Location: Stored Product Insect Research Unit
Title: Lesser grain borers, Rhyzopertha dominica, select rough rice kernels with cracked hulls for infestation Authors
Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2011
Publication Date: March 15, 2012
Citation: Kavallieratos, N.G., Athanassiou, C.G., Arthur, F.H., Throne, J.E. 2012. Lesser grain borers, Rhyzopertha dominica, select rough rice kernels with cracked hulls for infestation. Journal of Insect Science. 12:38. Available online: insectscience.org/12.38. Interpretive Summary: Lesser grain borers are serious pests of stored rice throughout the world. Varieties of rice vary in their resistance to insects, and resistance may be related to cracks in the hull of the rice kernel. Lesser grain borers lay their eggs loose in the mass of rice kernels, and young larvae search out and bore into a rice kernel, where they complete development. Thus, kernels with cracked hulls may be selected by females for egg laying or they may be selected by larvae because they may be easier to enter. We showed that more progeny emerged from kernels with cracked hulls when these kernels were mixed in with intact rice kernels, but some progeny did emerge from intact kernels. Thus, using grain handling methods that reduce cracked hulls in rice would be expected to reduce insect damage to rice in storage.
Technical Abstract: Tests were conducted to determine whether differing amounts of kernels with cracked hulls (0, 5, 10, and 20%) mixed with intact kernels affected progeny production of the lesser grain borer, Rhyzopertha dominica, in two rough rice varieties, Francis and Wells. Wells had been previously classified as tolerant to R. dominica, while variety Francis was classified as moderately susceptible. There were few F1 progeny produced in Wells regardless of the percentage of kernels with cracked hulls, few of the kernels with cracked hulls had emergence holes, and little frass was produced from feeding damage. At the levels of 10 and 20% kernels with cracked hulls, progeny production, number of emergence holes in kernels with cracked hulls, and the amount of frass was greater in Francis than in Wells. The proportion of progeny emerging from kernels with cracked hulls increased as the proportion of kernels with cracked hulls increased. The results suggest that the presence and level of hull damage may affect progeny production by R. dominica on different rice varieties.