Monday, December 10, 2007 - 8:17 AM

Induced resistance in rice (Oryza sativa) to the rice water weevil (Lissorhoptrus oryzophilus) using jasmonic acid

Jason C. Hamm, jhamm@agcenter.lsu.edu1, Michael J. Stout, mstout@agcenter.lsu.edu2, Maria R. Riggio, rriggio@agcenter.lsu.edu1, and Sam Pourian, spouri1@lsu.edu1. (1) Louisiana State University, 404 Life Sciences Bldg, Baton Rouge, LA, (2) Louisiana State University Agricultural Center, 404 Life Sciences Bldg, Baton Rouge, LA

The rice water weevil, Lissorhoptrus oryzophilus (Kuschel), is the most destructive early-season insect pest of rice in Louisiana. Adults feed on leaves, leaving longitudinal scars, while larvae migrate to roots in order to feed. The major physiological effects of root pruning appear to be a reduction in tillering of infested plants and a reduction in panicle density at harvest. On average, yield losses of 10% are encountered, and losses exceeding 30% are not uncommon. In addition, this insect has been accidentally introduced into some of the major rice-producing regions of Asia and poses a global threat to rice production. Jasmonic acid (JA) is a plant hormone that mediates plant responses to insect herbivory in many plants, and exogenous applications of JA have been used to induce resistance in several plant species. Treating rice plants at the two-three leaf stage with exogenous applications of JA reduced the number of eggs oviposited as well as densities of first and late instar larvae. Similar experiments were undertaken in field plots using two different varieties, Jasmine and Rosemont. Our field data did not show any significant effect of JA on L. oryzophilus oviposition or larval densities; however, our data indicates a significant variety effect.

Species 1: Coleoptera Curculionidea Lissorhoptrus oryzophilus (rice water weevil)
Species 2: Lepidoptera Pyralidae Diatraea saccharalis (sugarcane borer)