Many organisms, especially animals like insects, which depend on the environment for body heat, have growth stages and life cycles that are highly dependent on temperature. To better understand and model how insect life history events progress, for example in the emergence and initial growth of the biogeographical research subjects, we must first understand he relationship between temperature, heat accumulation, and subsequent development. The measure of the integration of heat over time, usually referred to as degree-days, is a widely used science-based method of forecasting, that quantifies heat accumulation based on measured ambient temperature. Some popular methods for calculation of degreedays are the traditional sinusoidal method and the average method. The average method uses only the average of the daily maximum and minimum temperature, and has the advantage that it is very easy to use. However, this simplest method can underestimate the amount of degree-day accumulation that is occurring in the environment of interest, and thus has a greater potential to reduce the accuracy of forecasting insect pest emergence. The sinusoidal method was popularized by Allen (1976, [1]), and gives a better approximation to the actual accumulation of degree-days. Both of these degree-day accumulators are independent of typical heating and cooling patterns during a typical day cycle. To address possible non-symmetrical effect, it was deemed prudent to construct degree-day accumulators to take into account phenomena like sunrise, sunset, and solar noon. Consideration of these temporal factors eliminated the assumption that heating and cooling in a typical day during the growth season is symmetric. In some tested cases, these newer degree-day integrators are more accurate than the traditional sinusoidal method, and in all tested cases, these integrators are more accurate than the average method. After developing the newer degree-day accumulators, we chose to investigate use of a logistic phenology model similar to one used by Onsager and Kemp (1986, [54]) when studying grasshopper development. One reason for studying this model is that it has parameters that are important when considering pest management tactics, such as the required degree-day accumulations needed for insects in immature stages (instars) to be completed, as well as a parameter related to the variability of the grasshopper population. Onsager and Kemp used a nonlinear regression algorithm to find parameters for the model. I constructed a simplex algorithm and studied the effectiveness when searching for parameters for a multi-stage insect population model. While investigating the simplex algorithm, it was found that initial values of parameters for constructing the simplex played a crucial role in obtaining realistic and biologically meaningful parameters from the nonlinear regression. Also, while analyzing this downhill simplex method for finding parameters, it was found there is the potential for the simplex to get trapped in many local minima, and thus produce extraneous or incorrectly fitted parameter estimates, although Onsager and Kemp did not mention this problem. In tests of my methods of fitting, I used an example of daily weather data from Onefour, AB, with a development threshold of 12 ±C and a biofix day of April 1st, as an example. The method could be applied to larger, more extensive datasets that include grasshopper population data on numbers per stage, by date, linked to degree accumulations based on the non-symmetrical method, to determine whether it would offer significant improvement in forecasting accuracy of spring insect pest events, over the long term. / xii, 106 leaves ; 29 cm

A major challenge in ecology is to understand intraspecific variation in life histories. Variation in resource availability can lead to differences in reproductive allocation and life histories. Grasshoppers are a good organism for the study of variation in life histories, since they exhibit life history plasticity in response to biotic and environmental factors. An optimality model for grasshoppers was developed that predicts optimal total allocation to reproduction and optimal effort-per-offspring as functions of resource availability and mortality. Relative allocation to reproduction is predicted to increase with resource availability, while relative allocation to survival declines. A resource-based trade-off between egg size and number does not exist, as optimal egg size is predicted to be independent of resource intake. I examined if changes in reproductive allocation and survival of Melanoplus sanguinipes (Fabricus) under a range of resource availabilities fit the predictions of the model. The patterns of reproductive allocation and survival in the field were in qualitative agreement with the predictions. I examined the importance of density, resources, and parasitism on the life history patterns of grasshoppers. I conducted an experiment to examine if differences in reproductive allocation of M. sanguinipes are primarily explained by exploitative competition. Per capita resource availability explained a significant amount of the variation in reproduction , as expected with exploitative competition. M. sanguinpes grasshoppers appeared to trade off resource allocation to reproduction for that of allocation to survival, because per capita resource availability did not affect survival. Careful examinations of changes in life history characteristics in response to parasitism are lacking, despite the fact that parasites often influence resource availability for the host. I investigated the effects of a grasshopper ectoparasitic mite on grasshopper reproduction and survival. Mites had small effects on grasshopper survival. As predicted, both species had reduced initial and total reproduction, and completed development of a lower percentage of ovarioles initiated when parasitized. These experiments act to expand our knowledge of life history theory and further our understanding of grasshopper life history variation and population fluctuations.

