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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.
11

An investigation into the detection of sugarcane African stalk borer (Eldana saccharina Walker (Lepidoptera : Pyralidae)) using hyperspectral data (spectroradiometry).

Mokhele, Tholang Alfred. January 2009 (has links)
The South African Sugarcane production is one of the world’s leading sugarcane (Saccharum spp. Hybrid) producers. However, in recent years Eldana saccharina Walker has been the most destructive pest in South African sugarcane production, causing great crop loses per annum and is the most important factor limiting sugarcane productivity. The pest has been monitored using a traditional visual approach whereby a representative sample of stalks is taken from a field and split longitudinally to assess damage and count the number of E. saccharina larvae and pupae. However, this approach is time-consuming, labour intensive and sometimes biased as only easily accessible areas are often surveyed. In order to investigate a more economical but equally effective survey methodology, this study aimed to determine the potential of using hyperspectral remote sensing (spectroradiometry) for identifying sugarcane attacked by E. saccharina. A hand-held spectroradiometer ASD Field Spec® 3 was used to collect leaf spectral measurements of sugarcane plants from a potted-plant trial taking place under shade house conditions at the South African Sugarcane Research Institute (SASRI). In this trial, nitrogen (N) and silicon (Si) fertilizers were applied at known levels to sugarcane varieties. Varieties were either resistant or intermediate resistant or susceptible to E. saccharina attack. In addition, watering regimes and artificial infestation of E. saccharina were carefully controlled. Results illustrated that severe E. saccharina infestation increased spectral reflectance throughout the whole spectrum range (400 – 2500 nm) and caused a red-edge shift to the shorter wavelength. Eldana saccharina stalk damage was also linearly related to modified normalized difference vegetation index (mNDVI) using R2025 and R2200 (R2 = 0.69). It was concluded that hyperspectral data has a potential for use in monitoring E. saccharina in sugarcane rapidly and non-destructively under controlled conditions. A followup study is recommended in field conditions and using airborne and/or spaceborne hyperspectral sensors. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2009.
12

Identification and characterization of glyphosate-resistant common ragweed

Pollard, Justin Michael. January 2007 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 10, 2009) Includes bibliographical references.
13

Developing an IPM program to control the carpenterworm moth and poplar-and-willow borer in irrigated hybrid poplars

Hannon, Eugene Russell, January 2006 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references.
14

Aspects of chemical control of the old house borer, Hylotrupes bajulus (L.) (Coleoptera: Cerambycidae) /

Dodson, Bonny Lynn, January 1987 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1987. / Vita. Abstract. Includes bibliographical references (leaves 42-47). Also available via the Internet.
15

A Manual and Tutorial for the Proper Use of an Increment Borer

Grissino-Mayer, Henri D. January 2003 (has links)
An increment borer is the primary tool used to collect samples for dendrochronological analyses. These are precision instruments and users should be trained in their proper use, care, and maintenance. In this paper, I describe the various parts of an increment borer and how to keep these in working condition. I provide details on how to sharpen an increment borer, properly core a tree, check for core compression ("jamming"), extract the core, and store the core for transport. I provide tips on how to clear a jammed borer and remove a borer stuck in a tree. An important topic concerns the effects of boring on trees. The majority of studies indicate that conifers are minimally affected by both fungal decay and discoloration, whereas certain hardwood species can sustain major internal damage. Plugging the holes created by coring is unnecessary.
16

The establishment of in vitro screening methods for evaluating the susceptibility of sugarcane (Saccharum spp. hybrids) to the fungal disease, smut (causal agent : Ustilago scitaminea H. and P. Sydow) and the stalk borer, Eldana saccharina Walker (Lepidoptera : Pyralidae).

