Call number: LD2668 .T4 1953 C35 / Master of Science

Corn is one of the three most valuable cereals in the world, and at present its adoption as a grain crop in Quebec is being encouraged. [...]

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Call number: LD2668 .T4 1980 W44 / Master of Science

Includes bibliographical references

The seasonal life history of the cereal stem moth (CSM), Ochsenheimeria vacculella Fischer von Roslerstamm, (Lepidoptera : Ochsenheimeriidae) was investigated in a commercial field of annual ryegrass in the Willamette Valley, OR from January 1993 to August 1994. Phenology of life stages, effect of temperature on eclosion, and development of larvae on potential hosts of economic importantce were also studied. First records of parasitization and effects of cultural practices on this potential pest in annual ryegrass were reported. CSM is a recent introduction to North America from a monobasic family of the Palearctic region. Its life cycle is functionally univoltine in commercial ryegrass seed fields. Eggs are characteristically deposited on interior wooden walls, ceilings and straw bales or piles in outbuildings from June through September. Eclosion occurs bimodally with approximately fifty percent of current season eggs hatching in late June and July. The remainder overwinter and hatch in February and March. Larvae ballooned from oviposition sites to potential hosts and were found in annual ryegrass from February to early June. First instar larvae typically mine leaves; later stadia are stem borers. Variance to mean ratios of larvae sampled in annual ryegrass described a clumped population. Pupation occurred from late May to early July. The pupa was enclosed in a flimsy cocoon usually located on the inside of a flag leaf's sheath. Shortly after emergence in early June and July, adults fly to outbuildings preferentially remaining within those where grass straw has been stored. Migration from the field and subsequent flight, copulation and oviposition within buildings occurred only on bright days from approximately noon to 4:30 pm (PDT) through September at which time most adults have died. Two species of larval parasitoids in the Eulophidae and Ichneumonidae were very abundant in the annual ryegrass field under study during June and July 1994. Their combined parasitization rate of CSM larvae exceeded ninety percent. A frequency distribution of head capsule widths indicates CSM larvae probably develop through five instars. However, inter-instar ratios of head capsule widths did not conform to Dyar's hypothesis. Eggs deposited by females collected in the field and allowed to oviposit in the laboratory did not hatch at either room temperature or 6��C. However, cohorts of eggs hatched readily during incubation at either 10�� or 14��C when observed after two and three months exposure. Nine varieties of six commercially important species of grasses and cereals were evaluated for suitability as larval hosts. Annual ryegrass, Lolium multiflorum Lam., consistently supported the greatest population densities in the field and resulted in greatest survival of larvae in laboratory and greenhouse tests. Removal of annual ryegrass foliage in plots during late winter or early spring to simulate the effect of sheep grazing significantly reduced subsequent larval populations relative to plots without vegetation removal. / Graduation date: 1995

There is a need for effective and environmentally sensitive methods of controlling vertebrate pest problems in agriculture and urban environment. Nonlethal natural repellents may meet this need where more traditional methods of control, such as scaring, shooting, and trapping, are either ineffectual or unacceptable. Neem (Azadirachta indica A Juss) extracts: oil, seed and leaf powder and chemicals from cockroach (Blaberus giganteus L.) were tested for their repellent properties. In addition defensive volatiles from B. giganteus were tested in an arena based on choice by smell (cheese or insect volatiles). This arena test used laboratory rats (Rattus norvegicus Berk.); females were more active than males. Both sexes visited the holes with cheese more than holes containing insect's volatiles. However in a feeding test with one choice of food the control did not differ from the treatment. Neem products seem to act as antifeedant on rats: neem seed oil, neem seed powder and neem leaf powder reduced rats feeding respectively at concentration of 15 ml of oil/kg, 15--50 g of seed powder/kg, and 25--50 g of leaf powder/kg of rat chow. Overall neem leaf powder was less effective than seed powder and oil. Neem and insect products may have potential in controlling rats particularly in storage situation, which could lead to an important reduction of post-harvest loss of grains in Sahelian and Asian countries.

Cereal crops such as maize and sorghum are economically important in South Africa (SA) as a staple food diet. In order to meet the needs of South Africa’s growing population, higher yields in crop production need to be attained. However, the two major stress factors that affect yield production and require primary attention are nutrient deficiencies and pest infestations. Research is now being focused on certain endophytes that have become a valuable tool for agriculture as they protect crops against the above-mentioned stresses. The endophyte focused on in this study was Arbuscular Mycorrhizal fungi (AMF). This research was aimed at developing an in vitro culture system for SA cereal crops to enable interaction studies of endophytes. This dissertation is divided into two parts; the first part focused on the development of an in vitro culture system, the assessment of sorghum plant growth and exudate production in the presence of the Glomus intraradices strain. The results indicated that sorghum produces the required root exudates in the second stage of growth. Using high pressure liquid chromatography with mass spectrometry (HPLC/MS), it was noted that sorghum produced phytochemicals as chemoattractants for the respective endophytes. However, it was documented that when the plant underwent certain stresses they produced exudates, which acted as phytotoxic compounds that destroyed symbiotic organisms around sorghum rhizophere. The second part focused on optimization of the surface sterilization of maize seeds. The results indicated that maize contained unidentified endophytes, which negatively affected plant development. Surface sterilization of maize seeds was accomplished. The successful in vitro development can be used for future use to study plant development. Understanding plant development and interaction with symbiotic endophytes would not only be of great benefit but would also make it easier to create a biocontrol agent in vitro, which would bring about high crop yields at cost-effective prices and would be less labour intensive. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Please read the abstract in the section, 00front of this document / Thesis (PhD (Entomology))--University of Pretoria, 2007. / Zoology and Entomology / PhD / unrestricted

Deoxynivalenol (DON), a mycotoxin produced in cereal grains infected by Fusarium Head Blight produced by Fusarium graminearium and Deoxynivalenol-3-β-D-glucopyranoside (DON-3G), were studied during processing using LC-MS-MS and GC. DON reduced significantly (P<0.05) 61.8% during milling into flour. Therefore, DON was concentrated mostly in the bran and germ. DON increased 40.8% during the fermentation stage of baking. DON increased in dough more than flour and mixed dough. Milling reduced by 23.7% but fermentation did not. But bread was significantly lower in DON-3G at 0.15 ppm than flour and dough at 0.31 ppm. The baking increased DON and decreased DON-3G showing a difference in stability of the mycotoxins during processing. Enzyme hydrolysis on DON using α-amylase, cellulase, protease, and xylanase, showed a significant increase with cellulase (20.8%), protease (11.4%), and xylanase (35.6%) compared to wheat composite. DON may be bound to the cell wall or protein component of the kernel.