Abstract The polyphagous shot hole borer (PSHB) and the Kuroshio shot hole borer (KSHB) are newly invasive ambrosia beetles in California. They are vectors of the plant pathogen Fusarium euwallaceae (S. Freeman, Z. Mendel, T. Aoki, K. O’ Donnell), the causal agent of Fusarium dieback in a broad host range that includes commercial avocados, landscape trees, and native tree species in urban and wildland environments. Management of these beetles using contact insecticides is challenging because the beetles spend little time outside their hosts. Trunk injection of systemic insecticides has been proposed as an alternative to contact treatments because insecticides can more effectively target the vascular tissues where the beetles establish their colonies. In this study, several field trials were conducted to evaluate the efficacy of trunk injections of the systemic insecticide emamectin benzoate in avocado trees. The uptake and persistence of emamectin benzoate were determined by quantifying residues in wood cores sampled at various heights within the trees where beetles would likely target. In conjunction with the field trials, a series of bioassays was conducted with a KSHB colony using an avocado-based artificial diet infused with the insecticide. The bioassays showed a dose-dependent effect of emamectin benzoate on the survival and development of the beetle in diet. We derived a tentative working threshold of 300 ng/g insecticide from the bioassay data that we subsequently used as a guide in evaluating the efficacy of the trunk injections. Emamectin benzoate established quickly within trees at the threshold concentration in the areas most vulnerable to attack and colonization by KSHB. Injection of the insecticide in a more dilute form promoted both faster uptake and more rapid establishment of effective concentrations than the undiluted form, thereby providing potential options in how the material is injected based on the levels of infestation of groves.

中文翻译：

---

评估树干注射苯甲酸阿维菌素作为加利福尼亚鳄梨树黑潮小孔蛀虫的潜在管理策略

摘要 多食性炮孔螟（PSHB）和黑潮炮孔螟（KSHB）是加利福尼亚州新近入侵的豚草甲虫。它们是植物病原体 Fusarium euwallaceae (S. Freeman, Z. Mendel, T. Aoki, K. O' Donnell) 的载体，Fusarium 枯死在广泛的宿主范围内，包括商业鳄梨、景观树和本地城市和荒地环境中的树种。使用接触杀虫剂管理这些甲虫具有挑战性，因为甲虫在宿主之外的时间很少。全身性杀虫剂的树干注射已被提议作为接触治疗的替代方法，因为杀虫剂可以更有效地针对甲虫建立集落的维管组织。在这项研究中，进行了几项田间试验，以评估在鳄梨树中向树干注射全身性杀虫剂苯甲酸阿维菌素的功效。通过量化在甲虫可能瞄准的树木内不同高度采样的木芯中的残留物来确定甲虫的吸收和持久性。结合田间试验，使用注入杀虫剂的鳄梨人工饲料对 KSHB 菌落进行了一系列生物测定。生物测定显示甲虫在饮食中对甲虫的存活和发育具有剂量依赖性影响。我们从生物测定数据中推导出 300 ng/g 杀虫剂的暂定工作阈值，我们随后将其用作评估树干注射效果的指南。在最容易受到 KSHB 攻击和定植的区域，依维菌素苯甲酸盐在树内以阈值浓度迅速建立。与未稀释的形式相比，以更稀释的形式注射杀虫剂促进了更快的吸收和更快地建立有效浓度，从而根据树林的侵染水平提供了如何注射材料的潜在选择。