Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 2001
Publication Date: April 20, 2002
Citation: Yokoyama, V.Y., Miller, G.T. 2002. Bale compression and hydrogen phosphide fumigation to control cereal leaf beetle (coleoptera: chrysomelidae) in exported rye straw. Journal of Economic Entomology. Volume(95):513-519. Interpretive Summary: Cereal leaf beetle was recently discovered in certain hay producing areas of Oregon and Washington where it was previously not know to occur. The presence of this pest has jeopardized interstate and foreign exports of hay. Quarantine treatments were developed in response to industry and state regulatory agency requests to ensure that cereal leaf beetle would not be accidentally introduced into areas where it is not found through hay exports. Field research showed that compression of standard bales of rye straw plus a one-day storage period resulted in 100% mortality of cereal leaf beetle larvae and adults. Cereal leaf beetle adults where shown to be sensitive to phosphine fumigation in laboratory tests. A combined treatment of bale compression followed by a 3-d fumigation was confirmed to control cereal leaf beetle in rye straw in large-scale commercial tests. The development of these quarantine treatments to control cereal leaf beetle will prevent interruptions in the export of grass hay to Japan and interstate shipments within the U.S. The annual sales of Oregon grass straw to Asia are over 400,000 tons at a value of $50-60 million.
Technical Abstract: Cereal leaf beetle, Oulema melanopus (L.), larvae and adults were collected in Oreg., Mont. and Wyo. and delivered to a temporary laboratory in Aurora, Oreg. Natural mortality of larvae after transport was 4.0 plus or minus 1.0%. Compression (105 kg per sq. cm) of larvae in standard bales (122 cm long) of rye straw resulted in 100% mortality. Compression of adults in standard bales and storage of the compressed bales (56 cm long) for 1 d in a freight container resulted in 100 % mortality. A KD50 of 102 ppm hydrogen phosphide for 1 h was extrapolated from the probit regression line developed from dose-response data at 21C in basic laboratory tests. The LD50s and LD99s were 163 and 6910 ppm for 2 h exposures and were 18 and 42 ppm for 6 h exposures at 21C. A tested dose of 400 ppm for 24 h at 21C resulted in 100 % mortality of the adults. Larvae (n = 10,560) and adults (n = 18,602) did not survive exposure to bale compression followed by hydrogen phosphide fumigation (60 g per 28.3 cu. m) for 3 d in rye straw loaded in freight containers in large-scale tests. Copper plate corrosion values were 13 and 12, and mean temperatures in different locations in the freight container were 25 and 26C in large-scale tests with the larvae and adults. Hydrogen phosphide concentrations were greater or equal to 400 ppm throughout the 3 d fumigation for larvae and during the first day of fumigation for adults. Cereal leaf beetle can be controlled by a single treatment of bale compression followed by a 1-d storage period or by a fumigation in which 400 ppm hydrogen phosphide is maintained for 1 d at 21C or above. A multiple quarantine treatment of bale compression followed by a 3-d fumigation was confirmed to control cereal leaf beetle in exported rye straw.