Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2007
Publication Date: 6/1/2008
Citation: Chanbang, Y., Arthur, F.H., Wilde, G.E., Throne, J.E. 2008. Hull characteristics as related to susceptibility of different varieties of rough rice to Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). Journal of Stored Products Research. 44(3): 205-212. Doi: http://dx.doi.org/10.1016/j.jspr.2007.10.003. Interpretive Summary: The hull of rough rice may offer some protection from the lesser grain borer, a major internal pest of stored grains, because this insect lays an egg on the kernel, and the young larvae must hatch and enter the hull to feed on the kernel. We exposed young larvae of the lesser grain borer on 28 different rice varieties, determined the percentage of solid versus split and cracked hulls, and thickness of the hull. More progeny were produced on rice varieties with higher percentages of cracked hulls and on those varieties with thinner versus thick hulls. Specific varieties were identified as susceptible or tolerant based on the hull characteristics.
Technical Abstract: Rhyzopertha dominica (F.), an important pest of stored grains, causes economic damage to rough rice through physical damage to the kernel, resulting in reductions in grain quality. In this test, 28 varieties of commercial rough rice, 10 long-grain varieties, 11 medium-grain varieties, and 7 short-grain varieties, were examined for solid, split and cracked hulls, hull thickness, and adult emergence from neonate R. dominica introduced on each individual variety. The percentage of solid hulls ranged from 55.5 ± 1.0 on Koshihikari variety to 92.8 ± 1.0% on Akita variety, and the percentage of cracked and split hulls were correlated with increased susceptibility. The Dobie index for progeny production showed Wells, Jupiter, Pirogue, and Bengal varieties (Dobie indices of 1.1 ± 0.6, 1.2 ± 0.4, 1.5 ± 0.2, and 1.6 ± 0.3, respectively) as tolerant to R. dominica, while Rico, Francis, Jefferson, and Dellmati varieties were susceptible (higher Dobie indices of 3.8 ± 2.1. 3.8 ± 0.2, 3.7 ± 0.2, and 3.7 ± 0.2, respectively). The hull thickness of rough rice varied among varieties, but the tolerant varieties appeared to have thicker hulls than the susceptible varieties. There was no difference among rice types (long-, medium-, or short-grain) regarding tolerance or susceptibility to R. dominica.