Estimating Monitoring Trap Plume Reach and Trapping Area for Drosophila suzukii (Diptera: Drosophilidae) in Michigan Tart Cherry

Central-monitoring trap, multiple point release-recapture experiments were used to interpret Drosophila suzukii (Diptera: Drosophilidae) catch in a monitoring trap baited with a Scentry Biologicals commercial D. suzukii lure deployed in Michigan tart cherry orchards. The plume reach was found to be short (<3 m), while the maximum dispersive distance for 95% of the released D. suzukii was projected to be ca. 90 m, so as to yield a trapping area of 2.7 ha. These data were consistent across two growing seasons and provide the first information about the dispersal distance and monitoring trap efficacy in a fruit crop setting for D. suzukii. Catch data per single monitoring trap can now be used to estimate absolute pest density in cherries. Alarmingly, catching one D. suzukii in a monitoring trap translates to approximately 192 D. suzukii per trapping area of 2.7 ha (26 per acre). Thus, by the time D. suzukii catch becomes detectable, it is very probable that the population is already above the tolerable damage threshold, suggesting control measures should immediately be taken if the fruit is in a vulnerable stage. Caution should be taken when extrapolating these results from cherry because the measured values may differ in other crop systems.