A pilot study to determine the extent of possible biocontrol resistance in St. John's wort, the effect of St.John's wort on forage availability and alternative tools for control.

圣约翰草（贯叶连翘）是一种原产于欧洲的多年生植物，能够迅速繁殖和传播，特别是在受干扰的地点和牧场。圣约翰草于1947年首次在不列颠哥伦比亚省被发现，是一种优秀的竞争对手；它减少了本地植物物种，并可能在此过程中伤害牲畜。圣约翰草的叶子中含有化学物质金丝桃素和金丝桃素。摄入金丝桃素**会导致牲畜起水泡、繁殖能力下降，在极少数情况下还会导致死亡。据报道，hyperperin是一种对草食的防御性化合物。**生物防治虫金曲虫（Chrysolina hyperici）在历史上是一种有效的圣约翰草生物防治虫。在不列颠哥伦比亚省南部，这种甲虫的处理使圣约翰草的数量减少到不到预处理水平的2%。不幸的是，观察表明，圣约翰草在景观中重新出现，生物防治甲虫的表现不如历史上那样好。已知压力源，如草食，会触发植物的形态和化学捕食者防御机制，如毒素的产生。圣约翰草可能有能力过量产生毒素金丝桃素和超丝桃素，作为对甲虫食草的一种掠食性防御机制。**为了解决圣约翰草在不列颠哥伦比亚省复活的问题，需要新的方法来控制圣约翰草。陶氏化学的除草剂在历史上曾有效地控制过圣约翰草。如果圣约翰草种群对生物防治甲虫产生了抗性，则可能需要使用这种除草剂。我们将**确定BC省3个地点是否存在生物防治抗性和抗性程度。我们将与**Corteva Agriscience合作：1)确定圣约翰草种群是否存在生物防治抗性2)**测试不同Corteva Agriscience除草剂对圣约翰草种群的药效；3)我们将介绍简单的田间技术，用于鉴定潜在抗性植物和圣约翰草的替代杂草控制方案。

St. John's wort (Hypericum perforatum) is a perennial plant native to Europe that can reproduce and spread**aggressively, particularly in disturbed sites and rangelands. St. John's wort was first document in British**Columbia in 1947 and is an excellent competitor; it diminishes native plant species and can harm livestock in**the process. St. John's wort contains the chemicals hypericin and hyperforin in its leaves. Ingestion of hypericin**results in blisters, reduced reproductive performance, and in rare cases, death in livestock. Hyperforin has been**reported to serve as a defensive compound in response to herbivory.**The biocontrol beetle, Chrysolina hyperici, has historically been an effective biocontrol of St. John's wort. In**southern BC treatment by the beetle as reduced St. John's wort populations to less than 2% of pretreatment**levels. Unfortunately, observations indicate that St. John's wort is resurging on the landscape and the biocontrol**beetles are not performing as well as they have historically. Stressors, such as herbivory, are known to trigger**morphological and chemical predator defense mechanisms in plants, such as the production of toxins. St.**John's wort may have the ability to overproduce toxins hypericin and hyperforin as a predatory defense**mechanism in response to beetle herbivory.**To tackle the issue of resurging St. John's wort in BC, new methods are needed to control St. John's wort. Dow**has herbicides that have historically been effective at controlling St. John's wort. The use of this herbicide may**be needed if the population of St. John's wort has developed resistance to the biocontrol beetle. We will**determine if biocontrol resistance exists and the extent of resistance at 3 sites in BC. We will collaborate with**Corteva Agriscience to: 1) determine if biocontrol resistance is present within St. John's wort populations 2)**test the efficacy of different Corteva Agriscience herbicides on St John's wort populations; and 3) we will**present simple field based techniques for identifying potentially resistant plants and alternative weed control**options for St.John's wort control.