Abstract When an insect candidate is identified for classical biological control, the first step is to identify its fundamental host-range. An insect’s fundamental host range, however, is typically broader than its ecological host range. This discrepancy can lead to ‘false positives’ in host testing and hamper the development of potential agents. Here, we propose a novel tool for interpreting host-range tests and identifying ‘false positives’ by studying native insects closely related to the biological control candidate. We conduct a series of laboratory and field studies comparing the fundamental and ecological host ranges of Chrysochus auratus Fabricius (Coleoptera: Chrysomelidae), a beetle native to North America, and present throughout the range invaded by pale swallow-wort, Vincetoxicum rossicum (Kleopow) Barbar. (Apocynaceae). We use the results to re-evaluate the risk associated with releasing the closely-related European beetle, Chrysochus asclepiadeus (Pallas) (Coleoptera: Chrysomelidae), a biological control candidate for V. rossicum that has raised some concerns because of no-choice feeding on North American milkweed species (Asclepias spp.) during laboratory host-testing. Laboratory and greenhouse trials here show that native North American C. auratus adults can feed and complete larval development on several native Asclepias species (fundamental host range), however in the field where both closely-related plant genera are present, this species specialized only on plants in the genus Apocynum. It appears then that Asclepias species generate ‘false positives’ for Chrysochus beetles when only the fundamental host range is assessed in the laboratory, and there is a need to re-evaluate C. asclepiadeus for potential biocontrol in North America taking into account its ecological host-plant range. We advocate for the inclusion of closely-related native congeners, where appropriate species exist, to aid in interpreting host-plant testing for potential classical biological control agents.

中文翻译：

---

解释经典生物对照候选者的宿主测试结果：对天然同源物的研究能否改进这一过程？

摘要 当确定一种昆虫候选物用于经典生物防治时，第一步是确定其基本宿主范围。然而，昆虫的基本宿主范围通常比其生态宿主范围更广。这种差异会导致宿主测试中的“误报”并阻碍潜在代理的开发。在这里，我们提出了一种新工具，用于通过研究与生物控制候选物密切相关的本地昆虫来解释宿主范围测试和识别“假阳性”。我们进行了一系列实验室和实地研究，比较了 Chrysochus auratus Fabricius（鞘翅目：Chrysomelidae）的基本和生态宿主范围，这是一种原产于北美的甲虫，存在于整个被苍白的燕子麦汁、Vincetoxicum rossicum (Kleopow) 入侵的范围内巴巴。（夹竹桃科）。我们使用这些结果重新评估与释放密切相关的欧洲甲虫 Chrysochus asclepiadeus (Pallas)（鞘翅目：Chrysomelidae）相关的风险，这是 V. rossicum 的生物控制候选者，由于无选择喂养而引起了一些担忧在实验室宿主测试期间对北美乳草物种（Asclepias spp.）的研究。这里的实验室和温室试验表明，北美本土的 C. auratus 成虫可以在几种本土马利筋属物种（基本寄主范围）上进食并完成幼虫发育，但是在存在两种密切相关植物属的领域中，该物种仅专门从事罗布麻属植物。当在实验室中仅评估基本宿主范围时，似乎马利筋属物种对 Chrysochus 甲虫产生“假阳性”，考虑到其生态寄主植物范围，需要重新评估 C. asclepiadeus 在北美的潜在生物防治。我们提倡在存在合适物种的情况下包含密切相关的本地同源物，以帮助解释宿主植物对潜在经典生物防治剂的测试。