On-Site Confirmatory Test, Film Wrapped Bales, and Shipping Conditions of a Multiple Quarantine Treatment to Control Hessian Fly (Diptera: Cecidomyiidae) in Compressed Hay

Abstract

No Hessian fly, Mayetiola destructor (Say), adults emerged from infested wheat seedlings (15,377 total puparia) in an on-site confirmatory test when exposed to compression and fumigation (60 g/28.3 m3 aluminum phosphide) in hay bales in 5 different locations in a freight container. Mean temperatures in the freight container ranged from 15.4 to 19.6°C during the 7-d fumigation in a heated building. Hydrogen phosphide residues were below the U.S. Environmental Protection Agency tolerance of 0.1 parts per million in animal feeds 1 and 3 d after aeration. The successful completion of the on-site confirmatory test allowed approval in December 1996, of timothy, alfalfa, oat, Sudan grass, and Bermuda grass hays for export to Japan. Hydrogen phosphide concentrations in film wrapped and unwrapped units of compressed timothy hay were not significantly different throughout the 7-d fumigation period of the multiple quarantine treatment. The data showed that use of film-wrapped units of compressed hay bales would not diminish the efficacy of the treatment and was approved by regulatory agencies in December 1997. The highest bale temperatures in freight containers of either timothy, alfalfa, Sudan grass, or Bermuda grass hays were recorded on days 1–3 (mean ± SE) (range of 15.87 ± 0.02°C to 27.44 ± 0.02°C) during ocean freight from Seattle, WA, to Nagoya, Japan. Lowest temperatures enroute were recorded on days 7–9 (range, of 6.75 ± 0.03°C to 9.59 ± 0.02°C). The range of the mean percentage relative humidity (mean ± SE) was 31.7–60.0 for all species of hay at 3-d intervals during 12 d of ocean freight. Mean bale temperatures and relative humidities during ocean freight were in general lower than optimum for growth and development of Hessian fly.