Community structure in ichneumonid parasitoids at different spatial scales.

Area of Science:

• Ecology
• Community Ecology
• Insect Ecology

Background:

• Parasitoid community structure processes remain poorly understood.
• Niche-apportionment models offer insights into assemblage rules.
• Previous studies focused on single host species and populations, limiting broader ecological understanding.

Purpose of the Study:

• To compare patterns of relative abundances generated by five niche-apportionment models with observed data.
• To investigate parasitoid community structure across multiple hosts and spatial scales.
• To assess the consistency of ecological structuring processes in Ichneumonidae assemblages.

Main Methods:

• Applied five stochastic niche-apportionment models to observed parasitoid assemblages.
• Collected data from two Ichneumonidae sub-families (Diplazontinae and Pimplinae) in Yorkshire, UK.
• Analyzed data at both landscape and patch spatial scales.

Main Results:

• Three of the five models significantly differed from observed patterns across all taxonomic levels and scales.
• Diplazontinae assemblages fit the random fraction (RF) model at the landscape scale in broadleaved woods, suggesting hierarchical structuring.
• Pimplinae fit the RF model only at the patch scale; Pimplini tribe fit the random assortment (RA) model at both scales, indicating unsaturated assemblages, while Ephialtini tribe fit no model.

Conclusions:

• Ecological processes structuring ichneumonid parasitoid assemblages are not consistent across taxa.
• Spatial scale plays a crucial role in determining which niche-apportionment models best describe community structure.
• The findings highlight the complexity of insect community assembly and the need for scale-dependent ecological interpretations.