Recent theoretical developments have led to a renewed interest in the potential role of chromosomal rearrangements in speciation. Australian morabine grasshoppers (genus Vandiemenella, viatica species group) provide an excellent study system to test this potential role, because they show extensive chromosomal variation: 12 chromosomal races/species with parapatric distributions. The research in this thesis involves the application of molecular genetic analyses to examine patterns of gene introgression among chromosomal races of Vandiemenella at three different spatial scales: local-scale hybrid zone analysis, island-scale phylogeography, and continental-scale phylogeography. The aims of these multi-scale analyses are to investigate whether chromosomal races represent genetically distinct taxa with limited gene flow, and to infer the historical biogeography of Vandiemenella and evolutionary origins of their parapatric distributions. Karyotype and 11 nuclear markers revealed a remarkably narrow hybrid zone with substantial linkage disequilibrium and strong deficits of heterozygotes between the chromosome races P24(XY) and viatica17 on Kangaroo Island, suggesting that the zone is maintained by a balance between dispersal and selection against hybrids (tension zone). Selection that maintains the stable hybrid zone is unlikely to be operating only on loci linked to rearranged chromosomes. Island-scale and continental-scale phylogeography using multiple nuclear markers indicated that Vandiemenella chromosome races/species generally represent genetically distinct taxa with reduced gene flow between them. In contrast, analyses of a mitochondrial gene showed the presence of distinctive and geographically localised phylogroups that do not correspond with the distribution of the Vandiemenella taxa. These discordant population genetic patterns are likely to result from introgressive hybridization between the taxa and range expansions and contractions. Overall, our molecular analyses favour the allopatric mode of diversification for the evolution of Vandiemenella and do not support the stasipatric speciation model of White (1978). Patterns of genetic differentiation between the chromosomal races analysed at three different spatial scales show dynamic responses of the grasshoppers to past climatic fluctuations, leading to opportunities for long-term isolation and allopatric fixation of new chromosome variants and molecular mutations at many loci. Further analyses are necessary to assess potential roles of chromosomal rearrangements in facilitating diversification in Vandiemenella by reducing recombination within the rearranged chromosome segments.

Scientific literature indicates potential for using plant extracts to control arthropod pests thereby decreasing the amount of synthetic chemicals introduced into the ecosystem. The research presented below tested several control candidates in a field settig to determine if selected oils can be used to control grasshopper infestations. Two field studies tested the effects of five plant extract oils on grasshopper pests in southern Alberta: Rosmarinus officinalis, Cedrus deodorata, Melaleuca alternifolia, Eucalyptus globulus, and Azadirachta indica. Grasshopper abundance increased in the first study in all plots and decreased in the second study in all plots. A third study was conducted in a greenhouse where grasshoppers were treated with two concentrations of cedarwood and rosemary oil and were monitored for eight days for mortality and behavioural effects. A non-target study was conducted in order to determine if control candidates would negatively affect other beneficial arthropods. Cedarwood, neem oil and carbaryl bait were tested on the mortality of Carabidae and Phalangiidae using pitfall trap sampling. / viii, 98 leaves : ill., maps ; 29 cm.

