ABSTRACT

The Scotch broom gall mite, Aceria genistae, is an adventive herbivore of Cytisus scoparius (Scotch broom), an invasive non-native shrub in California, USA. Although feeding by these mites clearly induces localised tissue distortion, the effect of A. genistae on overall host vigour and reproduction has not been assessed. Here we compare biomass allocation across various plant organs between two groups, heavily or lightly galled plants, at three northern California sites. Most structural components, including plant height, stem biomass, and leaf biomass, were similar regardless of galling intensity. However, both canopy volume and seeds per plant were reduced in heavily versus lightly galled plants; seeds were reduced up to 80% among larger plants. Collectively, these data suggest A. genistae galls are produced at the cost of seed production. Aceria genistae is a relatively new arrival in California but is already causing measurable effects to plant performance, which are expected to increase over time as mite populations increase and its range expands. Intentionally redistributing this mite is currently illegal in the USA, and this research is part of a broader investigation to inform the biological control agent permit process.

摘要

苏格兰扫帚瘿螨（Aceria genistae ）是Cytisus scoparius （苏格兰扫帚）的一种外来草食动物，是美国加利福尼亚州的一种入侵性非本地灌木。尽管这些螨虫的摄食明显会引起局部组织变形，但A. genistae的影响尚未评估对总体宿主活力和繁殖的影响。在这里，我们比较了北加州三个地点的两组（重度或轻度损伤植物）之间不同植物器官的生物量分配。大多数结构成分，包括株高、茎生物量和叶生物量，无论磨损强度如何，都是相似的。然而，与轻度瘿伤植物相比，严重伤瘿植物的冠层体积和每株植物的种子均减少；较大植物的种子数量减少了 80%。总的来说，这些数据表明A. genistae虫瘿是以种子生产为代价的。银杏这种螨虫在加利福尼亚州相对较新，但已经对植物性能产生了可测量的影响，随着螨虫数量的增加和范围的扩大，这种影响预计会随着时间的推移而增加。目前在美国故意重新分布这种螨虫是非法的，这项研究是更广泛调查的一部分，旨在为生物防治剂许可流程提供信息。