Plant Sciences electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Division of Plant Sciences. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Development and behavior of a braconid ectoparasite, Iphiaulax kimballi Kirkland (Hymenoptera: braconidae), of the southwestern corn borer, Diatraea grandiosella dyar (Lepidoptera: pyralidae)(University of Missouri--Columbia, 1983) Lee, How-Jing; Chippendale, G. M."The southwestern corn borer, Djatraea grandiosella Dyar, entered the United States from Mexico. Since the first record of its presence in New Mexico in 1913, it has become a destructive pest of corn and sorghum in the southern corn belt (Davis, et al., 1933; Gerhardt, et al., 1972; Morrison, et al., 1977; Chippendale, 1979). After the southwestern corn borer dispersed into the United States, it gradually spread in an easterly direction (Davis, et al., 1933; Henderson, et al., 1966; Anonymous, 1974; Chippendale and Reddy, 1974). It is presently established in 13 states, ranging from Arizona to Alabama (Chippendale, 1979). The rate of dispersal of D. grandiosella has been estimated at 13 miles per year from 1913 to 1931, 20 miles per year from 1932 to 1953, 35 miles per year from 1954 to 1964, and 12 miles per year after 1965 (Fairchild, et al., 1965; Chippendale, 1979). At present the distribution limits of the insect appear to be reasonably stable. Since a high mortality of diapausing larvae of D. grandiosella occurs during the winter in south-central Kansas and southern Missouri, the northern limits have been reached at about 38 [degree] N latitude. The southern Atlantic states which have mild weather during the winter and suitable host plants may become colonized by D. grandiosella (Chippendale, 1979). The southwestern corn borer damages the corn plant at all stages of its growth and development. Yield losses by D. grandiosella are caused mainly from dead heart, larvae tunneling in the stalk and ear, and lodging due to girdling. This insect causes substantial economic losses, and its economic impact increased as its range of infestation expanded into important corn-growing regions. In an effort to find natural enemies for the southwestern corn borer in its original habitat in Mexico, Kirkland (1983) carried out an exploration in Morelos, Michoacan, Nayarit, Veracruz, Queretaro, Jalisco. Guanajuato, Mexico, and Puebla. He found in Morelos and Veracruz a natural enemy, a braconid ectoparasite, Iphiaulax kimballi Kirkland (Kirkland, 1982), which parasitize mature larvae of D. grandiosella. Female adults of I. kimballi inject venom to paralyze larvae of D. grandiosella before they oviposit on their integument. Several larvae of I. kimballi complete their development on a single host. This parasite may have a significant impact in reducing population levels of D. grandiosella in some areas of Mexico. It is, therefore, a candidate for the biological control of the southwestern corn borer in the United States. Since I. kimballi is a newly described species (Kirkland, 1982), little information is available about its growth, development, life cycle, and behavior. The objective of this study was to obtain fundamental information about the development and behavior of I. kimballi and to evaluate the species, in the laboratory, as a potential parasite of the southwestern corn borer in the United States. Experiments were carried out to: (1) study the effects of temperature on the development of I. kimballi; (2) examine the function of venom; (3) investigate the relationship between the parasite and the southwestern corn borer; (4) examine whether methoprene -treated southwestern corn borers can serve as hosts for the parasite; and (5) examine host selection and host searching behavior of the parasite."--Introduction.Item Palynology of the Hannibal Formation (Lower Mississippian) of northeast Missouri and western Illinois(University of Missouri--Columbia, 1968) Brown, Dwight Delon"The purpose of this study is to describe and illus trate the miospore, acritarch, and Tasmanites assemblages which are present in the Lower Mississippian Hannibal Formation of northeast Missouri and western Illinois, and to determine the botanical, stratigraphical, and paleo-ecological significance of the assemblages. This research project was initiated in the summer of 1964 under the direction of Dr. J. M. Wood who foresaw the need to fill the void in palynological information regarding the occurrence of Mississippian miospores in Missouri sediments. The present study is the first report on the Lower Mississippian miospores of Missouri and Illinois. The one other report concerned with Lower Mississippian miospores in the United States is that of Winslow (1962). An abundant acritarch assemblage is reported here for the first time from the Lower Mississippian strata of North America."--Page 2.Item A study of the myxobacterial-eubacterial association(University of Missouri--Columbia, 1964) Brockman, Ellis R.; Peterson, John E."The myxobacteria are an unusual group of micro-organisms in many respects. One of the interesting aspects of these organisms is that many of them are closely associated with eubacteria; hence, they sometimes require a considerable amount of patience and skill to isolate into pure culture. (The word eubacteria will be used throughout this dissertation to describe the bacteria associated with myxobacteria, regardless of whether they belong to Order I., Pseudomonadales, or to Order IV., Eubacteriales, of the Division Protophyta.) Unlike most of the eubacteria with which they are often closely associated, the myxobacteria produce large quantities of polysaccharide slime around themselves. The abundance and nature of the slime, in which eubacteria are obviously often entrapped, no doubt hinders routine bacteriological purification techniques. The concept that myxobacteria are difficult to purify is not new, for scattered throughout the literature on the myxobacteria are numerous references that attest to this problem. Some of the most obvious of these references are: "difficulty in inducing it to grow pure" (Thaxter, 1097), "impurities" (Thaxter, 1904), "Rohkultur" (Baur, 1904), and "impure culture" (Kofler, 1913). One early reference (Pinoy, 1921) suggested that the relationship was more than a simple physical entrapment of the eubacterial cells in the slime surrounding the myxobacteria. Pinoy coined the name Synbacteria to encompass the myxobacteria and the associated eubacteria and, thereby, implied a symbiotic association between the myxobacteria and their associated eubacteria. Although this view must have seemed reasonable to Pinoy at the time, it was, nevertheless, quite illogical to classify two different organisms