VULNERABILITY OF COMMON WHEAT CULTIVARS TO MAJOR STORED-PRODUCT BEETLES

Vulnerability of seven common wheat cultivars to nine major species of stored-product beetles was determined in two experiments by measuring multiplication rates on whole and crushed seeds at 30 °C and 70% relative humidity for 12 wk. Susceptibility of a cultivar to an insect was assumed to be proportional to the multiplication of that insect. Vulnerability of cultivars varied considerably depending on the insect species infesting the seed. Whole seeds generally were less susceptible to insects than crushed seeds, except for Sitophilus spp. and Rhyzopertha dominica. In the first exploratory experiment using three cultivars and nine insect species, whole seeds of Norstar, HY320 and Neepawa were least susceptible to Tribolium audax and Oryzaephilus mercator, and most susceptible to Sitophilus oryzae and R. dominica. In the second experiment using six cultivars and six insect species, susceptibility of whole seeds appeared to be related to the kernel hardness of a cultivar with Glenlea and Neepawa being least susceptible to infestation by Cryptolestes ferrugineus, O. surinamensis, T. castaneum and T. confusum. Kernel hardness either did not affect or slightly affected the multiplication rates of Sitophilus spp. and R. dominica. Generally, soft wheat cultivars grown in western Canada are at a greater risk of postharvest insect damage than are the hard red spring cultivars; HY320 which is intermediate in kernel hardness may be prone to greater insect infestation.Key words: Wheat, Norstar, HY320, stored-product beetles