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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Controle biológico de nematodioses gastrintestinais de bovinos com o fungo predador de nematóides Duddingtonia flagrans na região de Viçosa - Minas Gerais / Biological control of cattle gastrointestinal nematodiosis with nematophagous fungi Duddingtonia flagrans in the region Viçosa - Minas Gerais State, Brazil

Dias, Anderson Silva 23 March 2006 (has links)
Made available in DSpace on 2015-03-26T13:46:34Z (GMT). No. of bitstreams: 1 texto completo.pdf: 205677 bytes, checksum: 93ca0cf3833e543ffed5592e081337ba (MD5) Previous issue date: 2006-03-23 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The viability of the formulation with nematophagous fungi D. flagrans was evaluated in the biological control of cattle gastrointestinal nematodes. Two groups, with eight Holsteinzebu calves each, it was placed in two lots grazed with Brachiaria decumbens on four hectare each one. The experiment started in March of 2005 and turn off in September of 2005. In the control group (A), each animal received 20 grams without fungus of the pellets; in the treated group (B), the animals received 20 grams of with D. flagrans fungus pellets. The counting of the infective larvae recovered in the paddock of the group B, it harvested until 20 centimeters of the distance in the dung pats, it was lower than in the plot A (P<0.01) harvested until 20 centimeters in the distance in the dung pat), there was significative reduction in the larvae recovered in the pasture in 53, 71, 65 e 85 %, respectably, in the April, July, August and September months. The genera Cooperia was the most prevalence (59.9 %). The monthly averages of the weight were bigger in the group B (P<0.05), there was difference between the group B and A in relation in profit weight, in June, July, August and September in de 21, 13, 8,5 e 20 %, respectably. The accountings of the egg per grams of the feces were obtained by the of the Gordon & Whitlock; modified by Lima, and of the Wisconsin of the Cox & Todd, for dairy cattle, modified by Ito techniques and they present differences in the value of the eggs per grams counts for control and treated group (P<0.05). It was observed significative reduction in the count eggs obtained by Gordon & Whitlock technique in May, June, July and August months in treated group in the 35, 46, 36 e 30 % , respectably e do not significative reduction in September (26 %). By Wisconsin modified technique, it there were difference in the June, July and August months in 58, 47 e 51 %, in the treated group, in relation in the control group and do not significative reduction in May (26 %) and September (25 %). It can to conclude that the application of the sodium alginate pellets with nematophagous fungus D. flagrans is effective in the control of the infective larvae of the bovine. / A viabilidade de uma formulação de fungo nematófago Duddingtonia flagrans foi avaliada no controle biológico de nematóides parasitos gastrintestinais de bovinos. Dois grupos de oito bezerros cada, mestiços Holandês-zebu foram colocados em duas pastagens de Brachiaria decumbens de 4 hectares cada. O experimento foi realizado no período de março a setembro de 2005. No grupo controle (A), os animais receberam 20 gramas de péletes sem fungo; no grupo tratado (B), os animais receberam 20 gramas de péletes com o fungo D. flagrans via oral. As contagens de larvas infectantes encontradas na pastagem B, coletadas até 20 centímetros de distância do bolo fecal, foram significativamente menores (P < 0,01) que na pastagem A (até 20 cm), sendo que houve redução no número de larvas recuperadas nas pastagens de 53, 71, 65 e 85 %, respectivamente nos meses de abril, julho, agosto e setembro do grupo tratado em relação ao controle. sendo que o gênero Cooperia foi o mais prevalente (59,96 %). As médias mensais de peso foram maiores significativamente no grupo B (P < 0,05), sendo que houve diferença no ganho de peso entre os grupos tratado e controle nos meses de junho, julho, agosto e setembro de 21, 13, 8,5 e 20 %. As contagens de ovos por gramas de fezes (OPG) foram obtidas pelas técnicas de Gordon & Whitlock, modificada por Lima e de Wisconsin, de Cox & Todd, modificada por Ito e apresentaram diferenças para valores de contagens de ovos por gramas entre grupo tratado e controle (P<0,05). Foi observada redução significativa nos valores da contagem no grupo tratado obtidos pela técnica de Gordon & Whitlock nos meses de maio, junho, julho e agosto de 35, 46, 36 e 30 % respectivamente e redução não significativa no mês de setembro de 26 %. E os dados obtidos pela técnica de Wisconsin houve redução significativa nos meses de junho, julho e agosto respectivos de 58, 47 e 51 % no grupo tratado em relação ao controle e redução não significativa nos meses de maio (26 %) e setembro (25 %). Pode se concluir que a aplicação de péletes de alginato de sódio contendo o fungo nematófago D. flagrans é efetiva no controle de larvas infectantes de bovinos.
22