as one. Needless to say, the name Synbacteria has only historical significance today. The word association is defined in Webster’s dictionary as "anything closely or usually connected with another". This definition is accepted in this dissertation, and is implied whenever the word association is used to describe the myxobacterial-eubacterial relationship. References, both direct and indirect, have been made in the literature to the relatively constant association of myxobacteria and eubacteria, although little effort has been expended to elucidate the nature of this association. Therefore, the primary goal of the study reported here was to in vestigate the qualitative and quantitative aspects of the myxobacterial-eubacterial association. Essentially, this consisted of a compilation of the overall species-to-species relationship. As a secondary goal, the study investigated in more detail one particular association, that involving the fruiting myxobacterium, Myxococcus fulvus, and a Gram-negative eubacterium on which it was found growing, Alcaligenes viscolactis."--Introduction.Item A study of fusarium wilt resistance in tomato plants(University of Missouri--Columbia, 1953) Baumgardt, John Philip"Several strains of tomatoes, Lycopersicon esculentum, Lycopersicon pimpinellifolium, and hybrids of the two, were subjected to races 1 and 2 of Fusarium oxysporum f. lycopersici. The method of treatment was to excise a lateral root (in most cases), expose the wounded portion to some preparation of the fungus, either a mycelium pad, a cell free suspension of Richard's solution in which the fungus had been grown for three weeks, or a homogenate prepared by grinding in a Waring Blender a mycelium mat along with the Richard's solution in which it had been grown for three weeks. After various periods of exposure to the fungus preparation the plant roots, and in some cases the stems Just above the first internode, were dissected and portions of the primary root (and stem) were furthered sectioned, free hand, and microchemical tests were run on the fresh tissues. In all cases several serial sections were taken and any given test was considered unsatisfactory unless all the sections gave identical results. The xylem reactions were of prime interest in this study. Since one aim of the research was to elaborate further the findings of Finley concerning plugging material found within xylem elements special care was taken to seek out and attempt to identify the compounds comprising this obstruction. Two sorts of tests were run: the first series were intended to identify large organic groups of material present, and the second series was designed to give some idea of inorganic ions and radicals that may be found in the xylem. During the course of the investigation it became evident that two effects wore being expressed using the Finley technique: i.e., a wound response was being expressed in the same general area of the primary root that any sort of resistance reaction capable of being produced by the plant was also realised. In an effort to circumvent this difficulty Haymaker’s technique of utilising an almost undisturbed root system and still obtaining the resistance reaction was adopted. The general indications from the microchemical tests of the roots from a histological aspect were remarkably consistent. The basic distribution of pentoses and pentosans and of the polyphenols identified as such by the Hoepfner-Vorsats test seemed to correlate exactly with the degree of resistance expressed by the plants. In metabolically active cells surrounding the mature xylem these substances, in resistant plants, seemed to occur in amounts far exceeding those found in susceptible plants. Furthermore, plants shown to be capable of developing plugging within parasitised xylem elements were invariably shown to contain the above described distribution of pentoses, pentosans, and poly-phenols. The plugging material produced by almost all tomato plants subsequent to excision of a lateral root was identified tentatively as Molisch's and Tunmann’s wound gum. This material was produced at such a time as to be beyond consideration as a basis of Fusarium resistance, but acted solely as a wound protecting cicatrix. However the so-called resistant plants were observed to produce further plugging of quite a different nature (in this case, apparently a pectic gel) far in advance of the fungus invasion. Furthermore, simultaneously a sudden flush of polyphenols appeared in the active xylem sheathing cells. It was tentatively concluded that these latter effects, the intracellular pectic gelling and the surrounding mobilisation were active expressions of a resistance reaction capable of discouraging further advance of the fungus, and inhibiting any expression of pathogenicity of those hyphae already present in the host. Since it was also noted that living Fusarium did often occur within the plant body of a healthy host, it is suggested that these plants be referred to as Fusarium tolerant, rather than Fusarium resistant."--Summary.Item The fossil flora of the drywood formation of southwestern Missouri(University of Missouri--Columbia, 1965) Basson, Philip Walter"The purpose of this study is to clarify and enlarge upon a previous research which defined the fossil flora of the Lower Coal Measures of Missouri. The former study was based almost entirely on materials that had been collected by individuals in Henry County, Missouri, who had forwarded the floral elements to Washington, D. C. for Identification. Since such collections usually are made up of better preserved materials rather than of all the taxa that may be present, it was felt that the previous collections may have contained a bias and hence the report did not give a complete picture of the flora. Recent information on the Rowe coal reveals an extensive area in which the stratum is exposed. It is questionable whether the previous study, based on a very limited area, gave a true representation of the fossil flora found stratigraphically between the Rowe coal and the Dry-wood coal. It is also questionable whether the strata were accurately defined if the specimens were mail order. Therefore, the major goals of this study were to collect plant macrofossils over a larger area to obtain a larger sample and to carefully define the strata from which these fossils were taken. Secondarily, the flora was also to be more carefully identified in light of the numerous studies made on the Pennsylvanian floras since the original work by White (1899). The flora will be compared with floras from other areas in order to determine similarities and to more clearly define the stratigraphic problems involved."--Introduction.