Trials of application of phosphine gas as methyl bromide (MB)
alternative for fumigation of stored grain during storage were carried out from
December 1999 until July 2000 in concrete silos of the General Company for
Silos and Storage. For treatment, imported wheat grains were transferred from
the storage bins into the fumigation cells of the silo as usually practised with
methyl bromide (MB).
Two phosphine formulations, namely Detia DEGESCH — Magloxin
Tablets and Detia Gas Ex Bags — forte (small bags, 9 g. each) were used al the
following dosage: -
3 phosphine tablets per one m3 and one small bag per one m3 al varying
exposure periods. Trials were conducted during winter and summer Limes. Grain
temperature was in range from 12-20°C during winter and from 22-27°C in
summer, The relative humidity of air was between 50-60% inside the fumigation
cells of the silo.
The efficiency of the previously mentioned phosphine formulations was
tested against the adults and inunature stages of the followiig important storage
insects in Egypt:
Rice weevil, Sitophilus orvzae (L.); lesser grain borer, Rhizopertha
dominica (F) and red flour beetle, Triholium caslaneuin (Herbst.) as well as
active and diapausing larvae of Khapra beetle. Trogoderma granarium Evens.
The obtained results showed that at the dosage used, the two-phosphine
formulations were effective against the adults and immature stages of the tested
insect species. However, the bio-toxicity of the gas was temperature and exposure
period dependent. It was found that at 16—20°C grain temperatures, an exposure
period of 7 days was required for complete mortality and this period was
prolonged to 10 days when the temperature of the grain fell to 12—16°C.
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