Potential of the Predatory Mites <i>Gamasellodes lavafesii</i> (Mesostigmata: Ascidae) and <i>Cosmolaelaps mediocuspis</i> (Mesostigmata: Laelapidae) on Different Soil Pests/Parasites and Alternative Prey for Large‐Scale Rearing

ABSTRACT Many species of Mesostigmata soil mites have potential as biological control agents of pests/parasites. This study evaluated the predation potential of two of these species, Gamasellodes lavafesii (Ascidae) and Cosmolaelaps mediocuspis (Laelapidae). The harmful species evaluated as prey were the root‐knot nematode, Meloidogyne javanica (Heteroderidae), the gastrointestinal sheep‐parasitic nematode, Haemonchus contortus (Trichostrongylidae), the bulb mite, Rhizoglyphus columbianus (Astigmata: Acaridae) and the sciarid fly, Bradysia matogrossensis (Diptera: Sciaridae). Additionally, five species were tested as potential alternative food sources for the mass rearing of predators: eggs of Ephestia kuehniella (Lepidoptera: Pyralidae), the mites Glycyphagus destructor (Astigmata: Glycyphagidae), Thyreophagus cracentiseta and Tyrophagus putrescentiae (Astigmata: Acaridae), and the free‐living nematode Rhabditella axei (Rhabditidae). Daily predation rates (by female) between the predators did not differ when M. javanica was offered (≅240–245 second‐stage juveniles). For H. contortus , G. lavafesii exhibited a higher daily predation rate (≅204 third‐stage juveniles), whereas C. mediocuspis showed higher daily consumption of R. columbianus (≅6.1 larvae/nymphs) and B. matogrossensis (≅1.5 larvae). The highest oviposition rate of G. lavafesii (3 eggs/female/day) was observed on M. javanica , while C. mediocuspis laid at most 0.6 eggs/female/day on all evaluated prey. For large‐scale rearing, R. axei provided the best oviposition rate for G. lavafesii (8 eggs/female/day), whereas the highest rate for C. mediocuspis was obtained on E. kuehniella eggs (1.3 eggs/female/day). These findings will provide valuable insights for developing new biological agents for harmful organisms that spend part of their life cycle in the soil.