Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2014
Publication Date: 6/1/2014
Citation: Yokoyama, V.Y. 2014. Multiple quarantine treatment using bale compression and a three day fumigation to control Hessian fly (Diptera: Cecidomyiidae) in exported hay. Journal of Economic Entomology. 107:981-986. Interpretive Summary: Hessian fly has been a pest in US wheat since the Revolutionary War, and certain Asia-Pacific nations are concerned that the insect may be accidentally introduced into their countries through hay imported for animal feed. Although the pest is unlikely to be found in high quality domestic hay, a quarantine treatment is needed to access some foreign markets. A new treatment method was developed and confirmed in commercial tests to control Hessian fly. The treatment is unique because it has a short application time and is based on rapid compression of hay in modern compressors to make export size bales. Bale compression is then followed by a three-day fumigation which is much shorter than the previous seven-day treatment. The new procedure allows faster movement of export bales from hay processing plants to domestic ports for ocean freight into foreign markets. Expedited handling of premium quality US hay should lead to increases in the volume of hay exports from the western states currently valued near a billion dollars in sales and freight revenues.
Technical Abstract: A multiple quarantine treatment was developed to control Hessian fly puparia, Mayetiola destructor (Say), the stage of regulatory concern in exported hay. In a commercial test using 51,589 puparia, no insects survived to the adult stage after exposure to bale compression at 137 kg/cm² and fumigation with 61 g/28.3 m3 hydrogen phosphide for 3 days. The puparia were fumigated in infested wheat seedlings in cloth bags inside compressed timothy bales placed in different locations in three replicate freight containers in a heated building. Fumigant concentrations were 345-522 ppm on day 1, 580-824 ppm on day 2, and 680-861 ppm on day 3. Monitored temperatures were below 20°C in all locations allowing the fumigation temperature to be established at greater than or equal to 20°C or above. Copper detection plate corrosion values were severe inside the freight container doors, and moderate in the middle of bales in all locations, providing visual confirmation of exposure to hydrogen phosphide. Hydrogen phosphide residues in exposed hay bales were found in trace amounts, below the U.S. Environmental Protection Agency tolerance of 0.1 ppm for animal feeds. Timothy hay used in the commercial test is the representative species for all previously exported hay and straw species. The new multiple quarantine treatment is proposed for use with all previously tested bale sizes and wrapper styles for which 3-d fumigation data has been reported, and for bales and wrappers derived from those tested.