Challenging the Preference-Performance Hypothesis in an above-belowground insect.

Area of Science:

• Ecology
• Evolutionary Biology
• Entomology

Background:

• The Preference-Performance Hypothesis (PPH) links female insect oviposition preference to offspring performance.
• PPH is well-studied in aboveground insects but less so for those with belowground larvae.
• The cabbage root fly (Delia radicum) presents an ideal model for studying both above- and belowground interactions.

Purpose of the Study:

• To quantitatively test the PPH in the cabbage root fly (Delia radicum).
• To assess oviposition preference and larval performance across different brassicaceous species and cultivars.
• To investigate the PPH at both intraspecific and interspecific scales.

Main Methods:

• Estimating female oviposition preference of Delia radicum on Brassica oleracea, Brassica rapa, and Sinapis alba.
• Quantifying larval performance via survival and adult life-history traits (LHT) on selected plant species and cultivars.
• Comparing preference and performance data at intraspecific (within B. rapa and S. alba cultivars) and interspecific (between species) levels.

Main Results:

• The PPH was supported at the intraspecific scale for Brassica rapa, but only for certain life-history traits.
• No support for the PPH was found for Sinapis alba at the intraspecific scale.
• The PPH was not supported at the interspecific scale (between plant species).

Conclusions:

• The study highlights the complexity of the PPH, with varying support depending on the plant species, scale, and performance metrics used.
• It emphasizes the need to study insects with both above- and belowground life stages to understand host plant selection.
• Accurate testing of the PPH requires multiple performance variables and consideration of both intraspecific and interspecific plant variation.