Grapevine leafroll disease (GLD) affects grapevines worldwide. The primary causal agent of GLD is grapevine leafroll-associated virus 3 (GLRaV-3), which spreads to uninfected grapevines via mealybugs and soft-scale insects. Pseudococcus calceolariae (Hemiptera: Pseudococcidae) is a mealybug vector of GLRaV-3 in New Zealand. P. calceolariae also colonizes clovers (Trifolium spp.) growing naturally as vineyard ground cover. Separating mealybug from GLRaV-3 grapevine host could be enhanced by a trap plant: an alternative host attractive to and retentive of the target pest. We evaluated the association between P. calceolariae and ‘Grasslands Huia’ white clover (GHWC). GHWC seed was sown under grapevines in a commercial vineyard (14 × 0.4 ha plots); the control was under-vine herbicide use (7 × 0.4 ha plots, where only few Trifolium spp. plants grew). After 2 years, GHWC cover peaked at 40% mealybug infestation in 2019. From 2018 to 2021, P. calceolariae detection and abundance on GHWC was significantly higher than plants from the control plots. There was no treatment effect for mealybug infestation of grapevine leaves nor of GLRaV-3 incidence, independent of vintage. A glasshouse trial found no transmission of GLRaV-3 by P. calceolariae to any of 256 plants among five clover cultivars tested (Trifolium spp.), including GHWC; mealybug transmitted GLRaV-3 to 35 of 107 Nicotiana benthamiana plants. The results showed that in the 5-year period, added GHWC did not decouple P. calceolariae from the grapevine to reduce GLRaV-3 incidence, but rapid colonization of GHWC by mealybug and the lack of GLRaV-3 transmission to GHWC are encouraging. Further evaluation is needed to assess whether plant biodiversity can benefit a GLRaV-3 ecological management objective.

葡萄卷叶病（GLD）影响全世界的葡萄树。 GLD 的主要病原体是葡萄卷叶相关病毒 3 (GLRaV-3)，它通过粉蚧和软介虫传播到未受感染的葡萄树。 Pseudococcus calceolariae（半翅目：Pseudococcidae）是新西兰 GLRaV-3 的粉蚧载体。 P. calceolariae 还寄生在作为葡萄园地被植物自然生长的三叶草（三叶草属）上。诱捕植物可以增强将粉蚧与 GLRaV-3 葡萄藤宿主分离的效果：诱捕植物是一种对目标害虫具有吸引力和保留力的替代宿主。我们评估了 P. calceolariae 和‘Grasslands Huia’白三叶草 (GHWC) 之间的关联。 GHWC 种子播种在商业葡萄园的葡萄藤下（14 × 0.4 公顷地块）；对照是藤下除草剂的使用（7 × 0.4 公顷的地块，只生长了很少的三叶草属植物）。两年后，GHWC 覆盖率在 2019 年达到顶峰，粉蚧侵染率达 40%。从 2018 年到 2021 年，GHWC 上的蒲包 P. calceolariae 检测和丰度显着高于对照地块的植物。对于葡萄叶粉虱侵染和 GLRaV-3 发病率均没有治疗效果，与年份无关。一项温室试验发现，蒲包 P. calceolariae 没有将 GLRaV-3 传播到测试的 5 个三叶草品种（三叶草属）中的 256 种植物中的任何一种，包括 GHWC；粉蚧将 GLRaV-3 传播到 107 株本塞姆氏烟草中的 35 株。结果表明，在 5 年期间，添加 GHWC 并没有使蒲包 P. calceolariae 与葡萄藤脱钩，从而降低 GLRaV-3 发病率，但粉蚧在 GHWC 上的快速定殖以及 GLRaV-3 向 GHWC 传播的缺乏令人鼓舞。需要进一步评估植物生物多样性是否有利于 GLRaV-3 生态管理目标。