Tallgrass prairie restorations generally aim to reconstruct native plant assemblages altered by disturbance to a composition of species characteristic of undegraded communities the region. Most prairie restorations, however, lack large herbivores such as Bison bison and Cervus canadensis, therefore leaving herbivory to Odocoileus virginanus, other small mammals, and insects. Although insects are more abundant by comparison, it is hypothesized that their influence as ecological drivers is often obscured by fire, grazing, and climate. Previous study in remnant prairie has shown that insects eat very little of above net primary productivity (ANPP), however they can alter the forb:grass ratio in prairies. Nonetheless, studies have shown that younger plants (particularly forbs) are more susceptible to insect herbivory due to higher nitrogen (N) content and physical and chemical defenses not yet fully developed. This research used an experimental approach (insecticide application) to reducing insect abundance and ectophagy to determine whether insects preferentially feed on forbs, alter forb:grass ratios, and affect diversity and aboveground net primary productivity (ANPP) in young (1-2 y) and more established (7-8 y) restored prairies. Ectophagy measurements showed that forbs were preferred over C4 grasses. Reduced herbivory decreased diversity of forbs and sown grasses, decreased percent cover of forbs, and species richness of sown grasses, and increased evenness in the youngest prairie. Contrary to expectations, ANPP and forb:grass ratios were not affected by treatment. Nevertheless, interactions between year and restoration age were often significant, suggesting that climate variability between seasons and maturity of community may influence how insect herbivores affect restored prairie. There was a positive correlation between herbivore morphospecies richness and sown forb richness. Insect communities were also characterized in restored prairies to evaluate treatment success. Insects were collected by sweep-netting. I collected 10 orders, 83 families, and 150 morphospecies. The largest number of species present was from Hemiptera (suborder Auchenorrhyncha). Species richness decreased through time. Pesticide application reduced diversity of families. Ectophagous insect abundance and richness were impacted by treatment, but piercing-sucking herbivores (Hemiptera) did not respond to insect reduction treatment. Predator/parasitoid insects were also reduced by treatment, indicating a larger sensitivity at higher trophic levels. Like plant diversity, interactions between restoration age and year affected almost all insect variables, suggesting that insect populations are dynamic and sensitive to nearby land-use.

x, 81 p. : ill (some col.) / This study investigates how two major groups of forest pests in North America, defoliating insects and bark beetles, influenced subsequent wildfire severity in the Booth and Bear Complex Fires. A secondary goal is to ascertain whether high-resolution plot-based vegetation data are better predictors of fire severity than lower resolution historical vegetation data. General Additive Models were used with an information-theoretic approach to determine the importance of forest insect outbreaks as predictors of fire severity. The models indicate that pest outbreaks were not significant predictors of fire severity and that high-resolution plot-based vegetation data are not superior to lower resolution historical vegetation data. Elevation and weather conditions were the most important controls of severity, while low-resolution vegetation data, slope and topographic position were of secondary importance. These results suggest defoliating insect outbreaks do not appreciably increase fire severity, though this finding should be verified in the context provided by other fires. / Committee in charge: Dr. Dan Gavin, Chairperson; Dr. Andrew Marcus, Member

