No description available.

Note:

Typescript. Submitted for the degree of Doctor of Philosophy but awarded the degree of Master of Agricultural Science. Bibliography: leaves 76-86.

The limited availability of land to forestry and the ensuing emphasis on intensive silviculture, developed a renewed interest in soil pests in the establishment of plantations. Ten field trials were planted over three seasons to determine the mortality factors influencing the establishment of commercial eucalypt and black wattle plantations in the Natal Midlands, and simultaneously, to investigate the chemical control of the soil pest component. A complex of indigenous soil pests contribute to an average 22,9 % failure of Acacia mearnsii and Eucalyptus grandis seedlings from reaching full establishment. This pest complex, which includes termites, whitegrubs, cutworms, tipulid larvae, wireworms, millipedes and nematodes, was responsible for an average 12,3 % of the failure of the plantings to establish. In the absence of termites, in shallow humic soils, whitegrubs followed by cutworms were the most frequent and economically important pests. Eucalypts are more susceptible than wattle seedlings to whitegrub damage when planted in marginal sites. Seedlings in the summer rainfall region were most susceptible to whitegrub damage from December to April; and to cutworm damage during the first two months after planting. An average of 398 hectares was annually damaged by whitegrubs and cutworms. The total annual loss in planting costs and the additional costs of blanking over the three year study period were 1,22 and 2,65 million rands respectively. Existing non-chemical control applicable to woodlot forestry is reported. Chemical control as one of the options in the management of whitegrubs and cutworms was evaluated. The controlled release formulations of carbosulfan 10% and chlorpyrifos 10% at 1,0 g active ingredient/tree (a.i./tree), gamma BRC 0,6% dust at 0,06 g a.i./tree and the synthetic pyrethroid deltamethrin 5 % SC at 0,025 g a.i./tree were persistent and effective in controlling whitegrubs, even when applied early in the planting season. Deltamethrin 5 % SC at 0,025 g a.i./tree was also successful in controlling cutworms. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

The formulation of Dursban®, manufactured by Dow Chemical Corp., and its diluting agent were found to influence the penetration abilities of the final spray when it is applied to pine sapwood. The diluent of choice for providing the best penetration of the active ingredient, chlorpyrifos, is an Oil-based carrier for the formulated product Dursban® WT. Dursban® TC, another product containing chlorpyrifos, will penetrate the wood surface better when diluted with water, not with an oil-based carrier such as kerosene. Residual amounts of Dursban® TC applied to pine sapwood will remain relatively constant six months after the initial treatment at depths of 400 - 600 microns below the surface. The wood moisture content (WMC) of treated pine sapwood did not significantly influence the penetration abilities of Dursban® TC at 7.5% - 8.0% and 14.5% - 16.0% WMC. A 1.0% water-diluted formulation of Dursban® TC applied to pine sapwood is predicted to be capable of penetrating the treated wood to a depth of 1320 microns. / Master of Science

