Utilizing low oxygen to mitigate resistance of stored product insects to phosphine.

ABSTRACT

BACKGROUND: Data are provided on the utilization of modified atmospheres, at a commercial scale, against stored product insect populations that are resistant to phosphine. The method is evaluated on different populations of two major stored-product beetle species, Rhyzopertha dominica and Oryzaephilus surinamensis. The trials were carried out in commercial facilities, in which nitrogen was introduced through an embedded nitrogen generator. Each chamber contained three or four pallets of either currants or herbs. A computational model was developed to evaluate the nitrogen concentration. RESULTS: In most trials, 100% mortality was recorded for both beetle species and all populations, regardless of the temperature and exposure intervals tested. Control progeny production ranged between 20 and 45 adults per vial for R. dominica, and 29 and 27 adults per vial for O. surinamensis. Simulation results reveal that nitrogen can easily penetrate the currants, and its concentration is uniform (differences are below 1.5%) across the pallet. Additionally, the simulation model revealed that lower temperatures do not have an impact on the nitrogen concentration profiles. CONCLUSIONS: The modified atmosphere applications evaluated here were proved to be effective for all populations, regardless of the level of resistance to phosphine, and any survival could be attributed to the short exposure intervals. Modified atmosphere applications can be effective at a considerably short exposure interval, even at 2.5 days, which is an incontestable advantage for the use of this method against insects, at exposures comparable with those of commercial fumigations. © 2022 Society of Chemical Industry.