ABSTRACT

Sonchus oleraceus L. (Asteraceae), an annual species native to Eurasia and northern Africa, is among the most widely distributed plant species on Earth. In Australia, S. oleraceus, is a common weed in disturbed areas such as crop fields, pastures, gardens and roadsides. In agricultural settings, it can dominate fallows and cultivated fields where it uses stored soil moisture and reduces crop yield. This weed has also developed herbicide resistance, predicating the need for alternative management solutions. In this context, we undertook field surveys and preliminary host range studies in the native range of S. oleraceus to determine the feasibility of developing classical biological control solutions for Australia. Fifty-nine phytophagous arthropod species were recorded and nine pathogenic fungi were recovered from disease symptoms. Four arthropod species were selected for initial host-specificity testing based on information available in the literature. Preliminary host-specificity tests were also performed with representative isolate(s) of six of the pathogenic fungi. All these candidate agents were shown in the tests to affect key native species in Australia in the same subtribe as S. oleraceus (i.e. Sonchus hydrophilus and Actites megalocarpus). The results of our investigations suggest that classical biological control may not be a feasible option for the management of S. oleraceus in Australia, and that alternative integrated weed management tactics may need to be pursued to mitigate the impacts of this weed.

摘要

Sonchus oleraceus L.（菊科）是一种原产于欧亚大陆和北非的一年生物种，是地球上分布最广的植物物种之一。在澳大利亚，S. oleraceus是农田、牧场、花园和路边等受干扰地区的常见杂草。在农业环境中，它可以支配休耕地和耕地，在那里它使用储存的土壤水分并降低作物产量。这种杂草还产生了除草剂抗性，预示着需要替代管理解决方案。在此背景下，我们对S. oleraceus的原生范围进行了实地调查和初步寄主范围研究确定为澳大利亚开发经典生物控制解决方案的可行性。记录了 59 种植食性节肢动物，从疾病症状中恢复了 9 种病原真菌。根据文献中可获得的信息，选择了四种节肢动物物种进行初始宿主特异性测试。还对六种病原真菌的代表性分离株进行了初步宿主特异性测试。所有这些候选药物在测试中都显示影响与S. oleraceus相同亚部落中的澳大利亚关键本地物种（即 Sonchus hydrophilus和Actites megalocarpus）。我们的调查结果表明，传统的生物控制可能不是澳大利亚管理S. oleraceus的可行选择，可能需要采用替代的综合杂草管理策略来减轻这种杂草的影响。