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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.
141

What Happens after Establishment? The Indirect Impacts of the Gypsy Moth on Native Forest Caterpillar Communities

Timms, Laura 23 February 2011 (has links)
Invasive insects are considered one of the most serious threats affecting forests today; however, surprisingly little research has addressed the impacts of invasive species establishment on native forest insect communities. Such information is lacking for even the most thoroughly studied invasive forest insect, the gypsy moth. Using gypsy moth as a case study, my thesis addresses the questions: What are the ecological impacts of an exotic forest insect upon its establishment in a new community of native species? Does the community shift after the invasive establishes, and if so, what are the drivers in this realignment? I used multivariate analysis to assess native caterpillar communities collected in forest stands with and without a history of gypsy moth outbreak. I found that gypsy moth outbreak history had no significant effects on native caterpillar communities; however, current gypsy moth abundance was related to shifts in the structure of late season caterpillar assemblages. These results suggest that gypsy moth may affect native caterpillar communities through short-term mechanisms but not through long-term ecological changes. I used quantitative food webs to investigate the effects of gypsy moth on native host-parasitoid webs from the same caterpillar communities, and found that food web structure was resilient to both gypsy moth outbreak history and current abundance. The gypsy moth shared few parasitoids with native species in my study sites, none of numerical significance, thus minimizing the opportunity for enemy-mediated indirect interactions. Finally, I conducted a greenhouse experiment and found that early spring feeding by forest tent caterpillar can indirectly influence gypsy moth susceptibility to its virus, demonstrating that the complex interactions that can occur between native and exotic species do not always benefit the invader. Overall, I argue that the establishment of the gypsy moth into North American forests will not cause major changes in native caterpillar communities.
142

What Happens after Establishment? The Indirect Impacts of the Gypsy Moth on Native Forest Caterpillar Communities

Timms, Laura 23 February 2011 (has links)
Invasive insects are considered one of the most serious threats affecting forests today; however, surprisingly little research has addressed the impacts of invasive species establishment on native forest insect communities. Such information is lacking for even the most thoroughly studied invasive forest insect, the gypsy moth. Using gypsy moth as a case study, my thesis addresses the questions: What are the ecological impacts of an exotic forest insect upon its establishment in a new community of native species? Does the community shift after the invasive establishes, and if so, what are the drivers in this realignment? I used multivariate analysis to assess native caterpillar communities collected in forest stands with and without a history of gypsy moth outbreak. I found that gypsy moth outbreak history had no significant effects on native caterpillar communities; however, current gypsy moth abundance was related to shifts in the structure of late season caterpillar assemblages. These results suggest that gypsy moth may affect native caterpillar communities through short-term mechanisms but not through long-term ecological changes. I used quantitative food webs to investigate the effects of gypsy moth on native host-parasitoid webs from the same caterpillar communities, and found that food web structure was resilient to both gypsy moth outbreak history and current abundance. The gypsy moth shared few parasitoids with native species in my study sites, none of numerical significance, thus minimizing the opportunity for enemy-mediated indirect interactions. Finally, I conducted a greenhouse experiment and found that early spring feeding by forest tent caterpillar can indirectly influence gypsy moth susceptibility to its virus, demonstrating that the complex interactions that can occur between native and exotic species do not always benefit the invader. Overall, I argue that the establishment of the gypsy moth into North American forests will not cause major changes in native caterpillar communities.
143

Climate and the autumnal moth (Epirrita autumnata) at Mountain Birch (Betula pubecens ssp. czerepanovii) Treelines in northern Sweden.

Young, Amanda B. 16 January 2010 (has links)
The main objectives of this investigation were to determine the impact of climate on mountain birch (Betula pubecens ssp. czerepanovii (Orlova)) growth and to develop a regional chronology of autumnal moth outbreaks. To accomplish the objective, cores of mountain birch were taken from 21 sites in Norrbotten, Sweden. Tree-ring chronologies were developed for each site. Climatic influences were determined by correlating ring widths to climatic variables (average monthly temperature, average monthly precipitation and NAO). Outbreaks were recovered from the ring width indices using the non-host method with Scots pine (Pinus sylvestris (L.)) as the non-host. This method removes the climatic influence on growth to enhance other factors. Patterns of synchrony and regional outbreaks were detected using regression and cluster analysis techniques. The primary climatic influences on the tree ring growth of mountain birch are June and July temperatures; precipitation during October is of secondary importance. Climate explained 46% of yearly tree ring width variation. Outbreaks of the autumnal moth occur at varying time intervals depending on the scale of study. Intervals between outbreaks on the tree level are twice as long as at the plot level. On the regional scale plots within the same valley had more similar outbreak intervals and magnitudes of outbreaks. Elevation is a driver in determining the length of outbreaks and length between outbreaks. The percent monocormicity of a plot is also a determining factor of the length between outbreaks. This study is the first regional scale study on climate and outbreaks of the autumnal moth on mountain birch. The results complement research being conducted on autumnal moth larval densities and will help in modeling and assessing the effects of outbreaks with increasing climatic change.
144

The study of flower preference schemata and purchase decision-making behavior.