Orientador: Diogo Cavalcanti Cabral de Mello / Banca: Ana Paula de Moraes / Banca: Clarisse Palma da Silva / Resumo: DNAs satélites (DNAsat) são sequências usualmente repetidas centenas a milhares de vezes arranjadas consecutivamente uma à outra, enriquecidas geralmente na heterocromatina em regiões específicas ou cromossomos, tais como os cromossomos B. Neste trabalho, isolamos o primeiro DNAsat no gafanhoto Abracris flavolineata, nomeado AflaSAT-1. A sequência foi caracterizada integrando abordagem molecular, genômica e citogenética objetivando compreender a organização estrutural, evolução nos cromossomos A e B e possível atividade transcricional. O AflaSAT-1 é compartilhado entre espécies de gafanhotos, mas revelou uma evidente amplificação em A. flavolineata formando arranjos detectáveis. A sequência apresentou baixa variabilidade em nível interpopulacional; no entanto monômeros do cromossomo B (µB-DNA) da população de Rio Claro/SP exibiram maior variabilidade e quatro mutações exclusivas, refletindo a comum taxa mutacional mais elevada dos cromossomos B. A análise genômica estrutural revelou organizações distintas para o DNAsat, apresentando uma associação alternativa com outro DNAsat, nomeado AflaSAT-2. A análise cromossômica revelou que ambos os DNAsat estão interligados um ao outro formando grandes blocos nos centrômeros de quase todos os cromossomos (exceto para o menor par), e para o cromossomo B apenas um pequeno sinal centromérico foi notado em indivíduos da população de Rio Claro/SP. Nas distintas populações a distribuição cromossômica do AflaSAT-1 revelou variabilidade, como ausência de algumas marcas, blocos adicionais e também heteromorfismo, a qual se correlacionou com a estimativa de número de cópias, sugerindo uma dinâmica de expansão ou eliminação de repetições. Finalmente, a constitutiva atividade transcricional de AflaSAT-1 foi observada nos distintos tecidos de adultos, e em distintas fases de desenvolvimento, tanto em indivíduos portadores e não portadores de cromossomo B / Abstract: Satellite DNAs (satDNA) are sequences usually repeated hundred to thousand times tandemly arrayed, enriched in heterochromatin from specific region or chromosomes, including B chromosomes. Here, we isolated the first satDNA in the grasshopper Abracris flavolineata, named AflaSAT-1. The sequence was characterized by integration of cytogenetic, molecular and genomics approaches, aiming to understand the structural organization, evolution in A and B chromosomes and possible transcriptional activity. The AflaSAT-1 is shared with other grasshopper species, but it was evidently amplified in A. flavolineata forming detectable clustered arrays. AflaSAT-1 presented low variability at interpopulational level; but monomers from B chromosome observed in individuals from Rio Claro/SP were more variable presenting four exclusive mutations, reflecting the common higher mutational rate in this chromosome. Genomic structural analysis revealed distinct organization for the satDNA, with its alternative association with other satDNA, named AflaSAT-2. The chromosomal analysis showed that both satDNAs were also interglimed to each other, forming large blocks in centromeres of almost all chromosomes (except the smallest pair), but in the B chromosome only a small centromeric signal was noticed in individuals from Rio Claro/SP. Chromosomal distribution for AflaSAT-1 revealed variability, at populational level, with absence of marks, additional clusters and heteromorphism. This variation was coincidentally followed by variability in copy number, suggesting dynamic expansion or elimination of repeats. Finally, AflaSAT-1 was constitutively transcriptionally active in five tissues of adults, in distinct life cycle phases, and both in carrier and non-B chromosome carriers / Mestre

No description available.

No description available.

Nudaurelia co virus (Nco V) is a small RNA virus belonging to the Family Tetraviridae. Nco V was successfully isolated from field collected larvae of the pine emperor moth, Nudaurelia cytherea capensis. By polyacrylamide gel electrophoresis-it was possible Jo determine the size of the capsid proteins. Anti-NcoV antiserum was raised by inoculating a rabbit with purified virus. RNA was extracted from the purified virus using a phenol\chloroform extraction procedure. It was possible to separate the viral RNA into its constituent species using sucrose density gradient centrifugation. The sizes of both species of RNA was accurately determined by agarose gel electrophoresis. These sizes corresponded to the replicative form of the RNA which was extracted from infected host tissue. The absence of a poly(A) tract on the RNA was shown through poly(U) sepharose chromatography. Cell-free translation of the viral RNA elucidated the sizes of proteins encoded in vitro in a rabbit reticulocyte lysate system. Optimal conditions for in vitro translation of Nco V were determined for a range of conditions. Immunoprecipitaion of viral encoded proteins with anti-Nco V antiserum suggested that the putative coat protein of the virus was encoded by RNA 2, as a precursor polypeptide which underwent posttranslational cleavage. Reverse transcription - polymerase chain reaction (RT -PCR) was used to successfully produce a radiolabelled probe which could detect dot-blotted viral RNA. The efficacy of this probe in detecting the presence of Nco V RNA in infected tissue was also tested.

