Krey Karol L, Blubaugh Carmen K, Van Leuven James T, Snyder William E
Department of Entomology, Washington State University, Pullman, WA.
Department of Plant and Environmental Sciences, Clemson University, Clemson, SC.
Environ Entomol. 2019 Dec 2;48(6):1323-1330. doi: 10.1093/ee/nvz100.
Soil chemistry and microbial diversity can impact the vigor and nutritive qualities of plants, as well as plants' ability to deploy anti-herbivore defenses. Soil qualities often vary dramatically on organic versus conventional farms, reflecting the many differences in soil management practices between these farming systems. We examined soil-mediated effects on herbivore performance by growing potato plants (Solanum tuberosum L.) in soils collected from organic or conventional commercial farm fields, and then exposing these plants to herbivory by green peach aphids (Myzus persicae Sulzer, Hemiptera: Aphididae) and/or Colorado potato beetles (Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae). Responses of the two potato pests varied dramatically. Survivorship of Colorado potato beetles was almost 3× higher on plants grown in organic than in conventional soils, but was unaffected by the presence of aphids. In contrast, aphid colony growth was twice as rapid when aphids were reared alone rather than with Colorado potato beetles, but was unaffected by soil type. We saw no obvious differences in soil nutrients when comparing organic and conventional soils. However, we saw a higher diversity of bacteria in organic soils, and potato plants grown in this soil had a lower carbon concentration in foliar tissue. In summary, the herbivore species differed in their susceptibility to soil- versus competitor-mediated effects, and these differences may be driven by microbe-mediated changes in host plant quality. Our results suggest that soil-mediated effects on pest growth can depend on herbivore species and community composition, and that soil management strategies that promote plant health may also increase host quality for pests.
土壤化学性质和微生物多样性会影响植物的活力和营养品质，以及植物部署抗食草动物防御的能力。有机农场和传统农场的土壤质量往往差异很大，这反映了这两种耕作系统在土壤管理实践上的诸多差异。我们通过在从有机或传统商业农田采集的土壤中种植马铃薯植株（Solanum tuberosum L.），然后让这些植株遭受桃蚜（Myzus persicae Sulzer，半翅目：蚜科）和/或科罗拉多马铃薯甲虫（Leptinotarsa decemlineata Say，鞘翅目：叶甲科）的取食，来研究土壤介导的对食草动物表现的影响。两种马铃薯害虫的反应差异很大。科罗拉多马铃薯甲虫在有机土壤中生长的植株上的存活率几乎是在传统土壤中生长植株的3倍，但不受蚜虫存在的影响。相比之下，单独饲养蚜虫时蚜虫群体的生长速度是与科罗拉多马铃薯甲虫一起饲养时的两倍，但不受土壤类型的影响。在比较有机土壤和传统土壤时，我们没有发现土壤养分有明显差异。然而，我们发现有机土壤中的细菌多样性更高，在这种土壤中生长的马铃薯植株叶片组织中的碳浓度较低。总之，食草动物物种对土壤介导和竞争者介导的影响的敏感性不同，这些差异可能由微生物介导的寄主植物质量变化所驱动。我们的结果表明，土壤介导的对害虫生长的影响可能取决于食草动物物种和群落组成，并且促进植物健康的土壤管理策略也可能提高害虫的寄主质量。
