Linked indirect effects in ant-phorid interactions: impacts on ant assemblage structure.

Area of Science:

• Ecology
• Behavioral Ecology
• Community Ecology

Background:

• Interaction modifications occur when one species' presence changes a second species' behavior, affecting its interactions with a third.
• Phorid parasitoids are species-specific and target ants at food resources, potentially altering competitive interactions between host ants and other species.

Purpose of the Study:

• To investigate if interaction modifications involving the phorid fly parasitoid, Apocephalus sp. 8, its host Pheidole diversipilosa, and competing ant species influence P. diversipilosa's foraging success.
• To determine how varying food resource size affects P. diversipilosa's resource capture ability and if this modifies the interaction modifications.

Main Methods:

• Observational studies at food resources involving P. diversipilosa, Apocephalus sp. 8, and various competitor ant species.
• Quantification of P. diversipilosa's foraging success under different parasitism and resource competition scenarios.
• Analysis of the impact of resource size on ant foraging and parasitoid success.

Main Results:

• Resource competition between P. diversipilosa and other ants enhances parasitoid host location.
• Parasitism significantly reduces P. diversipilosa's resource capture ability during interspecific competition.
• Competitor ant species benefit from these interaction modifications, with benefits correlating to their abundance.
• Resource size affects P. diversipilosa's capture success, but parasitism and resource size independently influence resource turnover.

Conclusions:

• Interaction modifications mediated by phorid fly parasitoids play a crucial role in shaping ant community structure.
• The presence of parasitoids and interspecific competition create complex dynamics that alter foraging success and competitive outcomes.
• Understanding these indirect ecological effects is vital for predicting ant assemblage organization.