution with 1.00% or 2.00% available chlorine exhibited strong inhibition on spores germination of B.bassiana.The pathogenicity of spores suspension and pesticide powder to silkworm was evidently decreased by treating leaves and body of silkworm with bleaching powder solution of 2.00% available chlorine;and the effect of treating leaves was better than treating body of silkworm.