ECOLOGY, GENOMICS, AND MANAGEMENT OF STORED PRODUCT INSECTS
Location: Stored Product Insect Research Unit
Title: Impact of Rhyzopertha dominica (F.) on quality parameters of milled rice
Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2011
Publication Date: January 1, 2012
Citation: Arthur, F.H., Ondier, G.O., Siebenmorgen, T.J. 2012. Impact of Rhyzopertha dominica (F.) on quality parameters of milled rice. Journal of Stored Products Research. 48(1): 137-142. doi: http://dx.doi.org/10.1016/jspr.2011.10.010.
Interpretive Summary: The lesser grain borer is a major pest of stored rough rice, but there are only a few recent studies that have assessed susceptibility of different rice cultivars to this insect. In this test, adult lesser grain borers were allowed to feed and breed for one week on Francis and Wells cultivars rough rice, two common commercial cultivars, harvested in two different crop years at moderate and low moisture contents. Progeny production was consistently greater in Francis than in Wells, which resulted in reduced rice milling yield and reduced head rice yield in Francis cultivar rice. Techniques were also described that could be used to further assess susceptibility of different rice cultivars to the lesser grain borer.
The impact of Rhyzopertha dominica ([F.), the lesser grain borer, on milling quality of Francis and Wells cultivars was assessed for the 2007 and 2008 crop years by infesting 200-g rough rice samples harvested at moderate and low moisture contents with 0, 10, 25, 50, and 100 parental adult insects, which were removed after one week. The samples were incubated for 7 weeks at either 27 or 32°C and 60% relative humidity to determine progeny production and feeding damage (insect frass), and subsequently the amount of whole rice and % head rice yield (HRY) obtained from a 150-g subsample of the original 200-g sample. Progeny production from each parental density level was variable on each variety at each temperature; hence the parental density level was not a good determinant to use for milling quality assessments. The number of progeny was positively correlated with feeding damage, which in turn was negatively correlated with milled rice yield and % HRY. For both years, more progeny production and feeding damage occurred in Francis versus Wells for each of the harvest moisture contents, which led to lower quantities of milled rice and reduced HRY. Results show differential susceptibility of Francis and Wells cultivars to R. dominica, and also provide new methodologies for evaluating effects of R. dominica infestation on rice milling quality.