ABSTRACT

Invasive ambrosia beetles and their symbiotic fungi are responsible for destructive diseases like Laurel Wilt and Fusarium Dieback. Some biological treatments and chemical pesticides (e.g. malathion) have been proposed as alternatives to control these pests, however, to date there are no effective treatments. Here we evaluated the susceptibility of the ambrosia beetle Xyleborus affinis Eichhoff to the entomopathogenic fungus Metarhizium robertsii strain Xoch 8.1, and the efficacy of the mycopathogenic fungus Trichoderma asperellum strain Th-T4 (3) to inhibit the growth of the pathogenic ambrosia fungus Fusarium euwallaceae strain 744. Also, we compared the efficacy of a combination of M. robertsii Xoch 8.1 and T. asperellum Th-T4 (3) against X. affinis, and examined the feasibility of using this combination as an alternative to reduce the malathion doses that have been proposed to control ambrosia beetles. The treatment of X. affinis with M. robertsii (1 × 10⁷ con/mL) alone or in combination with T. asperellum (1 × 10⁶ con/mL) resulted in an average mortality of 76% (±7.5), which was statistically similar to that obtained with malathion at 600 ppm (96% ± 4.0). The combination of a lower concentration of malathion (60 ppm or 200 ppm) and both fungi was as efficient as malathion at 600 ppm. Mortality in negative controls (without fungal conidia or malathion) resulted in an average of 16% (±7.5). The proposed combined treatment reduces by up to one order of magnitude the required amount of malathion, and thus represents a potential alternative to control ambrosia beetle pests.

摘要

入侵的金银花甲虫及其共生真菌是造成月桂枯萎病和枯萎病等破坏性疾病的原因。一些生物处理和化学杀虫剂（例如马拉硫磷）已被提议作为控制这些害虫的替代方法，但是，迄今为止还没有有效的处理方法。在这里，我们评估了甘草甲虫Xyleborus affinis Eichhoff 对昆虫病原真菌Metarhizium robertsii Xoch 8.1 的敏感性，以及真菌病原真菌Trichoderma asperellum Th-T4 (3) 抑制病原甘草真菌Fusarium菌株生长的功效744.此外，我们比较了M组合的功效。robertsii Xoch 8.1和Ť。asperellum Th-T4 (3) 对抗X. affinis，并检查了使用这种组合作为替代方案来减少马拉硫磷剂量的可行性，这些剂量已被提议用于控制甘草甲虫。治疗X. AFFINIS与M. robertsii（1×10 ⁷ CON / mL）的单独或组合与T.棘孢（1×10 ⁶con/mL) 导致平均死亡率为 76% (±7.5)，这与使用 600 ppm 马拉硫磷 (96% ± 4.0) 获得的死亡率在统计上相似。较低浓度的马拉硫磷（60 ppm 或 200 ppm）与两种真菌的组合与 600 ppm 的马拉硫磷一样有效。阴性对照（无真菌分生孢子或马拉硫磷）的死亡率平均为 16% (±7.5)。提议的联合处理将所需的马拉硫磷量减少了一个数量级，因此代表了控制甘草甲虫害虫的潜在替代方案。