Submitted by Caroline Falcao (caroline.rfalcao@ufpe.br) on 2017-04-10T16:55:55Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-TyagoEufrásioSouza.pdf: 1735075 bytes, checksum: 71d298cc88578885aa679bda01ec12e1 (MD5) / Made available in DSpace on 2017-04-10T16:55:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-TyagoEufrásioSouza.pdf: 1735075 bytes, checksum: 71d298cc88578885aa679bda01ec12e1 (MD5) Previous issue date: 2012-02-29 / As espécies de gafanhotos Ommexecha virens(Ommexechidae),Xyleus discoideus angulatus,Tropidacris collaris(Romaleidae) eSchistocerca pallens(Acrididae)ocorrem na região do Nordeste do Brasil. Apresentam seus cariótipos simétricos com número cromossômico, 2n=23 (X0, machos) e 2n=24 (XX, fêmeas), porém T. collaris, S.pallense X.d.angulatus apresentam os cromossomos com morfologia acrocêntrica, enquanto que O. virens apresenta o par cromossômico G1submetacêntrico. Variaçõesrítmicasnocomportamentoapresentadaspordiversosorganismossão pertencentes ao ciclo circadiano.Com o uso da técnica de Hibridização in situ Permanente (PISH), foi mapeada a posição do gene de cópia única Per, um dos genes do relógio circadiano,em cromossomos meióticos das espécies O. virens,X.d.angulatus,T. collariseS.pallens.Os cromossomos meióticos destas espécies foram obtidos através da técnica clássica de esmagamento de folículos testiculares. As sondas utilizadas foram obtidas de plasmídeos carregando fragmentos do gene Per originários do genoma do drosofilídioZaprionus indianus. Após a hibridizaçãoin situ, o material foi fotografado usando contraste de fase. Nasquatroespéciesde gafanhotos citadas anteriormente, o gene Perfoi mapeado no maior par autossômico, G1.Analisados conjuntamente os resultados de mapeamento do genePer nestasespéciescom a localização de outros genes de cópia única e de cópia repetitiva, observa-se uma localização preferencial dos genes decópia única nos pares autossômicos grandes e, genes de cópia repetitiva, nos pares médios e pequenos. Estesresultadostambémapontam paraumaconservação molecular deste gene nos Orthoptera, como observado em Dípterae Lepdoptera; possívelmente a conservaçãona localização cromossômicasejaum reflexodaconservaçãomolecular.Localizações cromossômicas dediversosgenes constitutivos em representantes das famílias Ommexechidae, Romaleidae e Acrididaesão informações relevantes para o entendimento das relações evolutivas entre estesgafanhotos, além disso,fornecemmarcadores para o sequenciamento do genoma destas espécies. / The species of grasshoppers Ommexecha virens(Ommexechidae) Xyleus discoideus angulatus, Tropidacris collaris(Romaleidae) and Schistocerca pallens(Acrididae) occur in the Northeast region of Brazil. Present theirsymmetricalkaryotypeswithchromosome numbers, 2n = 23 (X0, males) and 2n = 24 (XX, females), butT. collaris, S. pallensand X. d. angulatuspresent the acrocentric chromosome morphology, while O. virensshows the submetacentric L1chromosome pair.Rhythmic variationsin behaviorpresented byvarious organimsare belongingto the circadian cycle.Using the technique of Permanent insituhybridization (PISH), has mapped the position of thesingle-copy genePer, one of the clock genes, in meiotic chromosomes of the species O. virens, T. collaris, S. pallensand X. d. angulatus. The meiotic chromosomes of these species were obtained by the classical technique of crushing testicular follicles. The probe used was obtained from plasmids carrying the gene Perfragments originating from the genome of drosofilid Zaprionusindianus. After in situ hybridization, the material was photographed using phase contrast. In thegrasshoppersspecies mentioned above, the Pergene was mapped in largest autosomal pair, L1. Taken together the results of Pergene mapping in these species with the location of other single-copy genes and repetitive copy, there is a preferential localization of single copy genes in large autosomal pairs and copy repetitive genes, the couplepairsand small. These results also point to a molecular conservation of this gene in the Orthoptera, as observed in Diptera and Lepdoptera, possible conservation in chromosomal location is a reflection of molecular conservation. Chromosomal locations of severalconstituentgenes in representatives of the families constituting Ommexechidae, RomaleidaeandAcrididae are relevant information for understanding the evolutionary relationships in the locusts, and provides markers for mapping the genome of these species.

