Author
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Plarre, Ruediger |
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REICHMUTH, CHRISTOPH - FED BIO RES CTR-GERMANY |
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Submitted to: Controlled Atmosphere & Fumigation in Stored Products International Conference
Publication Type: Proceedings Publication Acceptance Date: 4/26/1996 Publication Date: N/A Citation: N/A Interpretive Summary: The use of fumigants to control insects in stored products is extremely important because they act fast and penetrate the infested commodities entirely thus also controlling hidden infestations inside grain kernels. Methyl bromide is a widely used fumigant especially for quarantine purposes, but because of its ozone depleting potential it is expected to be phased out during the next decade. Alternative fumigants are needed, and carbonyl sulfide might be one candidate. Studies were undertaken to determine the potential of carbonyl sulfide to control the granary weevil. This pest insect very commonly infests stored grain in moderate climate zones and develops inside grain kernels. Therefore it is very difficult to control by other means than fumigation. This is the first time that dosage response data were collected using this potential new fumigant on the granary weevil. Storage fungi, which are very often associated with insect infestation, were also treated with the new fumigant. Toxic dosages to the insects did not control fungal growth, but the developmental time was slowed down considerably. However, by controlling insect infestation, fungal development can be prevented. The study shows that carbonyl sulfide has the potential to replace methyl bromide as a fumigant of stored grain, but further research is necessary before it can be recommended. Technical Abstract: All life stages of Sitophilus granarius, as well as the fungi Fusarium avenaceum and Fusarium culmorum, were tested for their susceptibility to different times of exposure and concentrations of carbonyl sulfide (COS) at 20 degrees C and 70% R.H. Complete kill of S. granarius occurred at concentrations of 18 gm-3 COS for 120 hours or 32 gm-3 COS for 72 hours. The eggs were most tolerant to the toxic gas, followed by pupae and adults. Larval stages were most susceptible to the fumigant. Sublethal dosages prolonged the developmental periods of the immature life stages. Sublethal dosages on S. granarius caused growth inhibition in F. avenaceum and F. culmorum, though the fungi recovered fully after treatment. In the presence of high relative humidity COS was presumably degraded partly to H2S which caused corrosion on copper. Carbonyl sulfide being a possible alternative to methyl bromide is discussed. |
