Bionomics of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, (Coleoptera: Curculionidae) in rice (Oryza sativa L.) /
Studies were conducted to better understand the oviposition behavior of rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, to develop a rearing technique to obtain RWW neonates for toxicological bioassays. RWW females were capable of laying eggs in several sites such as rice roots, leaf sh...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2004.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=766020711&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Studies were conducted to better understand the oviposition behavior of rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, to develop a rearing technique to obtain RWW neonates for toxicological bioassays. RWW females were capable of laying eggs in several sites such as rice roots, leaf sheaths, leaf collars, water surrounding host materials and water only. Roots were the most preferred oviposition site of all, but RWW were able to lay similar numbers of eggs in the presence or absence of rice roots. Water was found to be a suitable oviposition substrate to incorporate in a rearing program. A laboratory rearing technique was developed to obtain RWW neonates. This technique produces a large number of similarly aged high quality neonates without microbial contamination. Moreover, the technique is simple, practical and easy to perform. A root-dip bioassay was developed to evaluate Bt (Bacillus thuringiensis) toxic proteins for RWW larvae. Based on maximum likelihood tests, the root-dip technique was accurate at high concentrations of Cry3A Bt toxin. Avoidance behavior of RWW larvae for a Cry3A Bt formulation was the major limitation for the root-dip technique at low concentrations. Several biological and physiological phenomena were investigated to determine whether RWW in Texas enters reproductive diapause. RWW adults moved to overwintering sites beginning in July. The lack of oocyte development was observed in female RWW in the field as well as females reared in an incubator during the winter. A protein with an approximate molecular weight of 91.4 kDa was abundant in the haemolymph of female RWW during the winter. This indicates RWW in Texas exhibit reproductive diapause during the winter. The feasibility of developing an artificial diet and associated rearing techniques for RWW larvae was investigated. Only 3.4 % of RWW larvae pupated and few adults emerged in a medium of rice roots and agar, but no larvae pupated in other artificial diets tested. Larvae did not pupate on artificial substrates including mud. Based on larval growth and behavior, five out of 17 artificial diets were selected for further improvement. This study revealed the potential for development of a suitable artificial diet for RWW larvae. |
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| Item Description: | Vita. "Major Subject: Entomology". |
| Physical Description: | xix, 293 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 273-287). |