We evaluated the effectiveness of using a blend of volatiles that attract Cotesia vestalis, a specialist parasitoid wasp of diamondback moth (DBM) larvae, to control DBM larvae on cabbage plants under open field conditions. We set three dispensers of the synthetic C. vestalis attractant together with one sugary-food feeder in a cabbage plot (10 m × 1 m; the treated plot) on one side of a pesticide-free open agricultural field (approximately 20 m × 20 m) from June to September in 2010, and July to August in 2011. On the other side of the field, we created a control cabbage plot of the same size in which neither dispensers nor a feeder were set. The incidences of DBM larvae and C. vestalis cocoons in the control and treated plots were compared. Poisson regression analyses of the number of DBM larvae and C. vestalis cocoons were also conducted. In 2010, the incidence of DBM larvae in the treated plot was significantly lower than that in the control plot. Poisson regression analyses in 2010 showed that the rate of increase in the number of C. vestalis cocoons along with an increase in the number of DBM larvae in the treated plot was significantly higher than that in the control plot. In 2011, the incidence in both the treated and control plots remained low (5 larvae per plant or less), with no significant difference between the plots. Poisson regression analyses in 2011 showed that the number of C. vestalis cocoons in the treated plot was significantly higher than that in the control plot, irrespective of the number of DBM larvae. The incidence of Pieris rapae larvae and Plusiinae spp. was not affected by the treatments. The number of aphids in the treated and control plots was inconsistent between the two years. Based on these two-year results, the possible use of C. vestalis attractants in open agricultural fields is discussed.

中文翻译：

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使用合成草食性植物挥发物来吸引专科寄生蜂 Cotesiavestalis，用于控制开放农田中小菜蛾幼虫的发病率

我们评估了使用吸引小菜蛾 (DBM) 幼虫的专业寄生蜂 Cotesiavestalis 的挥发物混合物在大田条件下控制卷心菜植物上的 DBM 幼虫的有效性。我们在无农药开放农田（约 20 m × 20 m) 2010 年 6 月至 9 月和 2011 年 7 月至 8 月。在田地的另一边，我们创建了一个相同大小的对照白菜地块，其中既没有设置分配器也没有设置喂食器。比较了对照和处理地块中 DBM 幼虫和 C.vestalis 茧的发生率。还进行了 DBM 幼虫和 C.vestalis 茧数量的泊松回归分析。2010年，处理小区DBM幼虫发生率明显低于对照小区。2010 年泊松回归分析表明，处理小区的前庭小蠹虫茧数和 DBM 幼虫数量的增加率显着高于对照小区。2011 年，处理地块和对照地块的发病率仍然很低（每株 5 只幼虫或更少），地块之间没有显着差异。2011 年的泊松回归分析表明，无论 DBM 幼虫的数量如何，处理区中的 C.vestalis 茧数量均显着高于对照区中的数量。Pieris rapae幼虫和Plusiinae spp的发病率。不受治疗影响。两年间，处理地块和对照地块中的蚜虫数量不一致。基于这两年的结果，讨论了在开放农田中使用 C.vestalis 引诱剂的可能性。