Optimizing postharvest methyl bromide treatments to control spotted wing drosophila, Drosophila suzukii, in sweet cherries from Western USA

Methyl bromide (MB) chamber fumigations were evaluated for postharvest control of spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), in fresh sweet cherry exports from Western USA. Sweet cherries were infested with SWD, incubated to maximize numbers of the most MB-tolerant specimens (ca. 60 to 108-h old at fumigation, 88% 3rd & 2nd instars), buried amongst uninfested fruit in bins consistent with commercial practice, cooled to an average pulp temperature ≥ 8.3 °C, and then fumigated in a chamber. Treatment efficacy was diagnosed by the percentage of survivors emerging as adults from fumigated cherries relative to that from non-fumigated control cherries. A kinetic model of sorption was developed based on the measurement of MB and how calculated exposures varied across the fumigation trials. The model describes how to manipulate the applied MB dose, fumigation duration, and the load factor so that the resultant exposure is adequate for SWD control across various pulp temperatures when cherries are fumigated in wooden versus plastic bins. Results are discussed in the context of graduation toward optimized quarantine fumigation schedules for control of SWD, which will promote more strategic technical and economic Quarantine Pre-shipment (QPS) use of MB. [Display omitted] •Postharvest methyl bromide fumigation provided probit 9-level control of D. suzukii.•Required fumigation parameters were identified at treatment temperature ≥ 8.3 °C.•Results promote a more strategic technical and economic QPS use of methyl bromide.