Lee, Lea-Fong 14 August 2003 (has links)
ABSTRACT While in the developed countries, flowers are living necessity and enjoy a sizable market, the Council of Agriculture Executive Yuan R.O.C points out that cultivation and sales of flowers are important items in the prospecting dedicated agriculture industries of Taiwan. Besides the enjoyment and appreciation the beauty of blooming by oneself , in social life flowers can perform the instrumental function of expressing wishes in the occasion of marriage, birthday, promotion, house moving, and consolation in the sickness or sadness. The study of flower preference schemata is one of the importance concepts for flower product design and development. The current research figured out different patterns of flower preference among people¡¦s mind ,through pictures of moth orchid and rose designed by the three factors of flower beauty: color, volume, and package. The distinctive flower buying behaviors of the different groups were studied consequently. In our valid sample are 696 teachers from senior high and junior high schools and elementary schools in the Kaohsiung area in Taiwan. In addition to the description and analysis on people¡¦s flower buying behavior about flower type preference, shop choice, purchase frequency, and flower-as-present purchase behavior, the major findings of the current research are as the following: (1) Confirming that there exist distinctive flower preference schemata in people mind; (2) Flower preference affect the purchase behavior; (3) Demographic variables moderate the effect of flower preference on the purchase behavior; (4) Flower attitude and demographic variables affect flower consumption behavior.
145

Germline transformation and isolation of midgut related genes from the potato tuber moth, Phthoramiaea operculella, (Lepidoptera: Gelechiidae).

Mohammed, Ahmed Mohammed Ahmed 15 November 2004 (has links)
Potato production in tropical and subtropical countries suffers from damage caused by the potato tuber moth (PTM), Phthorimiaea operculella. Development of a germline transformation system and the identification of genes that are differentially expressed within the PTM midgut are the main goals of this research. We tested three components that are critical to genetic transformation systems for insects; promoter activity, marker gene expression, and transposable element function. We compared the transcriptional activities of five different promoters, hsp70, hsp82, actin5C, polyubiquitin and ie1, within PTM embryos. The ie1 promoter flanked with the enhancer element, hr5, showed a very high level of transcriptional activity compared with the other promoters. The expression of the enhanced green fluorescent protein (EGFP) was detected under UV-illumination within the embryonic soma demonstrating that it can be used as an effective marker gene for PTM. The transpositional activities of the Hermes, mariner and piggyBac transposable elements were tested in interplasmid transposition assays. The piggyBac element was shown mobile within the embryonic soma with a transposition frequency of 4.2 X 10-5 transposition/donor plasmid. The piggyBac mobility has been enhanced by incorporating a transactivator plasmid expressing the IE1 protein from the bacoluvirus Autographa californica nuclear polyhedrosis virus. Seven transformation experiments were performed. The experiments failed to produce a transgenic PTM. The insect midgut is a rich region of molecular targets involved in food processing that could be potentially used to design a new control strategy. The suppression subtractive hybridization (SSH) method was used to identify differentially expressed genes from the PTM midgut. From this subtracted library, 2984 clones were collected and screened. Of these clones, 637 clones are candidate differentially expressed genes within the PTM midgut. Sixty-nine cDNA clones were randomly selected for DNA sequencing. Tweleve clones were selected for further analysis using RT-PCR and Northern blot techniques. Eleven of the clones resulted in positive results for midgut expression. Five clones, showing homology with insect immune peptides, were used in the challenge experiment which revealed that these cDNAs are constitutively expressed in the midgut, as well as being up-regulated due to bacterial or viral challenge.
146

Tritrophic interactions in forests direct and indirect interactions between birds, insect herbivores, and oaks /

Barber, Nicholas A. January 2009 (has links)
2 spread sheets included. Title from title page of PDF (University of Missouri--St. Louis, viewed February 8, 2010). Includes bibliographical references.
147

Kopūstinės kandies (Plutella xylostella L.) (Lepidoptera: Plutelidae) skraidymo ir kenkimo intensyvumo dinamika vasarinių rapsų ir gūžinių kopūstų pasėliuose / The Dynamics of Flight Activity and Intensity of Damage of Diamondback Moth (Plutella xylostella L.) (Lepidoptera: Plutelidae) in Rape and Cabbage Crops

