对黄曲条跳甲高毒力Bt菌株的鉴定及田间药效评价

Identification and Field Control Efficiency of High Virulence Bt Strain against Phyllotreta striolata

为了探索蔬菜害虫黄曲条跳甲的生物防治措施,从海南省土壤中分离出的一株对黄曲条跳甲高毒力Bt菌株BS128,根据形态学和分子水平鉴定,明确该菌株属于苏云金芽胞杆菌,含有cry8Ga新型杀虫编码基因。通过室内生物活性评价,苏云金芽胞杆菌BS128菌悬液对黄曲条跳甲3 d的LC50值为60.0093μg/mL,250μg/mL BS128菌悬液9000 mL/hm^(2)土壤处理对黄曲条跳甲防治效果为67.66%(15 d),250μg/mL BS128菌悬液9000 m L/hm^(2)叶面喷雾对黄曲条跳甲7 d和10 d防效分别为61.86%和62.16%。结果显示2株Bt菌株土壤处理防治跳甲效果不低于叶面喷雾防治效果。我们认为利用Bt防治黄曲条跳甲更适用土壤处理,一方面重视了土壤中黄曲条跳甲幼虫的防治,可以减缓苗期成虫的危害;另一方面Bt在土壤中更利于发挥作用,持效期长,避免了叶面喷施Bt受到高温或者强紫外线照射失活。

Biological control of Phyllotreta striolata was explored by isolating and screening highly virulent Bt strains.A strain was isolated from the soil of Hainan Province,which was identified using morphological and molecular methods as a Bacillus thuringiensis strain and named as BS128,and the strain contained a novel insecticidal coding gene Cry8Ga.Laboratory assay of the strain showed a 3-d LC50 of 60.0093μg/mL against P.striolata.Field tests showed a control efficiency of 67.66%against P.striolata at 15 d post-treatment using 250μg/mL BS128 suspension 9000 mL/hm^(2) as soil treatment and control efficacies of 61.86%and 62.16%against P.striolata at 7 d and 10 d post-treatment using 250μg/mL BS128 suspension 9000 mL/hm^(2) as foliar spray,respectively.The results indicate that soil treatment using the strain achieved equal control of P.striolata to that of foliar spray.We believe that soil treatment using the strain is more suitable for control of P.striolata,because the soil treatment using the strain against P.striolata larvae in the soil can lessen the damage of adult beetles in the seedling stage and,Bt is more effective in the soil and has a longer persistence,which avoids the inactivation of foliar sprayed Bt by high temperature or strong UV radiation.