Conduct pairwise choice trials
Pairwise choice trials (N = 69) of captive beetles and mites were conducted to evaluate whether mites discriminated between paired wild-caught male N. investigator beetles of different sizes. Ten P. carabi were selected at random from the large size-class mite colony and placed in a cylindrical plastic vial that was ~8 cm in height and ~4 cm in diameter. The vial was occasionally tapped to keep the mites at the bottom where they would encounter the beetles. After 5 min, the beetles were separated and a stream of carbon dioxide was used to remove the mites. The number of mites clinging to each beetle was counted, the mites were returned to the colony, and the beetles were returned to their individual plastic holding containers.
Quantities: 69 pairwise choice trials, 10 mites per trial, ~8 cm height × ~4 cm diameter vialDuration: 5 min per trialConditions: Laboratory conditions
Equipment: cylindrical plastic vial, carbon dioxide, pipette
Conduct nutritional status trials
Beetle pairs (N = 37) were assigned to nutritional condition experiments after the pairwise choice trials. One beetle within each pair was selected at random to receive a surplus of chicken meat in its container, whereas the other beetle remained unfed. After 2 or 4 d under these feeding conditions, beetle pairs were tested for mite preference using the same protocol as the first pairwise choice trial.
Quantities: 37 beetle pairs, surplus chicken meat provided to one beetle per pairDuration: 2 or 4 days of feeding treatment followed by choice trialConditions: Laboratory conditions with controlled feeding