Postharvest rice losses, a problem which is worsening as more and more countries achieve rice self-sufficiency, can be reduced by growing rice varieties resistant to rice storage insects. This report reviews the current state of research on a still largely neglected approach to developing resistant rice varieties — namely, by correlating varietal resistance with the grain”s physicochemical properties. Research has shown that breeding characteristics such as intact tight hulls, a high degree of grain hardness, the presence of bran layers, high amylose content, high endosperm starch gelatinization temperature, low oil content, small and lightweight grain proportions, and low moisture content contribute to impeding a variety of storage insects — the rice weevil, the lesser grain borer, the Angoumois grain moth, the confused flour beetle, the Indian mill moth, the red flour beetle, and the almond moth. Processing techniques such as a high degree of milling and parboiling or heating the wet grain at 100 degrees Centigrade also impede insect infestation. The report briefly analyzes the resistant characteristics of several varieties developed for U.S. production. The report suggests future research be conducted on the interrelationship between grain hardness and grain quality (as measured by protein and amylose contents, alkali spreading value, and gel consistency) and that varietal resistance to major storage insects be investigated using pairs of sister lines differing in the property in question. A 51-item bibliography (1946-80) is appended.
