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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.
91

Interactions between insect pests and the size, quality and gas exchange activity of cabbage plants (Brassica oleracea)

Langan, Anthony Mark January 1998 (has links)
No description available.
92

Host use and foraging in the parasitic plant Cuscuta subinclusa.

Kelly, Colleen Kay. January 1988 (has links)
Foraging theory predicts active responses by organisms upon encounter with a resource, as opposed to the passive responses of differential survivorship and growth. Stems of the parasitic plant Cuscuta subinclusa invest in resource acquisition (coil) relative to host quality in a way predicted by the marginal value theorem (MVT) in that: (1) stem coiling, the necessary antecedent and determinant of resource uptake, precedes exploitation of host materials; and (2) mean coiling on a host species is proportional to: (a) mean growth/haustorium, (b) mean biomass accumulation over the season, and (c) mean parasite growth/host individual. Coiling is correlated with growth/host individual for the 5 native host species examined, but not when a non-native species is added to the model, suggesting coiling response is a result of natural selection. Preliminary evidence indicates that coiling in C. subinclusa is induced by host bark chemicals. Resource-poor stems of C. subinclusa are more likely to coil, and coil more, than resource-rich stems, thus nutritional state of the parasite as well as host value affects foraging responses. Evidence from other experiments suggests that the costs of growth, or "search costs", may affect host acceptability. When water is readily available, transplanted C. subinclusa stems are less likely to coil on branches of Platanus racemosa. During the dry season, when cellular expansion is difficult, all p. racemosa branches were coiled upon. Large parasites are more likely to over-winter and set seed a second season, and parasites that start from over-wintered tissue are significantly larger at flowering than are those that have started from seed. Seed set is correlated with parasite size, thus linking foraging response and fitness of the plant. C. subinclusa's foraging response does not, however, predict population level patterns of host use. The principal determinant of host use by C. subinclusa is average proximity of a species to Malosma laurina. Parasite individuals infest many host species each season, but initially establish, set most seed, and over-winter only on M. laurina. Individual response of C. subinclusa contributes to the model of host use only after proximity to M. laurina is accounted for, suggesting that mechanisms maximizing exploitation of a host take effect after contact between host and parasite.
93

Dual mycorrhizal symbiosis in Salix : the role of arbuscular mycorrhizal fungi in an ectomycorrhizal genus

Haigh, Joanna Marie January 2000 (has links)
No description available.
94

The role of fimbriae and flagella in the pathogenesis of Salmonella enteritidis phage-type 4 infections

Allen-Vercoe, Emma January 1999 (has links)
No description available.
95

The susceptibility to malathion of Metopolophium dirhodum (Homoptera:Aphididae), Aphidius rhopalosiphi (Hymenoptera:Aphidiidae) and Coccinella septempunctata (Coleoptera:Coccinellidae) in a tritrophic context

Tilahun, Dejene A. January 2001 (has links)
No description available.
96

Larval competition and cannibalism in the Indian meal mouth, Plodia interpunctella

Reed, Douglas James January 1998 (has links)
No description available.
97

Studies towards synthetic receptors for small peptides and sugars

Flack, Stephen Sean January 1995 (has links)
No description available.
98

Studies towards a novel synthetic receptor for small peptides

Waymark, Christopher Peter January 1995 (has links)
No description available.
99

Comparative population dynamics of wild and reared pheasants (Phasianus colchicus)

Woodburn, Maureen I. A. January 1999 (has links)
No description available.
100

Insecticide tolerance of aphids and their natural enemies on different cultivars of a crop

Clayson, Paul January 2001 (has links)
No description available.

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