Biological Study on the Granary Weevil, Sitophilus granarius (L.) on Stored Wheat During the Different Seasons with Special Reference to Its Host Preference

This research was conducted to study the biology of Sitophilus granarius on stored wheat and to explore the preference host to the granary weevil. The laboratory experiments were carried out at the Department of Plant Protection, Faculty of Agriculture, Minia University, during the weather-diverse seasons of 2022-2023. The different developmental stages of S. granarius differed according to seasonal differencing. However, the highest durations of various stages of this pest were registered during the winter followed by autumn, but the shortest period was recorded during the summer. These results proved the significant impact that environmental factors, particularly those that change with seasonal fluctuations have on the insect's developmental cycle. It could be concluded that the durations of different stages of this weevil were shorter as the temperature increased.The host preference for this pest was studied on seven different hosts viz ., wheat, polished rice, barley, maize, sorghum, rough rice and oats under constant temperature (25ºc) and laboratory conditions for two successive generations. The results revealed that the maximum weight loss percentage and the highest number of adult emergence (23.73, 23.63%) and (53.75, 75.25 adults) were recorded on the wheat host for 1 st and 2 nd generations, respectively. In contrast, the minimum preference for polished rice (1.40,1.10%) and (0.00, 0.00 adults) was recorded under the constant temperature of 25 ºc and laboratory conditions, respectively. The ranking of host preference or suitability of different cereals was recorded as wheat ˃ sorghum ˃ rough rice ˃ oats ˃ maize ˃ barley ˃ polished rice.