Thesis (Ph.D.). / Written for the Dept. of Natural Resource Sciences, Macdonald College of McGill University. Title from title page of PDF (viewed 2008/08/04). Includes bibliographical references.

Three distinct plant viruses, transmitted by the tobacco whitefly Bemisia tabaci Genn., were associated with diseased food or fiber crops grown in the southwestern deserts of Arizona. The cotton leaf crumple virus (CLCV), thought to affect only cotton Gossypium (L.) spp., is now known to infect other malvaceous plants and members of the Convolvulaceae and Leguminosae. Results of an experimental host range study suggest that potential virus-vector reservoirs may exist in cotton growing regions which include both weeds and cultivated plants. Geminivirus-like (GVL) particles of ∼18 x 30 nm were isolated for the first time from CLCV-infected bean, Phaseolus vulgaris (L.), 'Red Kidney', a plant which was a better purification host than cotton. Studies of CLCV-vector relationships indicated that the acquisition- and inoculation-access times, latent period and length of retention by whitefly vectors were similar to those of the original isolate reported in California in 1954. When growth chamber temperatures of 26, 32, and 37C were used in virus-vector studies, optimal acquisition and transmission occurred at 32C while temperatures of 37C were lethal to whitefly adults. Two additional virus-like agents were isolated from single and mixed infections of lettuce or melons, respectively. The virus-like agent from lettuce infected primarily members of the Chenopodiaceae, Compositae and Cucurbitaceae, and was whitefly but not mechanically transmissible. Long flexuous closterovirus-like rods of ∼10 x 1400-2000 nm were visualized in extracts prepared from plants inoculated with the lettuce isolate. The isolate was similar to the lettuce infectious yellow virus (LIYV) based upon host range, transmission characteristics and unique particle morphology. Both long flexuous rods like those associated with the lettuce isolate and GVL particles of 18 x 30 nm were associated with diseased melons. The host range of the GVL agent was confined to the Cucurbitaceae and Leguminosae and the agent was separated from the mixed infection by mechanical transmission to a non-LIYV host. The GVL-agent was distinct from previously described cucurbit viruses including the squash leaf curl virus, based upon host range and transmission characteristics and was tentatively designated as the watermelon curly mottle virus (WCMV).

No description available.

Field and laboratory investigations were conducted in Burkina Faso to diagnose the causes of severe outbreaks of Bemisia tabaci populations and gênerai failures of chemical control against this pest in cotton. / Field and laboratory investigations were conducted in Burkina Faso to diagnose the causes of severe outbreaks of Bemisia tabaci populations and general failures of chemical control against this pest in cotton. The research efforts were oriented in the following three areas: I) the susceptibility of B. tabaci populations and its parasitoids to cotton insecticides; I) the susceptibility of B. tabaci populations and its parasitoids to cotton insecticides, a) conventional insecticides, b) novel insecticides; II) the relative abundance of B. tabaci and its parasitoids in the field; III) the biological activities of some botanical extracts as alternative insecticides against the pest.

A dissertation submitted in partial compliance with the requirements for the Masters Degree in technology: Homoeopathy, Technikon Natal, 1999. / The most common and difficult insect to control in the greenhouse is the whitefly. Sweetpotato whitefly (Bemisia tabaci Genn.) was the species of whitefly selected to be investigated in this trial. Sweetpotato whitefly is a major pest on a variety of plants, ranging from ornamental flowers to agricultural crops such as tomato and cotton, resulting in important financial losses. Effective control options of sweetpotato whitefly are limited. / M

No description available.

Diploma Thesis concerns with usage of entomopathogenic fungi in system of biological control against greenhouse whitefly Trialeurodoes vaporariorum and sweetpotato whitefly Bemisia tabaci. The Aim of diploma thesis was through in vivo and in vitro experiments determinated the basic evolutional and vegetative characteristics of selected entomopathogenic fungi and compare their effectivity in completed system {\clqq}plant - pest - pathogenic``. All experiments and results are demonstrated in the tables and the graphs. The photo-documentation of the method used during founding and interpretation of experiments is the part of the thesis.