Data from: Classical biological control and apparent competition: evaluating a waterhyacinth invaded community module

The scope and complexity of interactions within community food webs necessitates their simplification to a community module scale for conducting empirical studies. An outdoor mesocosm study in the USA quantified the strengths of direct and indirect interactions between two herbivore congeners that fed on two aquatic plant species while sharing a parasitoid. Kalopolynema ema (Hymenoptera: Mymaridae) is a stenophagous native egg parasitoid that attacks the hemipteran species in this study, Megamelus davisi (Hemiptera: Delphacidae), a native herbivore that feeds on the native aquatic species Nuphar advena, and the introduced biological control agent Megamelus scutellaris (Hemiptera: Delphacidae) that feeds on the non-native aquatic species waterhyacinth, Pontederia crassipes. The presence of M. scutellaris did not significantly increase parasitism of M. davisi indicating that apparent competition was not a factor in this community module. There was no evidence of any trophic cascades caused by these interactions based on the relative growth rates of biomass and leaf area for both plant species. The relative strengths of interactions varied with herbivore densities suggesting that should negative indirect effects occur they would likely be transient and closely linked to population dynamics as influenced by abiotic factors like temperature. The primary negative interaction was biotic resistance to Megamelus scutellaris from attack by Kalopolynema ema. Despite identifying potential negative interactions using path analysis, we saw no apparent competition following the insertion of a weed biological control agent into a community that contains an ecological analog. Resources in this dataset:Resource Title: Indirect Effects SS mesocosm . File Name: MS Indirect Data Commons version.xlsxResource Description: Raw data from MS Indirect study in mesocosms. NA = Nuphar advena, WH = Pontederia crassipes, MD = Megamelus davisi, MS = M. scutellaris., KE = Kalopolynema ema, BGBM = below ground biomass.

社区食物网内部相互作用的范围与复杂性要求将其简化至社区模块尺度，以便进行实证研究。美国一项户外中尺度生态系统研究量化了两种食草同种生物之间，在共享一种寄生蜂的情况下，对两种水生植物物种的直接和间接相互作用强度。Kalopolynema ema（膜翅目：小蜂科）是一种狭食性的本土卵寄生蜂，攻击本研究中的半翅目物种Megamelus davisi（半翅目：网翅蝽科），后者是一种本土食草动物，以本土水生植物Nuphar advena为食，以及以引入的生物防治剂Megamelus scutellaris（半翅目：网翅蝽科）为食的非本土水生植物水菖蒲，Pontederia crassipes。M. scutellaris的存在并未显著增加M. davisi的寄生率，这表明在此社区模块中，表面竞争并非影响因素。基于两种植物物种的生物量及叶面积的相对增长率，没有发现由这些相互作用引起的任何营养级联效应。相互作用的相对强度随食草动物密度的变化而变化，这表明，如果发生负面的间接效应，它们可能是短暂的，并且与受非生物因素如温度影响的种群动态密切相关。主要的负面相互作用是Kalopolynema ema对Megamelus scutellaris的生物抵抗性。尽管通过路径分析识别了潜在的负面相互作用，但在将杂草生物防治剂插入包含生态类似物的社区后，我们没有观察到明显的竞争。本数据集中的资源包括：资源标题：间接效应SS中尺度生态系统研究。文件名：MS间接数据通用版.xlsx。资源描述：MS间接中尺度生态系统研究的原始数据。NA代表Nuphar advena，WH代表Pontederia crassipes，MD代表Megamelus davisi，MS代表M. scutellaris，KE代表Kalopolynema ema，BGBM代表地下生物量。