Made available in DSpace on 2016-12-08T16:44:53Z (GMT). No. of bitstreams: 1 PGPV07MA012.pdf: 939412 bytes, checksum: 9219a6a0e6110448ce6a16cbcdc3b13d (MD5) Previous issue date: 2007-03-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The irrigate rice culture of the Santa Catarina Stade has a great economic and social importance and it is cultivated mainly by little farmers. The total production of grains obtained from rice fields in Santa Catarina State is higher than that ones from others rice regions of the country. Despite of the high indices of production the rice farmers find out difficulties with pest management. The rice steam bug (Tibraca limbativentris) Stal, 1860 (Hemiptera: Pentatomidae) has a great economic importance because the significant losses that causes to the irrigated rice fields. Currently, its control is done using a lot of chemical insecticides. The intense use of chemical products has adverse affects on the health of the farmers and is an eminent threat to the contamination of the water resources. The objective of this work was to carry on a survey and the identification of species of eggs parasitoids of T. limbativentris with natural occurrence in the rice fields of Santa Catarina State, as well as studying in laboratory some biological aspects of the parasitoids. The survey was carried on in the field rice of the regions of the High, Middle and Low Itajaí Valley. Two parasitoids species Telenomus podisi and Trissolcus urichi were recovered. The species T. podisi was the most abundant in all regions. By carrying out bioassays it was evaluated the potential of parasitism of T. podisi on eggs of T.limbativentris. It was observed that T. podisi showed an index of parasitism above of 70%. The longevity of the females was of 5,97 days. The period of egg-adult was of 10,1 days. The fecundity of individualized females of T. podisi was 11,49 insects. The average of sex ration of individualized females was higher than 0,6. The time exposition bioassay shoed that when the T. podisi female were exposed to fresh eggs of T. limbativentris above 8 hours the sex ratio presented was constant to all the time exposition, 0,8. Parasitism bioassays with eggs of T. limbativentris stored by 30 days at -18 0C and fresh eggs showed that the average index of parasitism on fresh eggs was 93.3 % and on stored eggs was 35.2%. The average index of parasitism on stored eggs in the field conditions was 13.7%. From the results obtained by doing this work it can be concluded that the use of eggs parasitoids such as T. podisi in the biological control of the rice steam bug could be an important tool to be incorporated the programs of integrated management of pest in the irrigated rice fields in order to minimize and/or to eliminate the intense use of chemical insecticides / A cultura do arroz irrigado em Santa Catarina possui importância econômica e social, é típica de pequena propriedade e a mão-de-obra utilizada é familiar. O rendimento de grãos obtido nas lavouras orizícolas em Santa Catarina supera aquela obtida em outros estados produtores de arroz. Apesar dos altos índices de produção os rizicultores encontram dificuldades no manejo de pragas. O percevejo-do-colmo (Tibraca limbativentris) Stal, 1860 (Hemiptera: Pentatomidae) possui importância pelas perdas que causa na cultura do arroz irrigado. Atualmente o seu controle restringe-se apenas a aplicações de inseticidas químicos. O intenso uso de agrotóxicos afeta saúde dos agricultores e se constitui numa ameaça a contaminação dos recursos hídricos. Neste sentido objetivou-se neste trabalho realizar o levantamento e a identificação de espécies de microhimenópteros parasitóides de ovos de T. limbativentris com ocorrência natural nas lavouras arrozeiras catarinenses, bem como estudar em laboratório alguns aspectos biológicos do parasitóide. O levantamento de ovos parasitados foi realizado em lavouras de arroz das regiões do Alto, Médio e Baixo Vale do Itajaí, Norte e Sul do estado. Foram identificadas as espécies Telenomus podisi e Trissolcus urichi. A espécie T. podisi foi a mais abundante em todas as regiões Nos bioensaios realizados em laboratório avaliou-se o potencial de parasitismo apresentado pela espécie T. podisi sobre ovos de T. limbativentris, observando que a espécie apresenta um índice de parasitismo acima de 70%. A longevidade das fêmeas foi de 5,97 dias. O período de ovo-adulto foi de 10,1 dias. As fêmeas individualizadas apresentaram fecundidade média de 11,49 insetos. A razão sexual obtida foi superior a 0,6. Em teste realizado para verificar a influência do tempo de contato de fêmeas do parasitóide com ovos do hospedeiro na razão sexual da progênie do parasitóide, os resultados demonstram que após 8 horas de exposição a razão sexual manteve-se estável em 0,8. O índice de parasitismo de ovos armazenados em relação a ovos frescos também foi avaliado, oferecendo-se ovos de T. limbativentris armazenados a -18 oC durante 30 dias e ovos frescos ao parasitóide em laboratório por um período de cinco a 25 horas. O índice médio obtido foi de 93,3% de parasitismo em ovos frescos e 35,2% em ovos armazenados. O índice médio de parasitismo de ovos armazenados oferecidos ao parasitóide a campo foi de 13,7%. Com a realização deste trabalho observou-se que a utilização de parasitóides de ovos para o controle biológico do percevejo-do-colmo poderá ser uma importante prática a ser incorporada aos programas de manejo integrado de pragas nos cultivos de arroz irrigado, a fim de minimizar e/ou eliminar o intenso uso de inseticidas químicos para o controle do percevejo-do-colmo