Assessing the intraguild predation potential of mirid species in Canadian greenhouses

Abstract: Omnivorous predatory mirids in genera Dicyphus and Nesidiocoris are variably used as biological control agents (BCAs) in greenhouse integrated pest management (IPM) systems. In Canada, the native Dicyphus hesperus is commercially available for release as a BCA, whereas the adventive Nesidiocoris tenuis has recently been detected in Ontario and is
considered a pest. Although N. tenuis exhibits predatory behaviour, its phytophagy can result
in significant crop damage, outweighing its benefits as a BCA. The coexistence of multiple
predatory mirid species exploiting the same resources creates the potential for intraguild
predation (IGP), which may influence predator population dynamics, spatial distribution, and the efficacy of biological control programs. This study evaluated the direction and strength of IGP among two native and one invasive mirid species D. hesperus, D. famelicus, and N. tenuis. Intraguild predation by a single adult predator and three IG prey nymphs was assessed over multiple 24-h lab assays. Overall, IGP was low, with significant levels observed for D. famelicus preying upon D. hesperus. These assays provide key insights into the strength and direction of IGP amongst native and non-native mirids that may be present in North American greenhouses which will inform development of future biological control programs.