Abstract: Species of soil predatory mites feed on a diverse diet making them excellentcandidates for conservation biocontrol programs. Free living nematodes (FLNs) are commonlyfound in soils and serve as prey for many soil predatory mites (SPMs). Some species must feedon nematodes to lay eggs and others will need them to complete immature development.Surprisingly, as far as we know, FLNs have never been used as alternative prey to enhance theefficacy of soil predatory mites for conservation biological control. Here, we present results oftwo case studies where we provisioned the FLNs Rhabditella axei as complementary prey forpredatory mites. In the first study, we used SPMs Macrocheles embersoni for housefly controland in the second, Stratiolaelaps scimitus for the control of the root knot nematode Meloidogyneincognita. In both systems, complementing the diet of predatory mites with FLNs resulted inhigher predator abundance and better biological control, compared to the negative control andthe release of predators without FLNs. Future research will focus on evaluating soilamendments to enhance the abundance of FLNs and predatory mites in protected and outdoorcropping systems for the conservation biological control of soil pests.