1a. Objectives (from AD-416):
Stored-product insect populations are usually controlled by the use of insecticides. However, the development of resistance to several traditional insecticides, in both the U.S. and Europe, necessitates the evaluation of newer compounds and non-toxic methods for control of resistant insect populations. The application of extreme temperatures is one of the solutions suggested. The use of elevated temperatures, known as heat treatment, has been evaluated with success against several species in many commodities. However, there are not many data available for the use of cold treatments for this purpose, despite the fact that there is evidence that this method can be also successful, with no adverse effects on product quality (as is often observed in the case of heat treatment). The basic objective of the present collaboration is to estimate the efficacy of cold treatments against stored-product insects, and the factors that affect its application.
1b. Approach (from AD-416):
Insect populations from the U.S. and Europe will be collected and reared under laboratory conditions. Bioassays will be carried out in order to assess the efficacy of cold treatment at different combinations of temperatures and exposure intervals. The temperatures will be 5, 0, -2, -5, -10, and -20 degrees C, and the exposure intervals will be 2, 4, 8, 24, 48, and 72 h, and 7 d. The tested species will be the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae), the confused flour beetle, Tribolium confusum Jacquelin Du Val (Coleoptera: Tenebrionidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), and the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae). For T. confusum and T. castaneum, all life stages will be tested, while for O. surinamensis adults and larvae and for the other species only adults will be tested.
3. Progress Report:
Preliminary tests were conducted with different life stages of the psocid Liposcelis entomophila and the red flour beetle, Tribolium castaneum, to determine the range of times needed to kill these species at 0 degrees F. Similar preliminary studies will be conducted with other species before initiating full-scale experiments on use of freezing to kill these insect pests.