Differential preference of grain of landrace and commercial rice genotypes to Sitophilus oryzae (L.) (Coleoptera: Curculionidae) attack

Abstract

The rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is one of the most damaging pests to stored cereal grains worldwide. The current study aimed to clarify the relationship between S. oryzae development and the governing physicochemical grain properties. Laboratory experiments were conducted to determine the grain preference of various landrace and commercial rice genotypes to rice weevil. S. oryzae, findings divulged the low rates of adult emergence, low rates of grain consumption and high rates of mortality in the grain of rice varieties, HUR-3022 and Nagina-22. Conversely, S. oryzae adult emergence and grain consumption were found to be high in the grain of Swarna, Sathi, and Pusa basmati-1. Interestingly, the morphological and biochemical composition of the grain was the most important factor in determining resistant or preferred rice varieties to S. oryzae. Among the various physical characteristics investigated, grain hardness was found to have a significant and negative correlation with alive insect, grain weight loss, and preference index. On the other hand, protein and other biochemical grain characteristics were found to have a positive correlation with insect emergence, weight loss, and preference index. In particular, amylose (a key grain component) was found to have a negative correlation with weight loss and insect emergence. The findings of this study suggest that screening of different rice genotypes, for determining grain preference, may be a more viable option to minimize the grain losses during storage caused by S. oryzae. Moreover, the findings of present study could also help to formulate the breeding programs aimed at developing cultivars resistant to this notorious pest.