A bait trap for monitoring acarid mites (Acari: Acaridae) in agricultural soils

An acarid bait trap constructed from moistened, folded filter paper containing a small quantity of dry yeast was used to monitor the number of Tyrophagus similis and Rhizoglyphus robini in agricultural soils. In laboratory-based evaluations, the trap captured, on average, 88% (capture rate=no. of captured/no. of released×100(%)) of the T. similis and 65% of the R. robini adults by 3 d after application of the trap, though the capture rate was lower for the immature stages of both species. Field trials were carried out to monitor T. similis numbers in a spinach greenhouse soil and R. robini numbers in a Welsh onion field soil using both the bait trap and the Tullgren funnel. Population trends for T. similis were similar in both trials, but T. similis numbers were consistently and significantly higher in the bait trap than in the Tullgren funnel. Numbers of R. robini obtained from the soil did not differ significantly between the two methods. These results suggest that efficient monitoring of acarids in the genera Tyrophagus and Rhizoglyphus is possible using the acarid bait trap.