A real world examination of sulfuryl fluoride as a replacement for methyl bromide in midwestern U.S. flour mills

As a result of the Montreal Protocol, methyl bromide, a major fumigant for the food industry, is facing a mandatory 100% production and import phase out. Millers, food processors and fumigators are seeking replacements. Sulfuryl fluoride is one replacement strategy that was recently labeled for the food market. This paper summarizes research that is underway to compare the effectiveness of methyl bromide and sulfuryl fluoride under real world conditions. Since 2005, five methyl bromide and nine sulfuryl fluoride fumigations have been completed in four U.S. flour mills. All life stages (eggs, larvae, pupae, and adults) of two major pest species, Indianmeal moth, Plodia interpunctella (L) and red flour beetle, Tribolium castaneum (Herbst) were used in bioassays exposed during fumigations. Insect monitoring (moth flight traps and flour beetle dome traps) was conducted before and after the fumigations to determine the existing pests population and rebound rates. Bioassay results indicate 100% mortality of larval and adult stages of both species for both fumigants. More than 99% of RFB and 100% of IMM pupae died when exposed to either fumigant. Of the few exposed eggs that hatched, the majority died before the adult stage. Insect populations were usually significantly lower right after fumigation but could increase to pre-population level within 2-8 weeks depending on the facility, sanitation, and population pressure.