Stored rice varietal resistance towards Sitophilus oryzae

Previous research has demonstrated that varieties of rice are differentially susceptible to stored rice pests, but modern varieties are lacking evaluation. Thirteen varieties of rice, Oryzae sativa (L.), were tested for their susceptibility to the rice weevil, Sitophilus oryzae (L.). Sitophilus oryzae adults were placed into vials containing one of 13 USA commercial rice varieties. Adult damage, larval damage, days to eclosion, total progeny, and progeny mass were recorded over a period of six weeks. Subsequently, varietal mixes of the resistant and susceptible varieties were evaluated for associational resistance or susceptibility using the same methodology. Rice variety impacted adult damage, larval damage, progeny counts, progeny mass, and development time. The rice variety most susceptible to adult damage had 11-fold greater damage than the rice variety most resistant to adults. Similarly, the rice variety most susceptible to larval damage received 10-fold more damage than the most resistant. Progeny had the shortest development time and greatest adult mass feeding on high protein, low-glycemic rice variety, Frontière. Varietal mixes often resulted in associational susceptibility, where mixes of two rice varieties resulted in damage equal to or greater than that of the most susceptible variety in the mix. Blends created similar changes in the numbers of progeny, progeny mass, and development time. These results demonstrate the importance of stored rice varietal susceptibility, blend susceptibility, and their impact on stored rice pest management.