Biological control of gastrointestinal nematodes of small ruminants, using Bacillus thuringiensis (Berliner) and Clonostachys rosea (Schroers).

Baloyi, Mahlatse Annabella. January 2011 (has links)
Gastrointestinal nematode parasites cause great losses in the production of small ruminants through reduced productivity and the cost of preventive and curative treatments. Because of the threat of anthelmintic resistance, biological control of sheep nematodes has been identified as an alternative to anthelmintic drugs. Bacillus thuringiensis (Bt) (Berliner) and Clonostachys rosea (Schroers) have been widely studied as biocontrol agents. B. thuringiensis has been used for the biocontrol of insects and C. rosea has been successfully used as biocontrol agent of Botrytis cinera (De Bary) in plants. B. thuringiensis and C. rosea strains were isolated from soil collected from the Livestock Section at Ukulinga Research Farm, University of KwaZulu Natal, Pietermaritzburg. Twenty-five strains of Bt and 10 strains of C. rosea were successfully isolated. The Bt colonies were identified by their circular, white, flat and undulate character, and the gram-positive and rod-shaped endospores. C. rosea was identified by white colonies on Potato-dextose agar and the characteristic conidiophores, which were branched and showed phialides at the tips. In vitro screening of the isolates was undertaken to select the best isolates. The isolates that caused significantly greater mortality were Bt isolate B2, B10 and B12 and C. rosea isolates P1, P3 and P8. These isolates caused substantial nematode mortality in both faeces and water bioassay. Nematode counts were reduced by 28.5% to 62% and 44% to 69.9% in faecal bioassay for Bt and C. rosea, respectively. In the water bioassay, nematode counts were reduced by 62% to 85% for Bt and by 62.7% to 89.3% for C. rosea. The best inoculum level at which the best isolates were most effective, and the optimum frequency of application were determined. The trial was conducted using bioassays with faeces and water. Inoculum levels of 10(6), 10(8), 10(10), 10(12) spores ml-1 for Bt and 10(6), 10(8) and 10(10) conidia ml-1 for C. rosea was used in the faecal bioassay. The inoculum levels tested in water bioassay were 10(6), 10(8), 10(10) and 10(12) spores ml-1 for Bt and 10(9), 10(10), 10(11), 10(12) conidia ml-1 for C. rosea. In the faecal bioassay, B2 was the most effective Bt isolate at an inoculum level of 10(10) spores ml-1. Isolate P3 was the best C. rosea isolate at 10(8) conidia ml-1. In the water bioassay, Isolate P3 caused a mortality of 85% at inoculum levels of 10(9), 10(10) and 10(11) conidia ml-1. The performance of biological control agents in the field is sometimes inconsistent. Combining different biocontrol agents may be a method of improving their reliability and performance. However, the combination of most of the isolates was antagonistic, with efficacy less than that of either individual biocontrol agent. In particular, Isolate P3 was more effective when used alone than when combined with any other isolates. Therefore, the combination of biocontrol agents does not always result in synergistic interaction. There were some additive interactions between two bacterial isolates, and with one bacterial and fungal combination. The effect of feeding the best of the biocontrol agents, or diatomaceous earth (DE), was evaluated in sheep. Two doses of Bt (1g and 2g kg-1BW) and C. rosea (1g kg-1BW) reduced the numbers of L3 nematode larvae in sheep faeces. The DE product (at 15% of feed) also reduced L3 numbers but it was less effective than either the Bt or the C. rosea products. Nematode counts were reduced by 74.6%, 75.1%, 84.6%, 68.5% and 27.5% for Bt 1g kg-1BW, Bt 2g kg-1BW, C. rosea (1g kg-1 BW), DE and control, respectively. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

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