Interactions between Orius albidipennis (Heteroptera: Anthocoridae) and Neoseiulus cucumeris (Acari: Phytoseiidae): Effects of host plants under microcosm condition

In three-dimensional microcosm set-ups we explored the influence of host plant traits of cucumber, eggplant and sweet pepper on the interactions between minute pirate bugs, Orius albidipennis (Reuter) and predatory mites, Neoseiulus cucumeris (Oudemans) in the presence of extraguild prey, Thrips tabaci Lindeman. The host plant influenced the population development of thrips with sweet pepper being most inferior and cucumber being the best for egg laying and/or juvenile development and survival. No host plant effect was found on the survival of adult thrips. The host plant also influenced the biocontrol efficiency of O. albidipennis which, on its own, significantly reduced thrips populations on sweet pepper and eggplant, but not on cucumber. A similar host plant effect was not seen for N. cucumeris which, on its own, was unable to reduce thrips populations on either of the host plants. No additive or synergistic effect between the two predators was observed. Finally, the host plant influenced the interactions between the two predators—when both predators were present, a significant reduction in the density of adult mites was observed on cucumber and sweet pepper, presumably a result of intraguild predation from O. albidipennis. No influence of O. albidipennis on the predatory mites was found on eggplant and on none of the host plants was a negative influence observed on mite eggs or nymphs. The results point to the importance of including host plant aspects in studies aimed at evaluations of possible interactions between beneficials intended for simultaneous applications for biocontrol.