球孢白僵菌分生孢子乳悬剂对甘蓝上桃蚜的田间控制效果

利用液-酵法生产球孢白僵菌(Beauveria bassiana)SG8702菌株的分生孢子粉，配制成含孢量为10^10个.ml^-1的孢子乳悬剂Ⅰ，在此基础上按1％(W／V)的比例舔加10％砒虫琳可湿性扮剂而得孢子乳悬剂Ⅱ．于2001年7月对两种孢子乳悬剂在云南昆明进行了自然条件下甘蓝上桃蚜(Myzus persicae)的田间小区(5．5m×4．8m)药效试验，各3个浓度(含孢量分别为10^7、10^6及10^5个·ml^-1常规喷雾处理，重复设清水喷雾对照，重复3次，随机区组排列．在喷菌后连续28d的田间蚜虫密度定期抽样调查中，乳悬剂Ⅱ的1000倍稀释液喷雾有效抑制了蚜虫数量增长,喷后策7—28天防效始终在90％以上．乳悬剂Ⅰ的相同稀释液喷雾对桃蚜的控制略逊于乳悬剂Ⅱ，但喷后第7天的相对防效也达到85％，此后维持防效70％以上达两周，策24天和28天才分别降至64．4％和52．6％．用含孢量10^6和10^5个·ml^-1的菌液喷雾，乳悬剂Ⅰ仍表现出明显的控蚜效果，而舔加微量砒虫琳的乳悬剂Ⅱ的控蚜效果总是优于同一浓度下的乳悬剂Ⅰ，昆明地区夏季温和而多小雨的气候有利于孢子乳悬剂发挥作用．

Field efficacy of emulsifiable suspensions of Beauveria bassiana conidia for control of Myzus persicae population on cabbage

The conidial powder of Beauveria bassiana SG8702 produced using a diphasic fermentation technology was formulated into emulsifiable suspension I (EI-I, > 10(10) conidia.ml-1) and ES-II, which resulted from adding 1% (W/V) of imidacloprid 10% WP to the ES-I. Three dilutions (10(7), 10(6), and 10(5) conidia.ml-1 of each were sprayed onto cabbage plants for control of the green peach aphid Myzus persicae population in field plots in Kunming, Yunnan during July 2001. Each dilution and a water spray as control were replicated three times. During a 28 d period of sampling at 3 or 4 d intervals, spray of the ES-II at 10(7) conidia.ml-1 controlled the increase of the aphid population by > 90% consistently from day 7 after spray. The efficacy for the ES-I at the same concentration reached 85% on day 7 after spray, exceeded 70% in the following two weeks, but declined to 64.4% on day 24 and 52.6% on day 28. At the lower concentrations sprayed, both suspensions significantly suppressed the increase of M. persicae population, but the ES-II resulted in higher efficacy than the ES-I. Local summer weather with mild temperature and frequent rainy days was favorable to the use of the formulations for aphid control.