Doctor of Philosophy / Department of Biology / Anthony Joern / Aboveground and belowground food webs are linked by plants, but their reciprocal influences are seldom studied. Because phosphorus (P) is the primary nutrient associated with arbuscular mycorrhizal (AM) symbiosis, and evidence suggests it may be more limiting than nitrogen (N) for some insect herbivores, assessing carbon (C):N:P stoichiometry will enhance my ability to discern trophic interactions. The objective of this research was to investigate functional linkages between aboveground and belowground invertebrate populations and communities and to identify potential mechanisms regulating these interactions using a C:N:P stoichiometric framework. Specifically, I examine (1) long-term grasshopper community responses to three large-scale drivers of grassland ecosystem dynamics, (2) food selection by the mixed-feeding grasshopper Melanoplus bivittatus, (3) the mechanisms for nutrient regulation by M. bivittatus, (4) food selection by fungivorous Collembola, and (5) the effects of C:N:P on invertebrate community composition and aboveground-belowground food web linkages. In my analysis of grasshopper community responses to fire, bison grazing, and weather over 25 years, I found that all three drivers affected grasshopper community dynamics, most likely acting indirectly through effects on plant community structure, composition and nutritional quality. In a field study, the diet of M. bivittatus was dominated by forbs with grasses constituting only a minor fraction of their diet under ambient soil conditions, but grass consumption approximately doubled as a result of changes in grass C:N:P. M. bivittatus was found to rely primarily on selective consumption of foods with varying nutritional quality, rather than compensatory feeding or altering post-ingestive processes, to maintain C:N homeostasis in a laboratory experiment. In a soil-based mesocosm study, I show that Collembola feed on both saprophytic and AM fungi, in some cases exhibiting a slight preference for AM fungi. In the final study, although I did not find the expected indirect relationship between soil Collembola and aboveground herbivory as mediated through host plant quality, there were significant effects of root C:N and AM colonization on Collembola density and of plant C:N on aboveground herbivory. Overall, this research shows that host plant C:N:P stoichiometry can influence both above- and belowground invertebrate population, community, and food web dynamics.

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published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Hybrid zones are regions where genetically differentiated forms come together and exchange genes through hybrid offspring. The study of characters gradually changing across such zones (clines) can give insight into evolutionary processes, providing exceptionally sensitive estimates of the intensity of selection, and allowing the detection of loci that might be involved in reproductive isolation and speciation. The Alpine grasshopper Podisma pedestris has a hybrid zone in Southern France where two populations meet. They differ in their sex chromosome system, and strong selection against hybrids is observed. These distinct populations likely have split and re-joined several times during the Quaternary glacial cycles. A model explaining the selection observed against hybrids postulates hundreds of loci of small effect spread over two differentiated genomes meeting in secondary contact. Yet, over 50 years of study to-date non have been discovered. However, so far the study of P. pedestris has not made use of high-throughput sequencing data which provides an unprecedented resolution of molecular markers. I am aiming to close the gap with this thesis. I assemble the grasshopper's mitochondrial genome sequence and infer what proportion of its genome is made up by mitochondrial inserts (Numts). Using transcriptome data from two individuals, I then go on to fit demographic models, finding the populations split approximately 400 000 years ago and that the current-day population sizes are considerably smaller than the ancestral one. The final data chapter explores the genetic architecture of the hybrid zone using data from a targeted sequence capture of hundreds of loci covering some 10 000 polymorphic sites. Only two loci under selection are identified, which is surprising given the power of the analysis. Both loci are located on the X chromosome and are subject to weak selection (0.3% and 0.03%). This shows the power of hybrid zone analysis to infer targets of selection. The results are discussed in light of a theoretical chapter on the 'inexorable spread' phenomenon and lead to the proposal for further research into the causes of the reproductive isolation observed between the grasshopper populations.