Doctor of Philosophy / Department of Entomology / Franklin Arthur / James R. Nechols / The Indianmeal moth, Plodia interpunctella Hubner, is capable of infesting a number of different commodities including a wide variety of grains, nuts and finished stored products. Therefore, control of the Indianmeal moth is especially needed in areas where food is being stored for human consumption. Increased concerns of consumers and producers regarding the impact of conventional insecticides on the environment and on human health has prompted scientists and the agricultural chemical industry to search for insecticides that do not affect mammalian nervous systems and have limited effects on non-target organisms. One group of insecticides with reduced risks is insect growth regulators (IGRs), which are substances that mimic insect hormones essential to normal development and reproduction. Currently methoprene, a juvenile hormone analog, is labeled for direct application to stored grains, as well as a contact insecticide and as an aerosol application inside mills, warehouses, and indoor food storage facilities. Surface treatments and aerosol space applications can be effective ways to treat the interior surfaces and storage areas of warehouses and food processing facilities. There is little recent research with large-scale aerosol applications in storage sites; furthermore, there are no published references in the scientific literature regarding efficacy of using methoprene alone in aerosol form. Therefore, the purpose of this research was to evaluate the use of surface and aerosol applications of methoprene on finished stored-product packaging materials and facilities for the control of P. interpunctella. Results of this research showed that while methoprene has good residual activity, and efficacy is unaffected by temperature, surface applications of methoprene on packaging materials is not as effective for control of P. interpunctella as aerosol applications of methoprene. Aerosol methoprene is highly effective alone and in combination with conventional chemicals for control of eggs and wandering-phase larvae. Simulations with a population growth model make it possible to estimate impact of insecticide treatments at different temperatures and application times on populations of P. interpunctella. Aerosol treatments are also economically viable as part of an overall integrated pest management program.

Doctor of Philosophy / Department of Entomology / Larry L. Buschman / Kun Yan Zhu / Genomic information for lepidopteran insects, particularly agricultural pest species, is very limited but urgently needed due to their economic importance and biodiversity. The huge economic losses ($ 1-2 billons / year) caused by the European corn borer (Ostrinia nubilalis, Hübner, ECB) makes this insect species one of the major pests of corn in the United States and western world. Management of ECB by conventional methods is limited but has had a great success by transgenic Bt (Bacillus thuringiensis) corn, which targets insect gut. However, the widespread use of Bt corn may lead to the development of Bt resistance in ECB. Knowledge of genes expressed in the insect gut is considered crucial for understanding basic physiology of food digestion, their interactions with Bt toxins and pathogens, and for discovering new targets for pest management. A large database of 15,000 expressed sequence tags (ESTs) was established from the ECB larval gut. To our knowledge, this database represents the largest gut-specific EST database from a lepidopteran pest. Analysis of 10 aminopeptidase-like genes between Cry1Ab–resistant and –susceptible ECB larvae revealed that aminopeptidase P-like (OnAPP) gene is a strong candidate for its role in Bt toxicity and resistance. The RNA interference mediated reduction in the transcript level of OnAPP gene in ECB larvae resulted in their reduced susceptibily to Cry1Ab. Analysis of the chitinase-like gene (OnCht) revealed its essential role in regulating chitin content of peritrophic membrane (PM). Our results suggest that OnCht may influence food digestion, nutrient absorption or movement of digestive enzymes through the PM and can be an important target for insect management. We also identified and characterized six genes involved in the innate immune defense response in ECB and showed that the expression of these genes were induced when challenged with bacteria. In addition to these results, this research generated significant genomic information for the development of microarray from the larval gut of ECB. The establishment of the feeding-based RNA interference technique could potentially help in delivering dsRNA orally to ECB for high throughput screening of effective genes to be targeted for insect pest management.

The nutritional and chemical properties of three Chinese pollens, sorghum (Sorghum sp.), rapeseed (Brassica napus) and sunflower (Helianthus annuus), were studied. All three pollens were highly preferred, with sunflower pollen the highest, by young honey bees (Apis mellifera). Rapeseed pollen increased honey bee's longevity the greatest; however, sorghum and sunflower pollens also increased the longevity relative to the no-pollen group. All three pollens had high energy (about 5 kcal/g) and carbohydrate quantities (58%). The protein, fat, and fiber levels were 27%, 7%, and 9% in rapeseed pollen, 26%, 5%, and 13% in sorghum pollen, and 15%, 5%, and 10% in sunflower pollen. alpha-Tocopherol was high in sunflower pollen (61 μg/g), lower in rapeseed (33 μg/g) and sorghum pollen (15 μg/g). K, Ca, Mg, Fe, Cu, and Mn were high in all three pollens. These data suggest that a pollen which is highly preferred by honey bees is not necessarily the most nutritious.

