The suitability of wheat grain and grain of three less common cereals as hosts for the rice weevil (Sitophilus oryzae [L.]) (Coleoptera: Curculionidae)

Abstract

The aim of the present study was to test the suitability of different grain commodities, i.e., common wheat (Triticum aestivum), millet (Panicum miliaceum), spelt (Triticum aestivum ssp. spelta), and buckwheat (Fagopyrum esculentum) as hosts for the rice weevil (Sitophilus oryzae). We monitored weevil mortality and progeny emergence. Two different amounts of grains (50 g and 100 g) were applied. The experimental units were stored at three temperatures (15, 20, and 25 °C) and at two relative humidities (RHs) (55 and 75%), for a total of six combinations. Mortality was assessed on the 7th, 14th and 21st days after exposure. After 56 days, we determined progeny emergence. We determined that weevil mortality was correlated to temperature, RH, grain commodity, grain quantity and exposure duration. In general, mortality counts were higher at lower grain quantities. The mortality and progeny emergence were highest in wheat grain, since wheat grain is the most suitable host. Progeny production (emergence) was highest at 25 °C. Only a few individuals emerged from buckwheat and millet.