Abstract

Biodiversity and food web ecology are interconnected in the study of community dynamics, being related to underlying factors, such as complexity, productivity, and community assembly. Biodiversity can contribute to increasing the ecosystem function, but its effect on consumer trophic levels remains inconclusive. We generated a multitrophic seed-herbivore-parasitoid food web based on seed traits, insect species abundance and richness, structural and functional food web attributes and the relationship between the seed biomass and the number of eggs laid by the herbivorous beetle Stator maculatophygus. We hypothesized that the food web structure (i.e., connectivity, linkage density and connectance) was determined by the parasitoid trophic levels. Our second hypothesis was that food web functionality (e.g., the parasitism rate) was not affected by the dominance of a single parasitoid species. From the seeds of a plant species (Senegalia tenufolia) (primary trophic level), we recorded nine species and four trophic levels, with one herbivore and seven parasitoids. A significant positive relationship was found between the number of eggs laid and the seed biomass. Connectivity and linkage density were affected by the parasitoid trophic level, and the dominance of a single parasitoid species led to decreases in the structural complexity and the parasitism rate. We described the relationship between structure and function in the field in a multitrophic host-parasitoid food web. The biodiversity of parasitoids plays an important role in the food web, maintaining its complexity and functionality. Synergies between processes acting at lower and higher levels may be driving the food web patterns presented here.

Implications for insect conservation

Our results highlight the positive role of parasitoid insect biodiversity in the biological population control of herbivorous insects in this microhabitat (fruit/seed). This demonstrates the importance of public policies aimed at the conservation of natural areas to maintain the diversity and ecosystem functions performed by parasitoid insects.

中文翻译：

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主要寄生物种减少了食物网结构的复杂性和功能

摘要

生物多样性和食物网生态在群落动态研究中相互关联，与复杂性、生产力和群落组装等潜在因素相关。生物多样性有助于增加生态系统功能，但其对消费者营养水平的影响仍无定论。我们根据种子性状、昆虫物种的丰度和丰富度、结构和功能食物网属性以及种子生物量与草食性甲虫Stator maculatophygus产卵数量之间的关系，生成了一个多营养种子-食草动物-寄生蜂食物网. 我们假设食物网结构（即连接性、连接密度和连接性）由寄生蜂的营养水平决定。我们的第二个假设是食物网功能（例如，寄生率）不受单一寄生物种优势的影响。来自一种植物的种子 ( Senegalia tenufolia)（初级营养级），我们记录了 9 个物种和 4 个营养级，其中包括 1 个食草动物和 7 个寄生蜂。产卵数与种子生物量之间存在显着的正相关关系。连接性和连锁密度受寄生蜂营养水平的影响，单一寄生蜂物种的优势导致结构复杂性和寄生率下降。我们描述了多营养宿主 - 寄生生物食物网中结构和功能之间的关系。寄生蜂的生物多样性在食物网中发挥着重要作用，保持其复杂性和功能性。在较低和较高层次上起作用的过程之间的协同作用可能会推动这里呈现的食物网模式。

对昆虫保护的影响

我们的结果强调了寄生昆虫生物多样性在该微生境（水果/种子）中食草昆虫的生物种群控制中的积极作用。这表明旨在保护自然区域以维持寄生昆虫的多样性和生态系统功能的公共政策的重要性。