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作者 Maknojia, Shahnaz Rahim
書名 Bacterial diversity and nutritional significance of the surface microlayer in Anopheles gambiae (Diptera: Culicidae) larval habitats
說明 164 p
附註 Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0056
Adviser: Edward D. Walker
Thesis (Ph.D.)--Michigan State University, 2006
Anopheles gambiae and Anopheles funestus are well known vectors of human malaria in subSaharan Africa. The abundance of the adult stages of these mosquitoes necessarily depends on the number and productivity of the larval habitats. Even though these habitats are the source of these competent vectors, little is known about the productivity for larva habitat. Larvae are specialized gathering-filtering feeders and feed on materials in the surface microlayer which is enriched with microorganisms and other materials relative to subsurface zones of the water column
In this study the bacterial composition of the surface microlayer, and its significance to larval nutrition and growth was examined. Removal of the surface microlayer at regular intervals resulted in decreased survival of larvae, prolonged developmental time to pupation, and produced adults with lower body mass. Supplementations of the surface microlayer from habitats with no larval grazing improved larval growth, shortened larval developmental time, and produced adults with higher total mass. Importance of heterotrophic bacteria in relation to larval nutrition was studied and it was observed that larvae grew, molted, and achieve metamorphosis to pupation when heterotrophic bacterial growth was enhanced by addition of glucose, but larval survival rate and total adult emergence was very low compared to sunlit treatments rich in algae. Glucose addition to sterilized habitats resulted in complete growth failure of larvae
Effects of larval grazing pressure on bacterial communities was studied with two different soil types using 16S rDNA sequence library construction and Terminal Fragment Length Polymorphism (TRFLP) analysis. Community shifts were observed either by presence or absence of certain taxa, or changes in the frequencies of certain taxa, as represented by the sequence data
Finally, a culture-independent survey of bacteria present in the surface microlayer of natural An. gambiae and An. funestus larval habitats in western Kenya was undertaken. Overall both An. gambiae and An. funestus larval habitats were very diverse and revealed few dominant and many uncommon taxa. LIBSHUFF analysis revealed that these communities were statistically different, but Principal Component Analysis (PCA) on the sequence data and TRFLP analysis did not show any significant clustering of specific habitats. Therefore, there was no clear evidence supporting habitat segregation based on bacterial community structure
School code: 0128
Host Item Dissertation Abstracts International 68-01B
主題 Biology, Entomology
Alt Author Michigan State University
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