The effects of temperature and rice fractions on red flour beetle (Tribolium castaneum) development

The red flour beetle (Tribolium castaneum Herbst) is a globally distributed secondary pest of stored grains and is the primary pest in rice mills. During the process of milling rice, many different rice fractions are produced as the hulls and bran layers are removed to produce white rice. The objective of this study was to determine how red flour beetles develop on various rice fractions and temperatures. Beetles were exposed to brown rice, rice bran, milled whole rice, milled broken rice, and rice flour at 22, 27, 32, and 37°C. The developmental times, survival and elytra lengths were measured. For all temperatures and fractions, there was over 50% adult development from the neonate stage. As temperature increased for all fractions, development time decreased; however, there was no significant difference between 32 and 37°C. The beetles grew larger on rice bran. The results of this study will provide information on where red flour beetles are most likely to colonize in mills based on the preferred milling fractions and will identify where to target monitoring and control efforts.