Attack rate and prey preference of Lasioseius subterraneous and Protogamasellus mica on four nematode species.

Plant parasitic nematodes are common and important global pests, causing over US$150 billion in crop losses across the agricultural sector worldwide. Meloidogyne javanica and Pratylenchus zeae are two of the most damaging plant-parasitic nematodes and there are limited options for their control. We evaluated the potential of a large (Lasioseius subterraneous) and a small (Protogamasellus mica) mesostigmatan mite as biological control agents of plant-parasitic nematodes. We tested the attack rate and reproductive potential of these two mite species on four nematode species: M. javanica (eggs), Pra. zeae (adults) and two microbivorous nematodes, Mesorhabditis sp. and Aphelenchus avenae (adults for both species). Each mite/nematode combination (1 mite:100 nematodes) was tested in six replicate arenas. In a separate trial, each mite species was presented with 50 A. avenae and 50 Pra. zeae in the same arena to determine prey preference. Both mite species significantly reduced the abundance of all nematode species used in the trials when compared to nematode-only controls. Lasioseius subterraneous consumed all available M. javanica eggs within 72 h. The larger mite had a significantly higher overall attack rate than the smaller mite, each consuming an average of 96 and 72 nematodes, respectively, within 72 h. However, both mites had a similar reproductive rate. Protogamasellus mica displayed a positive preference towards the plant parasitic nematode Pra. zeae over the fungal feeding A. avenae whereas L. subterraneous did not display a prey preference. Our results highlight the potential of these two predators to control plant parasitic nematodes, although further trials under field conditions are needed.