Devnarain, Natrisha. January 2010 (has links)
The fungal disease smut (causal agent: Ustilago scitaminea H. & P. Sydow) and stalk borer Eldana saccharina Walker place major constraints on sugarcane agriculture in South Africa. The best approach for management is the introduction of resistant cultivars; however, conventional field-based screening for pest and disease resistance is a lengthy process. This study evaluated in vitro techniques combined with artificial inoculation of 12 week old in vitro plantlets and 8-10 week old embryogenic calli as rapid screening methods. Preliminary investigations were conducted on cultivars with known field ratings to smut and E. saccharina: NCo376, N26 and N39; and 5 „test‟ cultivars, whose identities were undisclosed until completion of experiments, were used to assess the accuracy of protocols. Infective U. scitaminea sporidia generated from teliospores, were used as inocula. Development of a callus protocol was unsuccessful due to sporidial and mycelial overgrowth, despite addition of a contact fungicide, Dithane M-45® (0.025 g/l) and a biocide/fungicide, PPMTM (5 ml/l), to media. Plantlet inoculation by injection, 1 cm above the apical meristem, resulted in 12% and 20% of smut susceptible NCo376 plantlets producing smut whips after 5 weeks when inoculated with 1 x 106 and 1 x 109 sporidia/ml, respectively. Smut whip production in 5 of the 8 (63%) cultivars inoculated with the lower sporidial concentration correlated with their field resistance ratings. In addition, whips harvested from in vitro plantlets were a valuable source of aseptic teliospores for future research. Ongoing work involves inoculation of NCo376 calli with such teliospores and maintenance on medium with PPMTM - emergence of whips from plantlets remains to be assessed. The E. saccharina screening protocol involved surface decontamination of eggs with 1% sodium hypochlorite (NaOCl) for 15 min. Feeding bioassays were conducted by placement of first instar larvae on in vitro plantlets and calli for 3 and 2 weeks, respectively. Larval mass, length and percentage infestation were recorded. Although greater larval size was expected in susceptible compared with resistant cultivars, the results did not support this. Significant differences in plantlet infestation were observed between susceptible (94-98%) and resistant (72-86%) lines. No significant differences were found in the callus feeding bioassay. However, a 24 h callus choice bioassay which investigated larval preference between callus genotypes compared with NCo376, showed significant differences and correctly discerned cultivar susceptibility according to field ratings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
17

The response of lepidopteran pests to commercialised Bt maize in South Africa / Jakobus Gideon Venter

Venter, Jakobus Gideon January 2015 (has links)
Bt maize expressing Cry1Ab was approved for release in South Africa for control of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) in 1998. During 2012, a stacked Bt maize event, expressing Cry2Ab2 + Cry1A.105, was also approved for control of these abovementioned pests. The aim of this study was to determine the effects of two Bt maize events expressing Cry1Ab (MON810 and Bt11) and a Bt maize event expressing Cry2Ab2 + Cry1A.105 (MON89034) on selected lepidopteran non-target pest species and certain lepidopteran stem borer species in South Africa. Results from previous studies and this study will provide information regarding efficacy of Bt maize against pests which have not been evaluated yet. Insects with significance in maize agro-ecosystems in South Africa as well as the rest of Africa, were prioritised and laboratory bioassays were conducted to evaluate the effect of Bt maize against these selected target and non-target pest species. Studies were conducted on three stem borers C. partellus, Eldana saccharina and Sesamia calamistis and three nontarget lepidopteran pest species Agrotis segetum, Helicoverpa armigera and Spodoptera exempta. Results showed that MON810 maize was not effective against A. segetum larvae feeding on maize seedlings. Differential levels of survival were observed between two A. segetum populations on MON89034 with a population from Polokwane showing survival on the stacked maize event. No S. exempta 1st instar larvae survived on MON810 and MON89034 but 3rd instar larvae survived on MON810 maize. Helicoverpa armigera larvae survived on ears of MON810 maize plants but not on events MON89034 or Bt 11. Results further indicated that C. partellus larvae were highly susceptible to these three Bt maize events. Larval survival of S. calamistis was recorded for larvae feeding on MON810 and Bt11 maize ears but not on MON89034 maize ears. Bt maize during the vegetative growth stages therefore effectively controlled C. partellus, S. calamistis and E. saccharina but the latter two species was not effectively controlled when feeding on ear tissue. This study provides important information on the effects of Bt maize on the most important non-target pest species of maize in sub-Saharan Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
18

The response of lepidopteran pests to commercialised Bt maize in South Africa / Jakobus Gideon Venter

Venter, Jakobus Gideon January 2015 (has links)
Bt maize expressing Cry1Ab was approved for release in South Africa for control of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) in 1998. During 2012, a stacked Bt maize event, expressing Cry2Ab2 + Cry1A.105, was also approved for control of these abovementioned pests. The aim of this study was to determine the effects of two Bt maize events expressing Cry1Ab (MON810 and Bt11) and a Bt maize event expressing Cry2Ab2 + Cry1A.105 (MON89034) on selected lepidopteran non-target pest species and certain lepidopteran stem borer species in South Africa. Results from previous studies and this study will provide information regarding efficacy of Bt maize against pests which have not been evaluated yet. Insects with significance in maize agro-ecosystems in South Africa as well as the rest of Africa, were prioritised and laboratory bioassays were conducted to evaluate the effect of Bt maize against these selected target and non-target pest species. Studies were conducted on three stem borers C. partellus, Eldana saccharina and Sesamia calamistis and three nontarget lepidopteran pest species Agrotis segetum, Helicoverpa armigera and Spodoptera exempta. Results showed that MON810 maize was not effective against A. segetum larvae feeding on maize seedlings. Differential levels of survival were observed between two A. segetum populations on MON89034 with a population from Polokwane showing survival on the stacked maize event. No S. exempta 1st instar larvae survived on MON810 and MON89034 but 3rd instar larvae survived on MON810 maize. Helicoverpa armigera larvae survived on ears of MON810 maize plants but not on events MON89034 or Bt 11. Results further indicated that C. partellus larvae were highly susceptible to these three Bt maize events. Larval survival of S. calamistis was recorded for larvae feeding on MON810 and Bt11 maize ears but not on MON89034 maize ears. Bt maize during the vegetative growth stages therefore effectively controlled C. partellus, S. calamistis and E. saccharina but the latter two species was not effectively controlled when feeding on ear tissue. This study provides important information on the effects of Bt maize on the most important non-target pest species of maize in sub-Saharan Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
19

