The distribution and abundance of six bumblebee species (Bombus) and their associated flowers were studies for 12 weeks in 26 discrete subalpine meadows over the summer of 1981. Principal component analysis of flower densities identified phenological patterns of blooming and differential affinities of plants for moisture as the major contributors to flower variation among the meadows. A positive relationship between bumblebee species diversity and meadow area in the early summer and mark-recapture experiments suggested that queens are attracted to large meadows for nest establishment. After colony initiation meadow floristics govern Bombus species diversity and abundance. Results showed that: (1) mid- to late-summer bumblebee diversity, the temporal occurrence of new queens, and the densities of two species were correlated with the density of nectar producing flowers; (2) flower composition in meadows where local extinctions of at least one Bombus species occurred differed from those where all species persisted; and (3) the number of species reaching reproductive fruition was independent of bumblebee species composition. These results underscore the importance of nectar resources in Bombus colony and guild development. Multiple regression analyses were used to relate the effects of meadow size, elevation, and floristics to observed densities of Bombus flavifrons and B. rufocinctus. In mid- to late summer a significant portion of the variation in densities not explained by these variables was accounted for by densities of congenerics. In meadows where all Bombus were removed except B. flavifrons or B. rufocinctus significant positive density compensation was observed for the latter, but not the former. These results are suggestive of relationships among bumblebee densities, intensity of competition, colony ontogeny, colony reproduction, and local floristics that question both the (1) simplistic views of Bombus guild organization based on the paradigm of tongue length, corolla depth, and character displacement; and (2) the stochastic view that flowering phenologies and developmental time lags thwart resource-based guild organization.

The elemental composition within structured insect populations was tested by creating a new method to analyze how variables (survival, growth and fecundity) within a population matrix could potentially affect the stoichiometric regime of a structured population at steady state. This was done by focusing on if the growth rate hypothesis, which states that there is a linear relationship between an individual growth rate and the percent of phosphorus within the individual, works at a population level. This was analyzed by creating and combining two matrices: the matrix-population containing the variables and a matrix containing the element phosphorus and dry weight. Data from a beetle species, Chrysomela tremulae F., was used as a guideline to create eight stoichiometric generic populations, where survival, growth and fecundity were tested in each of the eight generic populations. The results showed deviations from the growth rate hypothesis, suggesting that the hypothesis does not always work within structured populations. However, more research is needed to predict exactly how this hypothesis works in populations. Overall, this new method for analyzing stoichiometry within structured populations is a useful analytical tool, but there is a need for analyzing the results from these models in a more efficient way.

Call number: LD2668 .T4 1957 G73 / Master of Science

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Judith Hough-Goldstein, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

No description available.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [78]-88).

The response to host plant variation shapes the long-term success of phytophagous insects. Two gall-forming tephritid flies, Urophora affinis and U. quadrifasciata, oviposit in flower buds of Centaurea diffusa and C. maculosa (Asteraceae). Females of both fly species chose among plants, among groups of buds on plants, and among buds. Among plant choices were correlated with buds per plant. Among bud choices corresponded to larval developmental requirements. Insect attack led to gall formation, bud abortion, and reduced seed production. Bud abortion, caused by probing females, limited gall densities. Increased densities of U. affinis females relative to oviposition sites led to more U. affinis galls, increased bud abortion, fewer U. quadrifasciata galls, and fewer seeds. A temporal refuge for seed production was observed. Plants compensated only slightly for aborted buds. Bud abortion may increase the search time between successful ovipositions. A simulation model based on this premise implied that bud abortion may dramatically reduce total gall formation. Plant quality was manipulated in an attempt to shift three population limiting factors. Plants responded to fertilization and watering with an increase in bud numbers. Except for two year-site-treatment combinations, galls per developed bud did not differ significantly between treatments. Treated plants did not differ in their propensity to abort buds. U. affinis larvae developed faster in fertilized plants. Among year comparisons showed that the density of buds available for oviposition was limited by precipitation, non-random insect attack, and, in the longer term, by the reduction in seed production due to fly attack. Bud densities, in turn, limited gall densities. / Science, Faculty of / Zoology, Department of / Graduate

Trout were introduced into a flow-through enclosure constructed in the headwaters of a small fishless stream to examine the effects of trout predation on the density, standing crop and production of lotic insect populations. Following the trout introduction, the density and standing crop of 3 of the 9 insect species examined decreased in the experimental stream study section (enclosure) while the density and standing crop of 2 insect species increased in the experimental stream section compared with the control stream section. Data on the food habits of the trout indicated that trout predation had reduced the density and standing crop of these insect populations in the experimental stream section. Competitive release was suggested as the reason for the increase in density and standing crop of the insect populations in the experimental stream section. The role of trout predation in structuring stream insect communities is briefly discussed. Production estimates of lotic species in the experimental stream section were not significantly different from those in the control section. Trout consumed only 0.4 times the mean standing crop or 9-10% of the production of prey species. However, trout were thought to be intensively grazing the available food supply. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Thesis (M.S.)--University of Tennessee, Knoxville, 2002. / Title from title page screen (viewed Feb. 26, 2003). Thesis advisor: Paris Lambdin. Document formatted into pages (viii, 87 p. : ill. (some col.), 1 col. map). Vita. Includes bibliographical references (p. 66-75).