Vyšniauskaitė, Sigrida 21 June 2013 (has links)
Magistrantūros studijų baigiamajame darbe pateikiami kopūstinės kandies skraidymo bei kenkimo dinamikos vasarinių rapsų ir gūžinių kopūstų pasėliuose tyrimų rezultatai. Darbo objektas – kopūstinė kandis (Plutella xylostella L.) Darbo metodai – kopūstinės kandies skraidymo dinamika tirta naudojant feromonines “delta” tipo gaudykles, 2012 m. gegužės – rugpjūčio mėnesiais, vasarinių rapsų ir ankstyvųjų bei vėlyvųjų baltagūžių kopūstų pasėliuose. Vasarinių rapsų pasėlyje buvo įrengta 12 gaudyklių (po 3 su kiekvienos rūšies feromonu), o kopūstų – po 5 gaudykles su veiksmingiausiu feromonu, į jas patekę vabzdžiai buvo registruojami kas 3–5 dienas. Tyrimams naudoti 4 skirtingos sudėties sintetiniai feromonai. Kandžių pažeidimai rapsuose buvo fiksuojami birželio 7 - liepos 11 dienomis. Apskaitos buvo atliekamos kas 3–4 dienas, 3 rendomizuotai pasirinktose vietose, patikrinant po 50 augalų. Darbo rezultatai – Tyrimų metu sugautos 617 kopūstinių kandžių. Vasariniuose rapsuose vidutiniškai 1 gaudyklei per sezoną teko 79, ankstyviesiems kopūstams – 60, o vėlyviesiems kopūstams – 19 kandžių. Rapsuose skraidymo intensyvumo pikas užfiksuotas liepos 17–20 d., ankstyvuosiuose kopūstuose liepos 11–14 d., o vėlyvuosiuose kopūstuose liepos 20–23 d. Feromonas, savo sudėtyje turintis Z11-16:Ald : Z11-16:Ac : Z11-16:OH : Z9-14:Ac (0,7:0,3:0,01:0,010) labiausiai viliojo kopūstines kandis. Su šiuo feromonu rapsuose pagauti 56 % visų kandžių. Nustatyti statistiškai patikimi efektyvumo skirtumai... [toliau žr. visą tekstą] / The master thesis presents the results of studies of dynamics of flight activity, intensity of damage of Plutella xylostella. Object of the research - Diamonback moth (Plutella xylostella L.) Method of the research – ‘Delta’ traps loaded with 4 different synthetic pheromones were used for trapping of adults of P. xylostella. The investigations were carried out in the fields of summer rape as well as early and later types of cabbages during May to August in 2012. Twelve traps (by three with each pheromone) were used in summer rape; meanwhile five traps were equipped in cabbage crops and each of them was loaded with the best pheromone. The traps were visited every 3–5 days and trapped insects were registered. The damage by the Diamonback moth was registered in summer rape from 7 of June to 11 of July. Accountings were done in 3 random places checking 50 plants each 3–4 days during the study. The results of the research – The number of captured individuals of P. xylostella during the study has amounted 617. The highest activity of moths has been registered in rape i.e. on the average 79 specimens have been caught per one trap during the season, while the lower activity has been observed in early cabbages reaching 60 specimens and finally the lowest one attributing to later maturing types of cabbages which numbered 19 specimens. The peak of activity was registered from 17 to 20 July in rape, from 11 to 14 July in early cabbages and from 20 to 23 July in later maturing... [to full text]
148

Development of a Semiochemical-based Monitoring System for Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in Canola in Alberta

Miluch, Christine Unknown Date
No description available.
149

Enhanced pest management of the Douglas-fir tussock moth, Orgyia pseudotsugata (Lepidoptera: Lymantriidae)

Thorne, Christine M. 08 December 2009 (has links)
The incidence of baculovirus disease in susceptible insect hosts may be used to estimate future host population sizes and estimate the relative defoliation of these populations for economically important insects. We developed an Enzyme-linked immunosorbent assay (ELISA) that was specific to two native baculovirus pathogens of the Douglas-fir tussock moth (DFTM), that was more sensitive and accurate (R2=0.99) than microscopic counts of virus polyhedron inclusion bodies, and more accurate than PCR or Southern hybridization for the direct detection of baculovirus disease. We also developed a field-based "dipstick" assay that was sensitive enough to detect virus disease prior to host mortality and did not require virus purification from macerated insect tissues, supporting its use for on-site field surveys. Finally, we used ELISA to establish, for the first time, a method to detect persistent sublethal baculovirus infections. Our work may contribute to more accurate understanding of the incidence and influence of persistent sublethal infections on insect hosts.
150

Development of a Semiochemical-based Monitoring System for Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in Canola in Alberta

Miluch, Christine 11 1900 (has links)
Studies focused on developing a semiochemical-based monitoring system for Plutella xylostella (L.) using sex pheromone and Z3-hexenyl acetate. A commercially available pheromone trapping system was used to capture male moths at sites in Alberta in 2007 and 2008. Larval sampling occurred every two weeks after the first males were captured. Male moth capture was predictive of larval density on individual sample dates during the growing season. The predictive capability of pheromone-baited trap capture was not in direct proportion to population density and was inconsistent. Modifications to the trapping system were tested to improve attractiveness. Adding Z3-hexenyl acetate at various doses to pheromone did not improve the attractiveness to males over pheromone alone and did not attract significant numbers of females when tested at various times during the flight season. Trap height and colour did not influence male capture. Pheromone dose and lure type did influence male moth capture in traps. / Plant Science

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