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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.

Field studies on the biology of Aedes triseriatus (Say)

Loor, Kleber Arturo, January 1969 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Étude comparative morphologique et biologique de souches d'Aedes (Stegomyia) aegypti Linnaeus 1762 d'origines géographiques différentes

Aldighieri, Jeannine. January 1900 (has links)
Thesis (doctoral)--Université d'Aix-Marseille, 1962. / "No. d'ordre: 110." Includes bibliographical references (p. 141-146).

Ultrastructure of the melanization response of Aedes trivittatus against inoculated Dirofilaria immitis microfilariae

Forton, Keith F. January 1984 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 19-25).

An ultrastructural study of the anal papillae of aedes campestris larvae and of the hind gut of Aedes campestris and Aedes aegypti larvae

Meredith, Joan January 1971 (has links)
The basic morphology and ultrastructure of the anal papillae of a saline water mosquito larva (Aedes campestris) have been investigated under two physiological conditions: (a) normal hyperosmotic external medium and (b) dilute hyposmotic medium. The ultrastructure of these organs suggests that they are not rudimentary, but rather are made up of cells that are morphologically specialized for transport. The anal papillae appear active in both the normal and dilute media and possible functions under the two physiological conditions are discussed. No major qualitative or quantitative differences were observed with the large change in external medium. This suggests that physiologically-demonstrated adaptive changes may require only minor structural alterations. The morphology and ultrastructure of the hind gut of A. campestris larvae were compared under two physiological conditions; normal (requiring hyporegulation) and dilute (requiring hyperegulation) external medium. No differences which might be associated with hyporegulation were observed. The rectum of A. campestri s was compared to that of Aedes aegypti. The rectum in the former is composed of two regions, an anterior and posterior rectum, while in Aedes aegypti, an exclusively freshwater mosquito larva, the rectum has only a single region. The rectal epithelia in both insects studied have morphological specializations for water and ion transport, and a consideration of quantative differences suggests that the posterior rectum is unique to Aedes campestris and hence could be responsible for the ability of this species to produce hyperosmotic urine. When the posterior rectal epithelium is compared to similar transporting epithelia in previously-studied terrestrial insects, several ultra-structural differences were noted. It is suggested that the mechanism of hyperosmotic urine production in saline water insects may be different from that in terrestrial insects. Several possible mechanisms of hyperosmotic urine production are discussed. / Science, Faculty of / Zoology, Department of / Graduate

Aedes aegypti population dynamics : the effects of food availability and experimentally induced mortality of late instar larvae

Cermark, Paul M. January 1998 (has links)
The effects of food availability and selective control of late instar larvae of Aedes aegypti on preimago population structure, mortality, adult abundance, sex ratios, and size of females were examined. Food availability i an important factor in determining preimago population structure and mortality. At optimal food availability more adults emerged, females were larger and in higher proportions than at suboptimal food availability. The effects of selective control on preimago population structure and post treatment larval mortality differed with food availability. At suboptimal food availability the type of control applied had a significant effect. Simulated pathogen-induced mortality resulted in a shift of the population to late instars and temporarily reduced density dependent mortality. The findings suggest that although both pathogens and predators reduce intraspecific competition by directly killing competitors, pathogens also provide an influx of food. Compensatory mortality may result from a reduction of intraspecific competition caused by biocontrol agents.

The effects of nutrition deficiency as a causal agent of population cycling and the impact of various densities of Plagiorchis elegans on the population structure of Aedes aegypti pre-imagos /

Hartley, Bruce J. January 1996 (has links)
The effects of food availability on the population structure of Aedes aegypti in the presence and absence of Plagiorchis elegans cercariae were studied in the laboratory. Under conditions of low food availability and in the absence of the parasite, larval population levels cycled at 40 day intervals. Cycles were initiated by the periodic build-up and decline of fourth instar larvae. These major competitors for food resources appear to be responsible for the release of a cascade of events which allowed the intermittent flow through of larvae from the first to the third instar. Under both optimal and suboptimal conditions of food availability, the introduction of high densities of P. elegans cercariae resulted in a decrease in the production of adult mosquitoes. Although the parasite reduced competition by preferentially removing fourth instar larvae and hastened the development of surviving instars, such survivors were exposed to the effects of the parasite as soon as they reached the fourth instar.

