Multiple parasitoid species enhance top-down control, but parasitoid performance is context dependent

Area of Science:

• Ecology
• Community Ecology
• Insect Ecology

Background:

• Ecological communities feature complex species interactions forming networks.
• Environmental changes disrupt these networks, altering species composition and interactions.
• Understanding drivers of interaction outcomes (network structure vs. species identity) is crucial for predicting community function.

Purpose of the Study:

• To disentangle the effects of network structure and species identity on consumer-resource interactions.
• To investigate how different community modules and species compositions influence host suppression and parasitoid performance.
• To assess the role of parasitoid diversity in ecological community functioning.

Main Methods:

• Utilized a host-parasitoid system in a laboratory experiment.
• Employed four distinct community modules representing different network structures.
• Assembled nine species combinations per module using three Drosophila hosts and three parasitoid species.

Main Results:

• Multiple parasitoid species increased host suppression via sampling effects, weaker interspecific competition, and synergism.
• Network structure effects on parasitoid performance were species-specific and context-dependent.
• Parasitoid performance varied based on the identity of co-occurring parasitoid or alternative host species.

Conclusions:

• Multiple parasitoid species generally enhance top-down control in ecological communities.
• The performance of parasitoids is contingent on the specific identities of interacting species.
• Preserving parasitoid diversity is vital for ecosystem functioning, as species-specific interactions influence outcomes sensitive to environmental change.