No description available.

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), are haplodiploids. Virgin females produce sons parthenogenetically but must be mated to produce daughters. As a result, primary and secondary (adult) sex ratios can diverge from the 1:1 ratio commonly observed in diploid systems. Field studies were conducted to examine the spatial distribution of WFT on two greenhouse crops, Bell peppers, Capsicum annuum (Linn.) and Long English cucumbers, Cucumis sativus (Linn.) to determine if there was a correlation between sex ratio and density. Leaf and flower samples were taken weekly. All adult and immature WFT were counted and sex of adults determined. Yellow sticky traps were used to monitor density and sex ratio of the dispersing adult population. Lab studies were also done to investigate if male availability affected the sex ratio and number of offspring produced by individual females. Laboratory experiments were done to assess the effects of sperm availability and maternal age on sex ratio of progeny produced. On both crops, 84 to 95 % of adult WFT in flowers were females and most larvae (> 85 %) were found on leaves. Male WFT were rare on all plant parts even when caught in high numbers on traps. Approximately 75 % of females found on plants in the greenhouse were mated. Most (70 - 90 %) WFT on traps at low densities (< 200 individuals/trap) were males. This suggests that WFT populations are initiated by virgin females that likely overwintered as pseudopupae in the greenhouse. These females initially produce only sons, and may have to wait for these to emerge before they mate and produce daughters. As WFT density within a greenhouse increases, females are probably mated soon after emergence. Sex ratio of adults on traps becomes more female biased as density increases within a greenhouse. Heavily female biased (> 65 %) sex ratios were found on traps at high population densities (> 200 individuals/trap). Sex ratio of adults on traps remained male biased in the pepper greenhouse (WL) where the population density of WFT remained low. Information regarding within-plant distribution of thrips is essential for population monitoring and control. Used together, regular examination of flowers and counts of adults on sticky traps allow quick detection of potential "hot spots" of WFT density. Sex ratio and density are highly correlated. Sex ratio of the dispersing adult population is a good predictor of outbreak potential of the extant WFT population. Two WFT predators found in greenhouses were also monitored to document their effects on WFT population density and sex ratio. Mass introductions of the predatory mite, Amblysieus cucumeris, did not successfully control WFT in most greenhouses monitored. A natural infestation of pirate bugs, Orius tristicolor occurred in the only pepper house monitored. WFT density remained low throughout the growing season. O. tristicolor shows promise for future use in integrated pest management programs designed to control F. occidentalis in commercial greenhouses. Lab studies showed that sex ratio of offspring produced by mated females was influenced by sperm supply and maternal age. Mated females produced sons and daughters which suggests that females control sex of offspring produced through selective fertilization. Once mated, two-thirds of offspring produced are females. Older females produced fewer daughters than younger females. A principle conclusion from this study is that sex ratio of the WFT population within a greenhouse can be used to predict future population dynamics. Male availability may be the most important factor affecting the number of daughters produced by individual females which in turn may determine the potential of WFT populations to increase. / Science, Faculty of / Zoology, Department of / Graduate