Nutrition, competition and mortality : the impact of Plagiorchis elegans on the development of Aedes aegypti

Nguyen, Duyen. January 1998 (has links)
The effects of food availability and the presence of the parasite, Plagiorchis elegans, on the probability of Aedes aegypti preimagos to transform from one immature stage to the next over consecutive 24- or 48-hour periods of time were determined. Under conditions of low food availability, 24- and 48-hr transition probabilities of all larval instars, to the next were reduced. Increases in food availability reversed this process, causing significant decreases in same-stage transition probabilities. However, as transition to successive stages increased among first, second, third and fourth instars, there was concomitant significant increase in first and fourth preimago mortality. Addition of Plagiorchis elegans cercariae caused significant decreases in the 24 and 48-hour same-state probabilities for all pre-imago stages. Successive stage transitions for first, second and third instars were significantly increased while those of fourth instars and pupae were significantly decreased following exposure to the parasites. The mortality of all preimago stages significantly increased with exposure to parasite, but was highest among fourth instars and pupae. There were strong food-by-parasite interaction effects among first, second and third instars. Differences in transition probabilities increased with increasing food levels between controlled and parasite-exposed groups. The opposite was true for fourth instars and pupae. While there was no significant interactive effect between food and the presence of the parasite on pupae regardless of food concentration, this was not true for mortality probabilities among fourth instars. Significantly more fourth instars died in response to parasite exposure and there were significant interactive effects of food and parasites on the probability of fourth instars transformation to pupae over 48 hrs.

The effects of Plagiorchis noblei, Park, 1936 on the reproductive success and behaviour of adult Aedes aegypti /

Kimoro, Charles Omuoyo January 1990 (has links)
Aedes aegypti pupae were exposed to cercariae of the digenean Plagiorchis noblei in order to assess the effects of infection on the spontaneous flying activity and reproductive success of surviving adults. Infections established primarily in the thorax and abdomen of the insects (mixed infections) or in the abdomen alone. In mixed infections, as few as one or two metacercariae in the thorax reduced the spontaneous flying time of females by almost half. Such infections also reduced total egg production, the number of ovarian cycles, fecundity per cycle, as well as fertility and life span of female hosts. The fertility and life span of males was similarly affected. Purely abdominal infections reduced the life span of males and females as well as the fertility of males, but only at high intensities. Such effects on adult behaviour, reproductive success and life span may augment the known lethal effects of the parasite.

The impact of selective oviposition, egg hatchability, food availability and infection with Plagiorchis elegans on the pre-imago population dynamics of Aedes aegypti (Diptera:Culicidae) /

Schwab, Anne Elisabeth. January 2000 (has links)
Cercariae of the digenean Plagiorchis elegans cause high levels of morbidity and mortality among larvae of Aedes aegypti . The impact of this parasite on the larval population dynamics of the experimental host as mediated through intraspecific competition, egg hatchability and ovipositional preference was assessed by calculating the probability of pre-imagos to develop from one stage to the next, or to die within consecutive 24 h intervals. Attractiveness of the water to ovipositing females in a dynamic larval population was not affected by exposure to the parasite, but varied significantly over time, regardless of food abundance. In optimally fed populations, these changes were positively correlated with pupal production, but were not affected by early instar development. Most of the entomopathogenic effects of the parasite were expressed in the pupal stage. Thus, exposure to the parasite significantly reduced adult emergence, but did not greatly impair pre-imago development. Nonetheless, exposure to various levels of the parasite significantly increased mortality of all larval stages. Suboptimally fed larval populations displayed severely impaired development and produced few adults. Exposure to P. elegans increased adult production slightly, suggesting depensatory mortality. In nutritionally stressed populations, no correlation was found between biomass and ovipositional preference, but attractiveness of the water was significantly increased by the removal of individuals by pupation or mortality. Egg hatchability was not significantly affected by population structure, but varied with the nutrient content of the water. This study provides new insight into the use of parasites as agents in the biological control of mosquitoes.

The influence of experimental Plagiorchis nobeli (Trematoda: Plagiorchiidae) infections on the survival and development of Aedes aegypti /

Dempster, Shiona Jane January 1988 (has links)
No description available.

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