Coleobrocas (Insecta: Coleoptera) associadas à madeira de Tectona grandis Linn. f (Lamiaceae) / Borers (Insecta: Coleoptera) in wood of Tectona grandis Linn. f (Lamiaceae)

Moura, Rogério Goularte 16 January 2008 (has links)
No estado de Mato Grosso, a área reflorestada com Tectona grandis é de aproximadamente 43 mil hectares. A crescente demanda por madeira de reflorestamento vem impulsionando a expansão de novas áreas. Neste contexto, é imprescindível estudos e informações sobre esta cultura no Brasil. Este trabalho teve como objetivo principal identificar as espécies de coleobrocas que atacam a madeira de T. grandis com casca e sem casca, em reflorestamento localizado no Município de Rosário Oeste, estado de Mato Grosso. O delineamento experimental adotado foi fatorial 2x4 com dois tratamentos (toretes com casca e toretes sem casca) e quatro tempos de armazenamento (30, 60, 90 e 120 dias). Neoclytus pusillus (Cerambycidae) e Xyleborus ferrugineus (Scolytidae) foram as espécies mais importantes nas madeiras com casca e Xyleborus ferrugineus (Scolytidae), Neoclytus pusillus (Cerambycidae), Micrapate sp., Xyloperthella picea e Bostrychopsis uncinata (Bostrichidae) nas madeiras sem casca. / This paper evaluates the species of wood borers occurring on cut wood with bark and debarked wood of Tectona grandis. The statistical model was carried out in a completely randomized design. The treatments were defined in a 2x4 factorial array with two treatment (logs with bark and logs debarked) and four storage times (30, 60, 90 and 120 days), and the data were analyzed through the statistical program SAS. The most common species in logs with bark were Neoclytus pusillus (Cerambycidae) and Xyleborus ferrugineus (Scolytidae) and the most important ones in debarked logs were Xyleborus ferrugineus (Scolytidae), Neoclytus pusillus (Cerambycidae), Micrapate sp., Xyloperthella picea and Bostrychopsis uncinata (Bostrichidae).
20

Coleobrocas (Insecta: Coleoptera) associadas à madeira de Tectona grandis Linn. f (Lamiaceae) / Borers (Insecta: Coleoptera) in wood of Tectona grandis Linn. f (Lamiaceae)

Rogério Goularte Moura 16 January 2008 (has links)
No estado de Mato Grosso, a área reflorestada com Tectona grandis é de aproximadamente 43 mil hectares. A crescente demanda por madeira de reflorestamento vem impulsionando a expansão de novas áreas. Neste contexto, é imprescindível estudos e informações sobre esta cultura no Brasil. Este trabalho teve como objetivo principal identificar as espécies de coleobrocas que atacam a madeira de T. grandis com casca e sem casca, em reflorestamento localizado no Município de Rosário Oeste, estado de Mato Grosso. O delineamento experimental adotado foi fatorial 2x4 com dois tratamentos (toretes com casca e toretes sem casca) e quatro tempos de armazenamento (30, 60, 90 e 120 dias). Neoclytus pusillus (Cerambycidae) e Xyleborus ferrugineus (Scolytidae) foram as espécies mais importantes nas madeiras com casca e Xyleborus ferrugineus (Scolytidae), Neoclytus pusillus (Cerambycidae), Micrapate sp., Xyloperthella picea e Bostrychopsis uncinata (Bostrichidae) nas madeiras sem casca. / This paper evaluates the species of wood borers occurring on cut wood with bark and debarked wood of Tectona grandis. The statistical model was carried out in a completely randomized design. The treatments were defined in a 2x4 factorial array with two treatment (logs with bark and logs debarked) and four storage times (30, 60, 90 and 120 days), and the data were analyzed through the statistical program SAS. The most common species in logs with bark were Neoclytus pusillus (Cerambycidae) and Xyleborus ferrugineus (Scolytidae) and the most important ones in debarked logs were Xyleborus ferrugineus (Scolytidae), Neoclytus pusillus (Cerambycidae), Micrapate sp., Xyloperthella picea and Bostrychopsis uncinata (Bostrichidae).

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