Apanteles rubecula is a solitary insect parasite of Pier is rapae (small cabbage white butterfly, imported cabbageworm). The parasite has been successfully introduced to Australia and Vancouver, Canada but has failed to become established at other North American release sites. This practical problem illustrates a fundamental aspect of insect ecology. The seasonal biology of insects is interpreted here as an interaction of responses to ambient conditions. Emphasis centers on the rates at which life history phenomena occur and the importance of the insect's biological chronometers on the outcome of its ecological relationships with its host and its local climate. Comparisons are made between Canberra, Australia and Vancouver, Canada. The parasite's developmental response to temperature is similar in Canberra and Vancouver but the host response differs. Canberra A. rubecula have a longer generation time relative to the host at low temperatures, but shorter generation times at higher, midseason temperatures. Vancouver parasites always have faster generation times than their hosts but the season is truncated in August by a diapause response to daylengths shorter than I5h. The beginning of the season is delayed until late May by the high thermal requirement to terminate diapause. These local responses to temperature and photoperiod result in different phenologies which, while appropriate locally, are disastrous elsewhere. The failure of North American attempts to establish Vancouver A. rubecula is attributed to the diapause characteristics of the released insects. They entered diapause while ambient temperatures remained warm enough for morphogenesis and were unable to survive the obligatory period to diapause termination. Manipulation of the diapause response is one technique in ecological pest management. A methodology for a breeding program and its analysis is presented. Practical suggestion for biological control efforts are made and the role of individual physiological responses in insect seasonal ecology are discussed. / Land and Food Systems, Faculty of / Graduate

My study was designed to answer two main questions: 1. ) Do the bees, through their foraging behavior, alter the rates of salmonberry nectar productivity? 2. ) Do the plants, through their rates of nectar secretion, alter the foraging behavior of the bees? Since there are well-documented examples of morphological coadaptations between plants and their pollinators, it was reasonable to suppose that physiological/behavioral coadaptations exist as well. Thus I hypothesized that the above questions would be answered in the affirmative. Though the two questions have been individually studied by several biologists, I felt it important to examine the possible reciprocal responses of plants and pollinators as they occur in a natural community context. Nectar productivity of salmonberry flowers (Rubus spectabilis, Pursh) was investigated using flowers isolated for various lengths of time from insect visitors. Nectar volumes were extracted using micropipettes and sugar concentrations were determined with a hand refractometer. Volumes and sugar concentrations were then used to calculate calories/hour. Nectar standing crop (calories/flower) was similarly derived using untagged flowers. During the study I monitored temperature, sunshine levels, relative humidity, date of sampling, time of sampling, and the androecium diameters of all flowers sampled. It was found that an increase in experimental extraction rate brought about a corresponding decrease in productivity. This result is opposite to that reported by other authors, yet it was found that this result was not due to flower damage or to artificial fertilization of flowers. This flower response to simulated visitation frequency may be of competitive advantage to flowers not being used by pollinators present in the area, Productivity and nectar standing crop decreased as the salmonberry flowering season progressed, and decreased throughout the course of each day as relative humidity fell and air temperatures increased. This decline in productivity reflected decreases in volumes of nectar secreted, though sugar concentrations increased with increasing sunshine levels. Younger flowers apparently secreted calories/hour at higher rates than older flowers, this again reflecting trends in volumes of nectar secreted. In each sample of ten flowers, there were four which secreted at rates significantly higher than the remaining six. Further, the four most productive flowers secreted at more predictable rates in trends of the environmental variables monitored during the study. Throughout the season there was a dramatic increase of .bumblebees (Bombus sitkensis, Nylander) observed at patches of salmonberry flowers. Throughout each day, the bees increased in density as sunshine levels and temperatures increased and relative humidity fell. The bees foraged from the more productive younger flowers more frequently than older flowers, and increasingly foraged from older flowers as nectar abundance in all flowers declined through the day and season. In addition, they may also have been avoiding increasing numbers of flowers they approached, though this conclusion must remain tentative. Bumblebee behavior was more predictable during the early morning hours of each day as opposed to hours in the afternoon. It is postulated that, this was because bumblebees experience more uniform energy conditions in the morning. Based on the distribution curves of nectar resources and bee density, it is postulated that plants compete for pollinators early in the day and early in the season, while bees compete for nectar later in the day and later in the season. This hypothesis is further supported by observations on the shifts in bee foraging behaviors. / Science, Faculty of / Zoology, Department of / Graduate