Scholarship & Research
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Item Sex ratio studies on the wheat stem sawfly, Cephus Cinctus Nort(Montana State University - Bozeman, College of Agriculture, 1950) McGinnis, Arthur JamesItem Oviposition of the wheat stem sawfly (Cephus cinctus, Nort.) with special reference to some morphological characteristics of vulgare wheats(Montana State University - Bozeman, College of Agriculture, 1955) Kreasky, Joseph B.Item Initiation of post-diapause development and reinstatement of diapause in Cephus Cinctus Nort.(Montana State University - Bozeman, College of Agriculture, 1953) Church, Norman StanleyItem Blending resistant and susceptible winter wheat for wheat stem sawfly (Cephus cinctus Norton) management(Montana State University - Bozeman, College of Agriculture, 2003) Waters, Debra KayItem Wheat stem sawfly parasitism in varying field sizes and tillage systems in dryland wheat in Montana(Montana State University - Bozeman, College of Agriculture, 2001) Runyon, Justin BlakeItem In field distributions of the wheat stem sawfly, (Hymenoptera: Cephidae), and evaluation of selected tactics for an integrated management program(Montana State University - Bozeman, College of Agriculture, 1999) Goosey, Hayes BlakeItem Morphological resistance of some of the Gramineae to the wheat stem sawfly (Cephus Cinctus Norton)(Montana State University - Bozeman, College of Agriculture, 1954) Roemhild, George R.Item Mass rearing of Bracon cephi (Gahan) and B. lissogaster Muesebeck parasitoids of wheat stem sawfly, Cephus cinctus Norton, and temperature-induced mortality in host immatures(Montana State University - Bozeman, College of Agriculture, 2006) Robert, Godshen Robert Pallipparambil; Chairperson, Graduate Committee: David K. Weaver.Bracon cephi (Gahan) and B. lissogaster Muesebeck are host specific larval parasitoids of the wheat stem sawfly, Cephus cinctus Norton. A reliable source of these parasitoids is needed for inoculative releases into sawfly infested wheat fields in Montana. Large walk-in field screen cages were used to confine sawflies and parasitoids on wheat. Factors affecting the successful establishment of sawflies in wheat and subsequent attack by parasitoids were tested. Treatments consisted of cage modifications such as windows for enhancing the amount of light, food sources for parasitoids, increased light plus food sources, and a control. Methods for delivering adult sawflies into the cages were also investigated. The mass rearing cages with the windows had significantly greater sawfly infestation and parasitism when compared to the cages without windows. The sawfly infestation was low the first year, while the percent parasitism was quite high, indicating that the major impediment to mass rearing was obtaining greater sawfly infestation. We obtained higher amounts of infestation and parasitism for the second year when the method of introduction of C. cinctus adults into the rearing cage was changed, and this difference was more obvious than any treatment effects.Item Potential semiochemicals of wheat (Triticum aestivum L.) induced by oviposition and feeding of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae)(Montana State University - Bozeman, College of Agriculture, 2004) Peck, Gavin Earl; Chairperson, Graduate Committee: David K. Weaver.Cephus cinctus Norton (Hymenoptera: Cephidae), the wheat stem sawfly, is currently the most devastating insect pest of wheat production in Montana. Currently, no effective controls are in place to check its damage and spread throughout wheat fields in the northern Great Plains. Natural biological control of sawflies occurs primarily in the form of larval parasitoids which attack the sawfly larva in the stem; however, these parasitoids are not reliably effective in controlling sawfly populations. Insect damage induces chemical changes in plants, and often these changes are part of a defensive response to the insect injury. Some of these chemical changes are apparent in the volatile chemicals produced by the plants and may include semiochemicals used by sawflies and parasitoids. Identifying the changes in volatile production could enhance the understanding of sawfly-wheat plant-parasitoid interactions and lead to more effective control measures for the wheat stem sawfly. I investigated the differences in the volatile chemicals produced by sawfly-infested and uninfested wheat plants and endeavored to determine if those differences were qualitative or quantitative. Additionally, I wanted to determine if changes in volatile production induced by the wheat stem sawfly could be mimicked by wounding coupled with the application of sawfly cuticular wax to wheat stems or by the injection of frass-treated water into the internodes of wheat stems. Volatiles of infested and uninfested wheat plants were collected and compared, with the results indicating that sawfly damage induces quantitative changes in some volatile chemicals produced by wheat. These results are discussed regarding their context within sawfly-wheat plant-parasitoid interactions and implications for better sawfly control. Volatiles from sawfly-infested, uninfested, frass-water-injected, and pin-pricked/waxtreated plants were also collected, and differences in 11 compounds selected from the results of the 1st experiment were compared. The results of this experiment found that pin-pricked/wax-treated plants came closer to mimicking the volatile production changes induced by sawfly infestation, but neither frass-water injection nor pin-pricked/cuticular wax application reliably induced the same changes in wheat volatiles that sawfly infestation did. There was, however, a definite response of the wheat to the application of the sawfly cuticular wax, and its significance is discussed.Item Impact of harvest operations on parasitism of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae)(Montana State University - Bozeman, College of Agriculture, 2005) Meers, Scott Byron; Chairperson, Graduate Committee: Wendell L. Morrill.Wheat stem sawfly, Cephus cinctus, has been a long term pest management challenge for wheat producers in Alberta, Saskatchewan, North Dakota and Montana. Many studies have laid the groundwork for biological control of this pest. Two species of parasitoids, Bracon cephi and B. lissogaster, have been shown to effectively attack C. cinctus in wheat Triticum aestivum L. Their effectiveness as part of an integrated pest management plan, however, has been highly variable. A survey was conducted to assess the distribution of the two Bracon parasitoids. A two pronged approach was used to better understand parasitoid spatial dynamics and parasitoid promotion. First, intensive field sampling was performed to determine the overwintering location of parasitoid cocoons in wheat fields. Second, wheat stems were cut at varying lengths to stimulate harvest management techniques that producers could employ. B. cephi occurred at most locations where sawflies were an agricultural concern, although the level is sometimes very low. B. lissogaster was only found in wheat in Montana. The vast majority of overwintering cocoons (>80%) were consistently found in the bottom third of standing wheat stems when measured prior to harvest.