The use of low temperatures and ice-nucleating bacteria against stored-product insect pests
1995
Mignon, J. | Haubruge, E. | Gaspar, C. (Faculte Universitaire des Sciences Agronomiques, Gembloux (Belgium). Unite de Zoologie Generale et Appliquee)
Cold temperatures have been used for many years to control populations of stored-product insects. The aim of aeration was primarily to cool down the grain to prevent its deterioration by reducing the number of insects without eliminating the whole population. The present study was undertaken to determine the survival at low temperature of non-cold-acclimated and cold- acclimated insects, and to evaluate the potential of using the ice-nucleating-active bacteria Pseudomonas syringae to increase the susceptibility of stored-product insects to cold treatments. We have choose to work with the granary weevil Sitophilus granarius (L.) and the saw-toothed grain beetle Oryzaephilus surinamensis (L.). They are both the most frequent stored-grain pests in Belgium. Considering both species, S. granarius adults were more cold-hardy than O. surinamensis, but O. surinamensis adults compensated their cold-sensibility by a great ability to acclimate. S. granarius is able to survive the winter in Belgium because of its cold-hardiness, and O. surinamensis too because of its ability to acclimate to low temperatures. Application of 100 or 1000 ppm of P. syringae in wheat increased the mortality of the two species tested at -10 degrees C (24 h exposure). In the saw-toothed grain beede, all adults died after treatment with 100 ppm, whereas nearly all granary weevils died to 1000 ppm. Different ways to increase the ice-nucleating activity of P. syringae are considered.
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