Diet-dependent intraguild predation between the predatory mites Neoseiulus californicus and Neoseiulus cucumeris

Abstract

Based on the hypothesis that matching diets of intraguild (IG) predator and prey indicate strong food competition and thus intensify intraguild predation (IGP) as compared to non-matching diets, we scrutinized diet-dependent mutual IGP between the predatory mites Neoseiulus cucumeris and N. californicus. Both are natural enemies of herbivorous mites and insects and used in biological control of spider mites and thrips in various agricultural crops. Both are generalist predators that may also feed on plant-derived substances such as pollen. Irrespective of diet (pollen or spider mites), N. cucumeris females had higher predation and oviposition rates and shorter attack latencies on IG prey than N. californicus. Predation rates on larvae were unaffected by diet but larvae from pollen-fed mothers were a more profitable prey than those from spider-mite fed mothers resulting in higher oviposition rates of IG predator females. Pollen-fed protonymphs were earlier attacked by IG predator females than spider-mite fed protonymphs. Spider mite-fed N. californicus females attacked protonymphs earlier than did pollen-fed N. californicus females. Overall, our study suggests that predator and prey diet may exert subtle influences on mutual IGP between bio-control agents. Matching diets did not intensify IGP between N. californicus and N. cucumeris but predator and prey diets proximately influenced IGP through changes in behaviour and/or stoichiometry.