The purpose of this thesis is to examine the role that myo-inositol plays in feeding and oviposition by the tobacco hornworm, Manduca sexta. The results show that; (1) of all of the compounds tested only myo-inositol and epi-inositol consistently elicited a rapid, phasic-tonic firing response from taste receptors, (2) inositol is a feeding stimulant for both fifth and third stage M. sexta larvae, (3) M. sexta larvae do not need dietary inositol for normal growth and development, but females need dietary inositol as larvae for egg production as adults, (4) inositol is also a utilizable carbohydrate for M. sexta larvae and considering its relative abundance in Solanaceous plants, it may serve as an important carbohydrate source, (5) inositol does not appear to be important in oviposition, (6) inositol is correlated to protein levels in young tomato and tobacco plants.

The goal of this dissertation was to investigate some of the factors that determine species diversity across trophic levels at both broad and local scales. The taxa used to address these questions were grass and forb dwelling arthropods, mainly insects, found at experimental sites. The overriding question guiding this research is; what are the processes that determine arthropod diversity at local and regional scales? At local scales, I investigated trophic level diversity using correlational studies, measuring the natural variation in two grassland ecosystems. Results from this study support hypotheses from other empirical studies demonstrating that changes in diversity of a single trophic level can cascade to effect diversity at other, nonadjacent trophic levels. These studies were supplemented with a long-term manipulative experiment using the same ecosystems, in which I manipulated plant resources and higher trophic levels. After three years, and one year after the last experimental manipulations were applied, the plant resources manipulation (addition of fertilizers) tripled the average number of herbivore individuals and decreased herbivore diversity. Also at the local scale of diversity interactions, I conducted additional experiments measuring trophic level diversity, using the forage crop alfalfa (Medicago sativa ) and the associated arthropods as a model system. In this study I again manipulated plant resources and higher trophic levels and found significant positive associations between plant resources, plant defense, and herbivore diversity. Additionally, predator diversity and abundance were consistently associated with higher levels of herbivore diversity. This corroborates previous studies in these agricultural ecosystems demonstrating complex indirect trophic level interactions To examine larger scale patterns of diversity, I investigated regional and latitudinal gradients in arthropod abundance and diversity. Regionally, I conducted a study using alfalfa agroecosystems again and investigated the effects of climatic variation on the diversity of arthropod trophic groups across a large geographical area, from Colorado to Southern Arizona. I found that parasitoids were most susceptible to variations in climate, while herbivores and other enemies were more resilient to local climate, also in agreement with other studies demonstrating the differential susceptibility of natural enemies to climatic variation Finally, I investigated arthropod diversity along a latitudinal gradient from northern Colorado (N 40°30') to Ecuador (S 0°42'), using identical methods along the gradient and controlling some aspects of the type of community sampled (open fields versus forest edges). Arthropod species richness increased from the temperate latitudes to tropical regions, this however was not reflected in arthropod family richness or abundance. In addition, I found that controlling for community type across latitudinal gradients explained little of the variation in arthropod diversity. These results suggest that abiotic diversity-promoting mechanisms have a stronger influence on arthropod diversity than do biotic differences between community types. Results from the combined research that comprised my dissertation are the most thorough demonstration of 'diversity cascades' (indirect effects of biotic interactions on biodiversity) demonstrated to date. This is relevant to understanding a major global challenge: loss of biodiversity. Similarly, the consistent effect of plant resources on plant and animal abundance and diversity is relevant to the ubiquitous anthropogenic input of elements such as nitrogen and phosphorus. The results here are consistent with the hypothesis that as overall diversity increases, natural enemies have stronger effects on biotic communities, while less diverse communities are dominated by the effects of plant resource. (Abstract shortened by UMI.) / acase@tulane.edu

