Thesis (PhD)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Patrick G. Hatfield. Includes bibliographical references (leaves 57-68).

Thesis (Ph. D.)--Michigan State University. Dept. of Entomology, 2008. / Title from PDF t.p. (viewed on Aug. 19, 2009) Includes bibliographical references (p. 233-248). Also issued in print.

Thesis (Ph. D.) -- Lincoln University, 2004. / Also available via the World Wide Web.

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Tobacco rattle virus (TRY) and trichodorid vector nematodes were found to be widespread in bulb growing areas in The Netherlands. Indications, obtained from pot bait tests, that associations between serotypes of tobacco rattle virus and Paratrichodorus and Trichodorus vector species occurred were confirmed in bait tests using individual trichodorid nematodes. Whereas different Paratrichodorus vector species each transmitted a serologically distinct TRV-isolate, different Trichodorus vector species transmitted serologically indistinguishable TRV-isolates. It remains to be studied whether a particular Trichodorus species is able to transmit all isolates serologically indistinguishable from the one with which it was naturally associated. A TRV-isolate transmitted by T. cylindricus from Scryne, Scotland and isolates transmitted by P. teres from Julianadorp, The Netherlands were considered anomalous TRV-isolates as they serologically resembled pea early-browning virus but had RNA-1 sequences typical of TRV. Virus-free P. pachydermus from Scotland and from The Netherlands acquired and subsequently transmitted TRV-isolates originally obtained from bait-plants infected by P. pachydermus from Scotland or The Netherlands. They failed to transmit a serologically similar isolate obtained from an infected potato tuber. Virus-free P. pachydermus did not acquire and transmit a pseudorecombinant TRV-isolate with the RNA-2 from a non-transmissible isolate, but efficiently transmitted a pseudorecombinant isolate in which the RNA-2 was derived from a efficiently transmitted isolate. This indicated that transmissibility is most likely determined by the virus coat-protein. Transgenic tobacco plants, expressing TRV coat-protein were resistant to mechanical inoculation but susceptible to nematode transmission of the virus. A possible low level of coat-protein expression in the roots could not fully explain this result as the nematodes also transmitted TRV directly to detached leaves of such transgenic plants.

Orientador: Ana Maria Costa Leonardo / Banca: Sulene Noriko Shima / Banca: José Eduardo Marcondes de Almeida / Resumo: A espécie exótica de cupim Coptotermes gestroi (Família Rhinotermitidae) é considerada uma das pragas urbanas economicamente mais importantes no Brasil. O seu hábito críptico limita os estudos sobre sua biologia e comportamento, o que dificulta um controle realmente efetivo. Uma forma de controle biorracional é a tecnologia de iscas, já que leva em consideração o comportamento social desses insetos, além de preservar o meio ambiente. Seu princípio é a transmissão de agentes químicos ou biológicos diretamente para os cupins, visando atingir toda a colônia. A isca é composta por ingredientes ativos incorporados a substratos que contenham celulose. Para que o controle seja mais eficiente, esses substratos devem ser atrativos aos cupins, estimulando o recrutamento e a atividade de alimentação dos indivíduos. Em vista do exposto, a presente pesquisa propôs, por meio de testes laboratoriais e de campo, selecionar substratos celulósicos mais atrativos e adequados à incorporação de ingredientes ativos. Inicialmente foram testados 12 tipos de substratos, e a partir desses, selecionados 4 que foram utilizados nos bioensaios posteriores. O período de duração dos testes laboratoriais foi de 28 dias. Já para os testes de campo foram executados 8 ciclos experimentais, sendo que cada ciclo durou 7 dias. Todos os resultados foram analisados estatisticamente, com nível de significância (á) igual a 0,05. Os resultados obtidos evidenciaram que os substratos mais atrativos para C. gestroi foram papelão corrugado e colmo de milho. Tais fontes celulósicas...(Resumo completo clicar acesso eletrônico abaixo) / Abstract: The exotic species of termite Coptotermes gestroi (Family Rhinotermitidae) is considered one of the most important urban pests in Brazil. Its cryptic habit limits the studies about its biology and behavior, what difficult an effective control. A way to perform biorrational control of termites is the bait technology, since it considers the social behavior of these insects beyond preserving the environment. Its principle is the transmission of chemical or biological agents straightly for the termites, aiming to reach the whole colony. The bait is composed by active ingredients incorporated to substrates that contain cellulose. In order to improve the efficiency of the bait control, these substrates must be attractive to the termites, stimulating the recruitment and the feeding activity of the individuals. Based on the presented background, this research proposed, by means of laboratory and field tests, to select cellulosic substrates more attractive and suitable to adding the active ingredients. Initially, twelve types of substrates were tested, and four of them were selected, which had been used in the posterior bioassays. The laboratory tests were processed along 28 days, while the field tests demanded eight experimental cycles, each of them during 7 days. All the results were statistically analyzed, at a significance level (á) of 0.05. The results showed that the most attractive substrates for C. gestroi were corrugated cardboard and corn stem. Such cellulosic sources were clearly more consumed than the other materials; in addition they had recruited a large number of individuals to the baits. Some Abstract 4 factors must be considered in the matrix choice, such as their manipulation and viability to termiticid impregnation, aiming to the contribution for the development of more efficient baits in the termite control. / Mestre

Ph.D. (Botany) / Please refer to full text to view abstract

M.Sc. / The extent of economic damage caused to the cotton variety Acala 1517/70 by the feeding activities of Tetranychus cinnabarinus (Boisduval) has been studies at the Loskop Research Station, situated in the Transvaal Middleveld. Special attention is given to the relative importance of the occurrence of spider mite infestations during the various stadia in the development of the cotton plant. the common method by which the extent of mite infestations is calculated, namely the conversion of adult female counts to female-days / leaf is used, and this unit of measure is compared to the percentage of leaf surface area over which visible damage extends (trial 1) as well as to the actual damaged leaf surface area. An index system is used to determine the percentage of leaf surface area over which visible damage extends (trial 1). The effectiveness of this procedure in determining the actual damaged leaf surface area is found to be sufficient, and is recommended as it appears to be a rapid and accurate method for evaluation during field trials. In accordance with quoted literature it is determined that the regression of both the leaf surface area over which damage extends (as determined by the index system as described) and the actual damaged leaf surface area against the female-days I leaf at a specific stage, are highly significant. It is confirmed that the use of either the percentage of leaf surface area over which damage extends or the actual damaged leaf surface area is valid. A method that is based on the use of female-days) leaf, but which in addition takes into account the stage (in days after planting) at which a particular spider mite count has been present is developed for the purposes of this study. It has been confirmed that this particular unit (damagedays IleaO has practical application value. It is pointed out that even in the early stages of population buildup there exists a highly significant relationship between both the femaledays / leaf and the damage-days Ileaf,and the yield masses. Significant reductions of up to 16 percent in yield were found in spite of the fact that notable spider mite infestations had not occurred prior to the flowering peak. By taking the value of the cotton yield into account and comparing it with the cost of control, an economic evaluation of the specific treatments is made. The following important conclusions were reached: • The confirmation of the profitability of applying an acaricide (triazophos) as soon as the first signs of a red spider mite infestation is discovered. • the irrelevance of programme spraying regardless of the infestation present, • the decrease in relative importance of red spider mide infestations in the later stages of the development of the cotton plant, and • the probability of spider mites affecting both the yield mass and quality if heavy infestations prevail after 19 weeks (133 days) after planting.

M.Sc. (Biochemistry) / Please refer to full text to view abstract