茶毛虫核型多角体病毒Bt混剂的作用特性

用生物测定的方法,研究了茶毛虫核型多角体病毒(EpNPV)与苏云金杆菌(Bt)配制而成的茶毛虫核型多角体病毒Bt混剂(EpNPV-Bt)的增效作用、速效作用、拒食作用和兼治作用。结果表明,在16～28℃温度范围内,EpNPV-Bt对茶毛虫的作用在整个死亡周期表现为相加作用,协同毒力指数主要分布在-20%～20%之间,其中16、19、28℃的死亡前期表现为增效作用,协同毒力指数大于20%,22℃的死亡中期表现为拮抗作用,协同毒力指数小于-20%。EpNPV-Bt对茶毛虫LT30为5.6天,比EpNPV减少3.8天,幼虫的死亡速度提高了1.8倍。EpNPV-Bt对茶毛虫的拒食效果明显,取食量比EpNPV减少66.2%。EpNPV-Bt对茶刺蛾、用克尺蠖和茶尺蠖等茶树害虫具有兼治作用,其中对茶刺蛾的死亡率达85.8%。     

腐霉利与苦参丙酮提取液对番茄灰霉病菌的联合毒力测定

采用抑制菌丝生长速率法测定了腐霉利和苦参丙酮提取物对番茄灰霉病的联合毒力。结果表明:腐霉利和苦参丙酮提取液以4种配比都对该病原菌有一定的增效作用,其中腐霉利和苦参提取液配比是0.4∶0.6时,增效为1.3,盆栽试验中的增效比为1.2,确定配比0.4∶0.6为最佳浓度比例。     

水杨酸与咪鲜胺混用对油茶炭疽病的防治效果

为明确水杨酸和咪鲜胺混用对油茶炭疽病的防治效果,采用油茶苗施药结合离体叶片接菌的方式进行了室内生物活性测定试验,并通过田间小区试验进行了防效验证。室内测定结果表明：150 mg/L水杨酸与200 mg/L咪鲜胺混用 (C2),对油茶炭疽病的相对防效显著高于200 mg/L咪鲜胺单独处理 (P2) (P < 0.05);第2次施药后10 d,混用处理C2组的增效系数达1.42,表现为增效作用;第2次药后20 d,C2处理组防治效果仍可达57.26%,而P2组仅为27.49%,表明混用可使持效期延长。田间小区试验中,C2水杨酸与咪鲜胺混用组对油茶炭疽病的田间防治效果同样显著高于P2咪鲜胺单独处理组 (P < 0.05),第2次药后28 d,C2组防效达到72.86%,P2组防效仅为46.54%。研究表明,水杨酸与咪鲜胺混用可提高咪鲜胺对油茶炭疽病的防治效果并延长其持效期,减少咪鲜胺的施药次数和使用量,达到减药增效的目的。     

Cross-Resistance to Imidacloprid in Strains of German Cockroach (Blattella germanica) and House Fly (Musca domestica)

The toxicity of a promising new insecticide, imidacloprid, was evaluated against several susceptible and resistant strains of German cockroach and house fly. Imidacloprid rapidly immobilized German cockroaches followed by a period of about 72 h during which some cockroaches recovered. After 72 h there was no further recovery. Imidacloprid-treated houseflies were immobilized more slowly than treated cockroaches, with the maximum effect observed after 72 h, and there was no recovery. Based upon 72-h LD₅₀ values imidacloprid was moderately toxic to German cockroaches (LD₅₀ values were 6–8 ng mg^-1) and had only low toxicity to house flies (LD₅₀ 140 ng mg^-1). Piperonyl butoxide (PBO) blocked the observed recovery in German cockroaches. PBO also greatly enhanced the 72-h LD₅₀ of imidacloprid from 43- to 59-fold in cockroaches and 86-fold in house flies. Two strains of German cockroach (Baygon-R and Pyr-R) showed >4-fold cross-resistance to imidacloprid. This cross-resistance could not be suppressed by PBO, suggesting that P450 monooxygenase-mediated detoxication is not responsible for this cross-resistance. Variation in the level of synergism observed with PBO (between strains) suggests the ‘basal’ level of monooxygenase-mediated detoxication of imidacloprid is quite variable between strains of German cockroach. The AVER and LPR strains of house fly showed significant cross-resistance to imidacloprid. PBO reduced the level of cross-resistance in AVER from >4·2-fold to 0·5-fold (i.e. the AVER strain LD₅₀ was half that of the susceptible strain when both were treated with PBO), but PBO did not suppress the cross-resistance in LPR. These data suggest monooxygenases are the mechanism responsible for cross-resistance to imidacloprid in AVER, but not in the LPR strain. © of SCI.     

3种喷雾助剂对螺虫乙酯和联苯菊酯防治金钗石斛菲盾蚧的增效作用

为探索添加喷雾助剂对螺虫乙酯和联苯菊酯防治石斛菲盾蚧的增效作用及机理,研究了3种喷雾助剂快速渗透剂T、有机硅助剂DA101和植物油类助剂HZS对药液物理性状的影响和添加助剂前后药剂的室内毒力和田间防效。结果表明：3种助剂均可降低22.4%螺虫乙酯悬浮剂和100 g/L联苯菊酯乳油药液的表面张力和叶面接触角,并增加了药液在金钗石斛叶片的最大持留量;添加3种喷雾助剂均提升了螺虫乙酯和联苯菊酯对石斛菲盾蚧若虫的室内毒力,其中快速渗透剂T对螺虫乙酯、植物油类助剂HZS对联苯菊酯的增效作用最强,增效比分别达34.4%和24.3%;田间防效表明添加快速渗透剂T对螺虫乙酯、添加植物油类助剂HZS对联苯菊酯防治石斛菲盾蚧均有较好的增效作用,快速渗透剂T对螺虫乙酯的防效提高了8.2%~22.8%,植物油类助剂HZS对联苯菊酯的防效提高了10.6%~27.5%。综上,添加喷雾助剂对药剂防治石斛菲盾蚧具有明显的增效作用,生产实践中适宜推广应用。