The knotweed psyllid, Aphalara itadori, is a biological control agent for invasive knotweed species in North America and Europe. Initial releases were conducted in Canada in 2014 but establishment has been slow, seemingly as a result of low nymphal survival. We conducted two field experiments in Ontario, Canada, to explore the effects of native predators and the age of knotweed (Fallopia japonica) foliage on nymphal survival in A. itadori. Survival of A. itadori nymphs was significantly reduced on potted plants that were exposed to native predators in the field, compared to plants from which predators were excluded. The number of surviving nymphs was also significantly reduced on older F. japonica foliage, compared to recent regrowth after a summer cutting treatment. We discuss our findings in the context of biological invasion theory and emphasize the potential for increased overlap between the fields of invasion ecology and biological control. Finally, we advocate the use of A. itadori in combination with other control measures as part of an integrated pest management programme, rather than as a solitary measure. Specifically, we recommend that future releases of A. itadori be concentrated shortly after cutting or herbicide treatments in order to maximize the availability of young tender foliage.

中文翻译：

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生物防治剂Aphalara itadori的建立受到本地天敌和叶子年龄的限制

虎杖木虱Aphalara itadori是北美和欧洲入侵虎杖物种的生物防治剂。2014年在加拿大进行了首次发布，但建立起来很缓慢，这似乎是由于若虫存活率较低所致。我们在加拿大安大略省进行了两次现场试验，探索天敌的作用，虎杖（年龄虎杖）叶子上若虫生存A. itadori。与排除了天敌的植物相比，暴露于田间天敌的盆栽植物的Itadori若虫的存活率显着降低。较旧的日本粳稻的存活若虫数量也显着减少与经过夏季切割处理后的近期再生长相比，叶子较绿。我们在生物入侵理论的背景下讨论了我们的发现，并强调了入侵生态学和生物防治领域之间可能增加重叠的潜力。最后，我们提倡将意大利假单胞菌与其他控制措施结合使用，作为虫害综合治理计划的一部分，而不是单独措施。特别是，我们建议在修剪或除草剂处理后不久浓缩未来的A. itadori释放，以最大程度地利用嫩嫩的叶子。