Empirical studies in Ecology have shown that insect herbivores feeding on plants with high concentrations of secondary metabolites are more likely to be successfully parasitized. This dissertation research examined one potential mechanism by which plant secondary metabolites render herbivores vulnerable to attack by natural enemies: secondary metabolites may have a negative effect on the physiology and immune response of lepidopteran larvae (caterpillars). An experimental approach tested the novel hypothesis that herbivores feeding on plants with high concentrations of iridoid glycosides and amides/imides are more likely to be successfully parasitized because of a weakened immune response In controlled experiments when the specialist nymphalid caterpillar, Junonia coenia, sequestered high levels of iridoid glycosides it was immunocompromised compared to caterpillars sequestering at low concentrations. The immune response of the generalist arctiid caterpillar, Grammia incorrupta, was not affected by feeding on diets with high concentrations of iridoid glycosides. The effects of imides/amides on caterpillar immune responses were also tested using specialist geometrid caterpillars, Eois spp., and the generalist noctuid caterpillar, Spodoptera exigua. There was no significant effect of the imides/amides on the immune response of any of these caterpillars. Lastly, the immune response was measured across 15 species of caterpillars from 10 different families. Caterpillars with a strong immune response were less likely to be parasitized. When compared to other defenses against parasitoids, the defensive value of the immune response against parasitoids is at least an order of magnitude greater than behavioral or morphological defenses Together, these results show that both plant chemistry and natural enemies play an influential part in determining diet breadth of caterpillars. Many ecological studies have shown that caterpillars that specialize on specific host plants and evolve to sequester the host plant secondary metabolites are protected from predators due to their acquired toxicity. However, the data from this dissertation research show that this is not always the case, and that caterpillars sequestering in high concentrations are immunocompromised and may be susceptible to greater parasitism. The current paradigm of how plant-caterpillar-predator interactions are structured should take into account more specialized interactions like those shown in this dissertation / acase@tulane.edu

We know little about how English to Speakers of Other Languages (ESOL) preservice teachers' prior experiences and beliefs shape their learning process in teacher preparation programs, particularly in the area of second language (L2) reading instruction although research on preservice teachers' antecedents has offered insights into our understanding of how they learn to become teachers (Johnson, 1992, 1994; Wilson, Floden, & Ferrini-Mundy, 2001). This inquiry was designed to contribute to such knowledge. / The participants were nine ESOL pre-service teachers enrolled in an ESOL program of a large urban university in the southeastern region of the United States. Using modified versions of Language Teaching/Learning Beliefs Questionnaire (Brown & Rogers, 2002), of Multidimensional TESL Theoretical Orientation Profile (Johnson, 1992) and of the Theoretical Orientation of Reading Profile (Deford, 1985), reflective essays submitted during admission, observations, interviews, videotapings, and focus group, the study explored answers to questions regarding the influence of ESOL preservice teachers' antecedents on their learning in coursework and field experiences over three semesters. The inquiry stemmed from the framework of constructivism (Crotty, 1998), of introspection and retrospection (Scarino, 2005), and of How People Learn (Donovan & Bransford, 2005). Data were analyzed using grounded theory and constant comparative techniques (Glaser & Strauss, 1967; Lincoln & Guba, 1985). / Findings indicated that faculty used various strategies to address teacher candidates' background for conceptual change and development of professional dispositions. Programmatic decisions to select teacher candidates with specific background in learning an L2 were beneficial but teacher preparation programs may need additional instruments to tap candidates' entering beliefs more effectively. Although some aspects of the participants' prior experiences were not beneficial, these experiences generally contributed to their understanding of ESOL education, visions of L2 instruction, and the development of professional dispositions as related to culturally responsive and socially just teaching in important ways. Also, participants' views of reading, visions of reading instruction, reading instruction in field experiences, and their understanding of literacy theory and pedagogy were primarily influenced by their first language reading experiences. Finally, participants were less confident in articulating a vision of L2 reading instruction because of limited L2 reading prior experiences.

This study combined an intensive site-specific inventory of the spider family Salticidae with an extensive taxonomic review of a subset of the family throughout the Neotropics. This collection of over 8,000 adult salticids from lowland rainforest in Costa Rica's La Selva Biological Station yielded 103 species from 50 genera. At least one genus and ten to fifty percent of these species are new to science. Natural history and range information is presented for the sixteen most abundant species in understory and canopy fogging samples. Species richness estimators predict that quantitative understory sampling captured 88% to 98% of the species accessible to our methods during the survey period. We use this unusually comprehensive empirical dataset to evaluate performance of six parametric and seven nonparametric species richness estimators. Among parametric curve-fitting models, Soberon and Llorente's log model provides the best fit, least bias, and most accurate results at most sample sizes. Of nonparametric estimators, Chao1 and Chao2 most quickly reduce the negative bias all show at small sample sizes. Stratifying sampling by method, habitat, and site improved richness estimation by enabling us to diagnose edges of our target community and its partitions by identifying "leakage" of rare species from other partitions in which these species were common. Stratified sampling also revealed differences in subfamily-level faunal composition across partitions and exposed hints of elaborate niche partitioning among taxa, particularly within the speciose genus Corythalia. This taxonomic revision of the Neotropical genera Cobanus F. O. Pickard-Cambridge 1901 and Sidusa, Peckham and Peckham 1896 shows them to be closely related to one another and almost doubles the size of each. Twenty-four species are newly described here, twelve re-described, three synonymized, two transferred to other genera, and several recognized as being misplaced. This paper provides character matrices for specimen identification and summarizes known distribution and natural history information for all species of Cobanus and Sidusa. Phylogenetic analysis of morphological characters in these species and members of thirty other euophryine genera supports the sister relationship and mutual monophyly of Cobanus and Sidusa, and provides insight into character variation and higher-level relationships within the subfamily Euophryinae.

