Plant-mediated resource partitioning by coexisting parasitoids.

Area of Science:

• Ecology
• Community Ecology
• Insect Ecology

Background:

• Resource partitioning is theorized to be mediated by non-adjacent trophic levels, but empirical evidence is limited.
• Parasitoids sharing a host may experience resource partitioning influenced by their host plant.
• The Tibetan Plateau's alpine meadows host diverse insect communities, including parasitoids and their hosts.

Purpose of the Study:

• To investigate if plants mediate resource partitioning for two parasitoid species sharing a common herbivorous host.
• To determine the role of plant traits in influencing predator-prey dynamics between parasitoids and a tephritid fly.
• To provide empirical evidence for the influence of non-adjacent trophic interactions on species coexistence.

Main Methods:

• Field surveys and molecular barcoding to identify parasitoid-host relationships.
• Microcosm experiments to test parasitoid foraging success based on host plant.
• Analysis of plant traits (capitula size) and their impact on parasitoid behavior (ovipositor length, food limitation).

Main Results:

• The identity of the main parasitoid predator of the tephritid fly (Tephritis femoralis) depended on the host plant (Saussurea nigrescens or Anaphalis flavescens).
• Pteromalus albipennis primarily preyed on flies from S. nigrescens, while Mesopolobus sp. targeted flies from A. flavescens.
• Plant traits, specifically capitula size, limited parasitoid exploitation: P. albipennis faced food limitation in A. flavescens, and Mesopolobus sp. could not reach hosts in S. nigrescens.

Conclusions:

• Plant traits can mediate resource partitioning for parasitoids, facilitating the coexistence of species that share a common host.
• Bottom-up control by plant species traits influences interactions at higher trophic levels.
• Non-adjacent trophic interactions, mediated by plants, can promote species coexistence and biodiversity in ecological communities.