Grasshoppers are able to spontaneously drop, or autotomize, their large metathoracic legs, at the joint between the second and third leg segments. Previous work demonstrated that in the grasshopper, Barytettix psolus, autotomy transneuronally induces atrophy in a group of six metathoracic muscles on the ipsilateral side. These muscles are neither damaged nor denervated by the loss of the leg. The experiments presented in this dissertation support and extend the earlier work by including twelve additional metathoracic muscles, one of which was discovered as a result of these studies. These experiments demonstrated that atrophy varied both between muscles, as well as between fibers within individual muscles. Some muscles degenerated uniformly, whereas others contained persisting fibers long after neighboring fibers degenerated. Extent of atrophy in each muscle was quantified by measurement of total protein content. Histochemical staining of myofibrillar ATPase activity in a subset of muscles indicated that slow type fibers comprised the majority of those persisting following autotomy. Immunohistochemical experiments suggested that persistance of muscle fibers was correlated with innervation both by motor neurons (MNs) containing proctolin-like immunoreactivity (PLI), and by an inhibitory MN containing gamma-aminobutyric acid (GABA)-like immunoreactivity (GLI). The distributions of PLI and GLI indicated that these two types of MNs innervate muscles in parallel. In an attempt to identify the proctolin-like substance, muscle extracts of fourteen muscles were purified by HPLC and subjected to bioassay for proctolin-like bioactivity (PLB). Nine muscles with PLI also contained PLB. These experiments support the presence of proctolin in muscles with PLI. Four out of the five muscles lacking PLI also contained PLB. It is likely that these muscles contain at least one bioactive peptide that is biochemically similar to proctolin. These experiments are the first to suggest the association of proctolin-like substances with the majority of leg muscles in any insect. My immunohistochemical data combined with the results of previous experiments on the functions of proctolinergic and GABAergic innervation suggest that proctolin or proctolin-like substances are commonly used to maintain postural tonus in metathoracic leg muscles during standing and locomotory activities.

The follicle cell-specific (FCS) gene, a 3,023 bp gene specific to follicle cells of the mosquito, Aedes aegypti, was characterized at the nucleotide level. Genomic Southern blots demonstrated that there was only one copy of this gene in the A. aegypti genome. An ovary-specific cDNA library was constructed from female mosquitoes 24 hours post blood meal. Then a cDNA clone containing the complete coding region was identified, and its nucleotide sequence was determined. The deduced protein contained unusually high levels of alanine and proline. Search of a protein data base revealed that the FCS gene was similar to Drosophila vitelline membrane protein genes, with 47.5% similarity in nucleotide sequence and 46.7% similarity in amino acid sequence. The conserved hydrophobic regions from several vitelline membrane proteins were compared. Another cDNA clone, 1D, was isolated from the cDNA library screened with the FCS gene. These two mosquito genes shared a 60% similarity at the nucleic acid level and a 79.8% similarity at the amino acid level.

Antisera against leucokinin IV were used to test for the presence of leucokinin-like peptides in the central nervous systems of Nauphoeta cinerea, Acheta domesticus, Schistocerca americana, Aedes aegypti, Manduca sexta and Apis mellifera. Leucokinin immunoreactive neurosecretory cells were found in the pars intercerebralis and pars lateralis of the brains of N. cinerea, A. domesticus, A. aegypti, but not in the brains of S. americana, M. sexta and A. mellifera. The neurohemal release sites were also very different among species. In contrast, the distribution patterns of leucokinin immunoreactive neurosecretory cells were very similar among abdominal ganglia of all six species. The identity of the leucokinin immunoreactive material in the brain, corpora cardiaca and abdominal ganglia of N. cinerea was shown by HPLC combined with ELISA. In N. cinerea and A. domesticus, leucokinin and vasopressin were found to co-localize in the same neurosecretory cells. In M. sexta, leucokinin and diuretic hormone co-localized in the same neurosecretory cells in abdominal ganglia, but not in the brain.

