Free living nematodes as alternative prey for soil predatory mites: An interdisciplinary case study of conservation biological control

•In small arenas over 8 days, offering nematodes reduced predation on L1 fly larvae.•Similarly, in large arenas in week 3 providing nematodes increased fly emergence.•In contrast, in week 4 nematodes supplementation dramatically reduced fly emergence.•Predatory mite abundance in week 4 was 3 times higher with nematode provisioning.•Temporal and spatial scales determined the biocontrol impact of nematode provisioning.