Search

Plant diversity drives the trophic ecology of arthropod communities, and is the focus of thousands of studies and a growing field of meta-analysis. Although syntheses of plant diversity studies have yielded valuable insights, their sheer number and complexity limits broader interpretation. Here we scrutinize 23 syntheses published over three decades to identify common themes and contrasting results. We find that plant diversity consistently attracts more abundant and diverse communities of predators. Herbivore diversity tends to increase in response to plant diversity treatments, while herbivore abundance and plant damage generally decrease. Yet, these net effects often mask nuanced responses to plant diversity that depend on ecosystem, scale, and specialization. For instance, specialist herbivores often respond negatively to plant diversity, while generalists more often mount positive or neutral responses. Studies conducted at greater spatial scales show a dilution of effects on herbivores, but reveal conflicting effects on predators. Despite complexity in outcomes, syntheses show that diversifying plant communities holds great promise for enhancing the resilience of managed ecosystems. A closer examination of how insect diet breadth, spatial scale, and plant arrangement interactively determine the strength of trophic cascades will improve reliability and precision in how we leverage biodiversity for conservation and biocontrol. [ABSTRACT FROM AUTHOR]

Hyperparasitoids are some of the most diverse members of insect food webs. True hyperparasitoids parasitize the larvae of other parasitoids, reaching these larvae with their ovipositor through the herbivore that hosts the parasitoid larva. During pupation, primary parasitoids also may be attacked by pseudohyperparasitoids that lay their eggs on the parasitoid (pre)pupae. By attacking primary parasitoids, hyperparasitoids may affect herbivore population dynamics, and they have been identified as a major challenge in biological control. Over the past decades, research, especially on aphid- and caterpillar-associated hyperparasitoids, has revealed that hyperparasitoids challenge rules on nutrient use efficiency in trophic chains, account for herbivore outbreaks, or stabilize competitive interactions in lower trophic levels, and they may use cues derived from complex interaction networks to locate their hosts. This review focuses on the fascinating ecology of hyperparasitoids related to how they exploit and locate their often inconspicuous hosts and the insect community processes in which hyperparasitoids are prominent players. [ABSTRACT FROM AUTHOR]