Thesis (M.A.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 58-61). Also available via Humboldt Digital Scholar.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 129-143). Also available via the Internet.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 44-45). Also available on the World Wide Web.

This thesis deals with the role of species traits in predator-prey interactions and food web structure. I conducted laboratory experiments with predatory aquatic insects and their prey to reveal the traits determining who eats whom in small standing waters. I also focused on the possibility of incorporating the observed dependence of predator-prey interactions on body mass into existing food web models. Further, I developed a simple simulation model to explore the consequences of body mass dependent feeding and dispersal for food web assembly. Last, I show that four common methods for sampling aquatic insects differ in their selectivity, especially on the basis of body mass of sampled insects. In conclusion, I combined laboratory experiments, field work and mathematical models to evaluate the importance of body mass and other species traits, such as foraging behaviour and microhabitat selectivity, in predator-prey interactions and explored selected food web level consequences.

O presente trabalho teve como objetivo fazer um estudo taxonômico da fauna de Plecoptera (Perlidae) da região Sul do Brasil. Nós estudamos material depositado em diferentes coleções, e também novos espécimes coletados ao longo do desenvolvimento deste trabalho. Os adultos foram capturados com puçás na vegetação das margens dos riachos e através de atração luminosa. As ninfas foram coletadas dentro de riachos com o auxílio de redes D. A genitália dos adultos foi diafanizada usando KOH. Como resultado, três novas espécies foram descritas, duas possuem novos registros de ocorrência e quatro tiveram o registro de suas distribuições ampliadas para esta região. / This work aimed to make a taxonomic study of the Plecoptera (Perlidae) fauna from southern Brazil. We studied material deposited in different collections, and also new specimens collected along the development of this work. Adults were captured with D-nets in vegetation from the banks of streams and through light attraction. Nymphs were collected in streams with a D-net. The genitalia of adults were diaphanized by KOH. The adults genitalia was cleared using KOH. As a result, three new species were described, two have new records of occurrence and four had record their distributions expanded to this region.

The incidence of parasitism by Bunodera mediovitellata in Trichoptera in Tin Can Creek was investigated. Larvae of Lepidostoma roafi had a low incidence of infection , while Psychoglypha alascensis larvae had a high incidence of infection. The encapsulation reactions of these Trichoptera larvae to internal Epon implants, and metacercariae of the parasite encysted within the silk glands, were examined in vivo to determine the details of the cellular encapsulation reactions of Trichoptera to foreign objects in both of these sites, and to determine which hemocytes are involved in the reaction. The hemocytes of larvae of P. alascensis were capable of encapsulating Epon implants within the hemocoele; the reaction took approximately twenty days longer than those of other insects that have been maintained at 20°C. The hemocytes of larvae of P. alascensis are also capable of encapsulating the metacercariae of their natural parasite B. mediovitellata in the silk glands despite the normal absence of hemocytes from the silk gland lumen. The hemocyte capsules around both the non-living and living objects was typical of the 'ordinary encapsulation reaction' described by Salt (1970). The capsule consisted of an inner layer of flattened cells which were densely packed and an outer layer of cells which were not flattened to the same extent as those of the inner layer. The hemocytes which took part in both capsules around implants and capsules around parasites were flattened elongated hemocytes which probably correspond to plasmatocytes or granulocytes. However, the production of a Summary Fate Map of free circulating hemocytes demonstrated that hemocyte types are stages in the development of a number of lines of hemocyte types. It appears that the hemocytes taking part in the encapsulation reactions belong to two of these lines of hemocyte types. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Food habits, net-spinning activity, energetics, and mercury accumulation in Hydrospsyche morosa were examined over a one year period on the South River in central Virginia. Feeding nets were observed as early as April and were widespread by May. Nets were virtually absent from late November through March. Gut content analysis revealed seasonal patterns in the consumption of various food items. From April through October, when feeding nets were widespread, detritus formed the bulk of the diet in terms of both numbers of particles and volume occupied. From November through March however, the algal component dominated in terms of numbers of particles although the detritus component still occupied a greater volume. Ivlev's preference index was employed and indicated that the seasonal differences in the relative amount of the three food types were not simply a matter of changing seston concentrations, but rather suggested a shift from a filter-feeding mode of feeding in the summer months to grazing on diatoms in the winter. H. morosa was bivoltine on the South River. The estimate of secondary production for the summer cohort was 3,246 mg AFDW/m²/yr, while the estimate for the winter cohort was 2,145 mg AFDW/m²/yr. The secondary production also was estimated for each season based on food habits to determine the impact of the observed seasonal switch in feeding habits on production and egestion rates. During the summer, the detritus component contributed most to production averaging about 50 percent. Animal and algal material contributed 30 and 20 percent, respectively. During the winter, algal material contributed most to the production, averaging just over 62 percent. Detritus also contributed during the winter averaging over 30 percent. Monthly rates of production and egestion were between 3 and 3.5 times faster during the summer. The concentrations of total mercury in seston, periphyton, and in the body tissue of H. morosa were analyzed each month. Mercury concentrations were between four and six times higher in the seston than in the periphyton. The concentration of mercury in the body tissue of H. morasa ranged from 0.14 ppm in March to over 1.20 ppm in July. Differences in Mercury concentration in the insects between seasons were significant. Regression analysis revealed a significant relationship between Hg concentration in the insects and the relative amount of detritus found in the guts. / Master of Science

