Alternatives to methyl bromide as fumigants against arthropod pests infesting southern dried-cured ham facilities in the US

Fumigation with methyl bromide (MB) has been a long established and effective method for controlling the pests infesting southern dry-cured ham in the USA. MB has been identified as an ozone-depleting chemical and its use is being restricted in accordance with an international agreement, and a more rapid alternative is desirable. This study compares the efficacy of fumigants including phosphine, sulfuryl fluoride (SF) as an alternative to MB against two major key arthropod pests of dry-cured ham under laboratory conditions. Laboratory bioassay showed that phosphine was more effective for controlling both red-legged ham beetle Necrobia rufipes DeGeer and ham mite Tyrophagus putrescentiae Schrank than MB. Eggs of both species were found to be highly tolerant to phosphine and MB at 48h exposure than other stages. A complete control was achieved for the both species with a dose level 0.85 and 4.0 g/m³ of phosphine and MB respectively. SF yielded 100% control of all the stages of N. rufipes by 8 g/m³ except eggs which required the doses from 20.88 to 24.72 g/m³ for inhibiting 100% hatchability. The ham mite showed high tolerance to SF being able to survive concentration-time products in excess of EPA standard label limit 1500 g.h/m³ over a 48h exposure at 23ºC.