This dissertation reports on a study conducted to examine the morphological, behavioral, and environmental sources of variation in the structure of house cricket, Acheta domesticus, calling song. Song variations may be important in female mating decisions and influence male mating success. Eleven song parameters were measured: chirp duration, interchirp duration, syllable number, syllable duration, intersyllable duration, mean frequency, frequency intensity, minimum frequency, maximum frequency, syllable intensity, and intensity difference between syllable and frequency intensity. Morphological factors examined included body: mass, length, color, asymmetry, intactness; and male age. Behavioral factors were timing of song bouts and proclivity to sing. Environmental conditions of high population densities were simulated by temporarily placing males into an arena with three other males. The calling song structure of tactilely isolated males resulted in three factors: frequency (mean, minimum, and maximum frequencies); intensity (syllable intensity, and intensity difference); and variability (difference between syllable intensity and frequency intensity). Males with high body intactness sang at lower frequencies. Asymmetrical males sang more intense songs. Large males sang with more intensity and frequency variability. Intermale competitions resulted in distinguishable linear dominance hierarchies. Lower-ranking males sang less often than higher-ranking males, altered singing times, and sang quieter songs. Intermale competition resulted in males altering song structure. Analysis of post-competitive songs resulted in three factors: frequency (mean and maximum frequencies, and intensity difference); energy (duty-cycle, intensity, and minimum frequency) and variability (unchanged). Higher-ranking asymmetrical males sang at lower frequencies. Higher-ranking males sang with greater energy, and timed their singing to female receptive times. Higher-ranking, large, intact males sang with less variability. This study indicated that A. domesticus males signal phenotypic information via their calling song characteristics. More specifically, in low population densities males signal information concerning their fitness-related qualities. After having established dominance orders, the male signal information concerning their rank in conjunction with fitness. The implications of this study were that intermale competition altered the song cues available to the females and may alter female mating decisions.

Pandora moth (Coloradia pandora Blake) is a phytophagous insect, defoliating ponderosa pine trees in the western United States. However, long-term studies of this insect and its effects on the forest ecosystem have not been conducted. Using dendrochronological techniques, I examined past timing and intensity of defoliation through its effects on radial growth of trees in the forests of south central Oregon. Pandora moth leaves a distinctive ring-width "signature" that was easily identifiable in the wood. The growth for the first year of the signature was half the normal ring-width with narrow latewood. The following two years produced extremely narrow rings, with the entire suppression lasting from 4 to 18 years. Twenty-two individual outbreaks were reconstructed from this 620 year chronology. I found that pandora moth outbreaks were episodic on individual sites, with a return interval of 9 to 156 years. Conversely, on the regional scale of south central Oregon, outbreaks demonstrated a 37-year periodicity. On average, pandora moth defoliation caused a 29% mean periodic growth reduction in defoliated ponderosa pine trees. Spread maps of the first year that sites demonstrated suppression were plotted revealing an apparent annual spread of the outbreaks. Examination of a fire history on one pandora moth outbreak site suggested that pandora moth outbreaks delay fire by interrupting the needle fall needed for fire spread. Superposed epoch analysis showed that the year that the outbreak was first recorded was significantly dry and the fourth year prior was significantly wet. Therefore, climate may be a triggering factor in pandora moth outbreaks. The stem analysis demonstrated that the percent volume reduction was greatest at the base of the tree and declined further up the bole. The percent volume reduction in the canopy of the trees was variable with outlying high and low values. The mean volume reduction per outbreak was .053 m³ per tree. Although this insect is considered a forest pest and causes inconvenience for people living nearby, pandora moth is not as widespread and damaging as some other phytophagous insects. However, its very distinctive ring-width signature and the length of the ponderosa pine record enables reconstruction of very long outbreak histories, which may deepen our understanding of the interaction between defoliating insects and their ecosystem.