Shah PA, Aebi M, Tuor U
Mikrobiologisches Institut, Eidgenossische Technische Hochschule, CH-8092 Zurich, Switzerland.
Appl Environ Microbiol. 1998 Nov;64(11):4260-3. doi: 10.1128/AEM.64.11.4260-4263.1998.
Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.
新蚜虫疠霉是一种在全球范围内对蚜虫害虫具有重要影响的真菌病原体。很少有关于将这种天然制剂用于生物防治的报道。在当前的研究中，对将新蚜虫疠霉菌丝固定在藻酸盐基质中的相关因素进行了研究。在液体培养基中培养的两个分离株的菌丝长度为220至620μm，直径为7至19μm，细胞质含量为74至83%。用于从包埋菌丝中产生分生孢子的低粘度海藻酸钠的最佳浓度为1.5%（重量/体积），0.1和0.25M的氯化钙同样适合用作胶凝溶液。胶凝后用10%的蔗糖冲洗藻酸盐珠。然而，珠子在0.1M氯化钙或10%蔗糖中放置的时间不应超过40分钟，以防止分生孢子产量损失10%。40%（体积/体积）浓度的真菌生物量产生的分生孢子明显多于20%或标准浓度10%。即使珠子在层流罩中过夜干燥并在4℃下储存4天，这种效果仍然存在。通过标准化实验室生物测定法确定，新鲜制备的藻酸盐珠产生的分生孢子在豌豆蚜中引起27%至32%的感染。这一结果与接种新鲜菌丝垫或培养皿培养物中的菌块的蚜虫感染情况没有显著差异。总之，藻酸盐包埋似乎是一种在蚜虫害虫生物防治中利用新蚜虫疠霉的有前景的技术。
