Interactions between graminaceous weed and insect pests of rice and between management practices for these pests were investigated. Studies were conducted to examine preference and performance of rice water weevil, <i>Lissorhoptrus oryzophilus</i> Kuschel, on several weeds commonly found in rice fields. Several weeds were more preferred than rice, and larvae were present on several dicotyledonous weeds, suggesting the host range of <i>L. oryzophilus</i> is broader than previously thought.
Effects of the presence of barnyardgrass, (<i>Echinochloa crus-galli</i> Beauv.), on rice stink bugs, <i>Oebalus pugnax</i> F., and <i>L. oryzophilus</i> populations in rice fields were investigated. Presence of barnyardgrass and the synchrony of barnyardgrass seed heads and rice panicles influenced <i>O. pugnax</i> densities on rice. Barnyardgrass served as a trap crop or as a source of infestation of <i>O. pugnax</i> depending on the developmental stage of barnyardgrass relative that of rice. Presence of barnyardgrass had little impact on <i>L. oryzophilus</i> . Similar studies conducted with borers and Amazon sprangletop, <i>Leptochloa panicoides</i> (Presl.) Hitchc. revealed that injury to rice was greater in weedy plots of rice than in pure plots of rice.
Studies were conducted to determine how density of weeds affected <i>O. pugnax</i> populations and how weeds and <i>O. pugnax</i> combined to reduce grain yield and quality. Numbers of <i>O. pugnax</i> and percentages of filled seeds, pecky rice, and broken kernels increased as weed density increased. Increases were less severe in insecticide-treated than non-treated plots. However, yield losses from weeds and insects were not significantly greater than from weeds alone.
Preference and performance of <i>L. oryzophilus</i> on herbicide-treated and non-treated glufosinate-tolerant rice were investigated. Glufosinate applications on glufosinate-tolerant rice reduced weevil oviposition by 30% and reduced larval densities by 20% compared to non-treated glufosinate-tolerant rice. Glufosinate was not toxic to <i>L. oryzophilus</i> at rates used in these experiments, and feeding was not deterred by glufosinate, suggesting that glufosinate application induced resistance. Larval densities on glufosinate-treated and non-treated glufosinate-tolerant rice in field experiments did not differ; however, delayed floods reduced numbers of larvae on rice compared to those on early flooded rice.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11012004-131832 |
| Date | 03 November 2004 |
| Creators | Tindall, Kelly V. |
| Contributors | James A. Ottea, Rodrigo A. Valverde, Eric P. Webster, B. Rogers Leonard, Bill J. Williams, Michael J. Stout |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11012004-131832/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0021 seconds