2014年云南番茄、辣椒上番茄斑萎病毒属病毒与传毒蓟马的发生特点

通过对大田栽培的烟草及周边杂草释放捕食螨——巴氏新小绥螨(Neoseiulus barkeri)，探究对西花蓟马(Frankliniella occidentalis)具有最佳防治效果的捕食螨施用方法。

烟草大田期分别施用1~3次巴氏新小绥螨，每次释放间隔15 d，每种释放次数下分别设置在烟草和杂草上同时释放、仅在烟草上释放以及仅在杂草上释放3种方式。通过对比分析巴氏新小绥螨不同释放次数和不同释放方式下西花蓟马的种群数量，评价巴氏新小绥螨对烟草上西花蓟马的防控效果。

不同方式释放巴氏新小绥螨均能不同程度降低烟草大田期西花蓟马的种群数量。在烟草和杂草上同时施用3次巴氏新小绥螨对西花蓟马种群数量的控制效果最好，且维持时间最长，最高相对防效为58.02%；施用2次的防治效果次之，最高相对防效为55.57%；而仅施用1次巴氏新小绥螨对西花蓟马的防治效果最差且维持时间最短，最高相对防效仅为49.96%。相同施用次数下，仅在烟草上施用巴氏新小绥螨对西花蓟马的防治效果略高于仅在杂草上施用，但两者无显著差异。

在烟草和烟田杂草上同时释放巴氏新小绥螨能较好地控制西花蓟马，且在烟草大田期至少同时在烟草和杂草上释放2次巴氏新小绥螨(间隔期约为15 d)才能达到相对较好的防治效果。在成本允许的情况下，巴氏新小绥螨释放次数越多，对西花蓟马的防控效果越好。

Characterization and epidemiology of outbreaks of Impatiens necrotic spot virus on lettuce in coastal California

To explore the predatory mite release way with the best control effect on Frankliniella occidentalis through spraying Neoseiulus barkeri on tobacco plants and/or weeds with different times in the field. N. barkeri was sprayed one to three times with 15-day intervals, respectively, during tobacco growing season in the field. Three N. barkeri release ways including application N. barkeri on both tobacco and weeds, only on tobacco or weeds were set respectively under each release time. The control effect of N. barkeri on F. occidentalis on tobacco field was evaluated by comparing the population of F. occidentalis under different releasing times and methods. The application of N. barkeri on tobacco and weeds for three times had the best control effect on the population of F. occidentalis, and the maintenance time was the longest, with the highest relative control effect of 58.02%. The control effect of twice application of the N. barkeri was the second, and the highest relative control effect was 55.57%. While the control effect on F. occidentalis was the worst after only one application of N. barkeri, and the highest relative control effect was only 49.96% and the duration of the control effect was the shortest. At the same application time, the control effect of N. barkeri applied only to tobacco plant was slightly higher than that only to the weeds, but there was no significant difference between them. The simultaneous release of N. barkeri on tobacco and weeds in tobacco fields can better control F. occidentalis, and the release of N. barkeri on tobacco and weeds at least twice during the tobacco field period (the interval is about 15 days) can achieve relatively good control effect. When the cost is allowed, the more the number of releases of N. barkeri, the better the prevention and control effect on thrips such as F. occidentalis.