Three populations of Glossosoma nigrior Banks (Trichoptera: Glossosomatidae) were compared to determine how differences in thermal regime might affect their life history as well as the growth of individuals within each population. Two populations were located in Big Stony Creek (Stations 1 and 2) while the third was located in Sinking Creek (Station 3). The thermal regimes at each station differed in their seasonal patterns of temperature change and the amount of heat accumulated annually. Aside from a brief period during the spring, Station 1 was the coolest, Station 2 was intermediate, and Station 3 (Sinking Creek) was the warmest of the three sites. Populations of G. nigrior at Stations 2 and 3 ex- hibited typical bivoltine life histories. However, the population at Station 1 was univoltine with larvae present only during the summer. Comparisons among the three summer cohorts present at each station indicated that individuals growing under cooler thermal regimes were larger and grew more rapidly than did individuals exposed to warmer temperatures. A similar pattern was observed between the winter and summer cohorts located at Stations 2 and 3; members of the winter cohort at each station attained higher final dry weights and entered the prepupal stage more rapidly than did their summer cohort counterparts. The larger body size attained by G. nigrior living under cooler thermal regimes suggests that this trichopteran is metabolically more efficient at cooler temperatures. With less of its metabolized energy being allocated for maintenance costs, a large individual may channel more energy towards reproductive efforts. The flexibility in voltinism and differing body size (and thus reproductive capacity)of each cohort are advantageous life history features that have allowed G. nigrior to inhabit areas that may be only thermally suitable for this species during certain periods of the year. This ability to adjust its life history strategy to thermal conditions of a given habitat has allowed G. nigrior to expand its geographic distribution from cool mountain streams to warm water lotic habitats. / Ph. D.

Annual energy budgets of dominant benthic macro-invertebrates were examined during November 1973 to October 1974 from the benthos of a small pond ecosystem in north-central Texas. Estimates of annual secondary production (Hynes and Coleman 1968) were Procladius s. (Diptera, Chironimidae), 2.4 g m^-2 y^-1 (13 kcal m^-2 y^-1 ); Tendipes decorus (Diptera, Chironomidae), 6.0 g m^-2 y^-1 (40 kcal m^-2 y^-1 ); Brachycercus sp. (Ephemeroptera, Caenidae), 1.9 g m^-2 y^-1 (11 kcal m^-2 y^-1). Energy metabolism was measured in the laboratory at six seasonally encountered temperatures (5, 10, 15, 20, 25, and 30 C) on an acclimatization basis, and then extrapolated to the field. Estimates of annual energy metabolism are Procladius sp., 5.0 kcal m^-2 y^-1 ; Tendipes decorus, 17.2 kcal m^-2 y^-1 ; Brachycercus sp. 40.0 kcal m^-2 y^-1.