In Diptera, small-field retinotopic neurons supply achromatic motion sensitive neurons in the lobula plate, a region thought to control stabilization of yaw, pitch, and roll during flight. If different body shapes, and the flight performance associated with them, place specific demands on the design of control pathways, it might be expected that flies with long bodies and high aerodynamic pitch stability would show specific differences in the organization of such magnocellular achromatic networks. Striking differences emerge in the comparison of 9 species. Tipulids and culicids possess small non-stratified lobula plates, containing only 2-3 large diameter neurons. In syrphids, all VS cells have wide diameters and overlapping fields covering 2-3 times more of the mosaic than those of calliphorids. In asilids (robber flies) vertical cells cannot be identified. Despite these differences, we observe a conserved relationship between terminals of lamina afferents with neurons in the medulla.

Whitebark pine (Pinus albicaulis Engelm.) tree-ring chronologies of 700 to greater than 1,000 years in length were developed for four sites in the Sawtooth-Salmon River region, central Idaho. These ring-width chronologies are used to (1) assess the dendrochronological characteristics of this species, (2) detect annual mortality dates of whitebark pine attributed to a widespread mountain pine beetle (Dendroctonus ponderosae Hopk.) epidemic during the 1909 to 1940 period, and (3) establish the response of whitebark pine tree ring-width growth to climate variables. Crossdating of whitebark pine tree-ring width patterns was verified. Ring-width indices had low mean sensitivity (0.123-0.174) typical of high elevation conifers in western North America, and variable first order autocorrelation (0.206-0.551). Mortality of dominant whitebark pine caused by mountain pine beetle had a maxima at 1930 on all four sites. Response functions and correlation analyses with state divisional weather records indicate that above average radial growth is positively correlated with winter and spring precipitation and inversely correlated with April temperature. These correlations appear to be a response to seasonal snowpack. Whitebark pine is a promising species for dendroclimatic studies.

This study was conducted to determine behavior patterns of the jumping spider Habronattus oregonensis. Time budgets show spiders spend their time out and about, eating, interacting with other spiders, and in hidden behaviors with out and about behaviors dominating. Agonistic encounters occur in the field and were staged in the laboratory. Whether a spider keeps control of the area is determined differently for males than females. In male-male interactions, the size of the spider as measured by weight is important in winning a skirmish regardless of familiarity with an area (residency). For female-female agonistic interactions, however, residency does affect the outcome. In interactions between male-female pairs, the male readily courts the female. Mature virgin females readily accept a mate; other females do not. Finally, experiences from university research were used to develop lesson plans for student study at the secondary level in biology classrooms.

Tree-ring records were used to reconstruct the spatial and temporal patterns of western spruce budworm (Choristoneura occidentalis Freeman) outbreaks in the Rio Grande National Forest (RGNF) of southern Colorado. Reconstructions at 11 host stands showed a synchronous pattern of outbreaks with a peak in the number of trees recording outbreaks over the entire RGNF on average every 24 years. These synchronous periods of outbreaks coincided with periods of increased moisture as indicated by an independently reconstructed summer Palmer Drought Severity Index, while relatively few trees recorded outbreaks during dry periods. The reconstruction on the RGNF does not support the hypothesis that human land use has significantly altered outbreak patterns. Tree response to outbreaks in the RGNF was different from prior studies as reductions in growth were typically detectable only when growth was compared to that of nonhost tree species.

A comparative study was performed to investigate the tolerance levels of beet armyworm to three insecticides, cyfluthrin, profenofos, and methomyl. The field strains were collected from Yuma and Marana, AZ whereas the susceptible laboratory strain was obtained from California. Dosage-mortality data were obtained by topical application on third instar larvae. Compared to the susceptible strain, both Yuma and Marana strains exhibited an increase in the LD50 to cyfluthrin by 15.65 and 5.45-fold, respectively. Both strains also exhibited an increase in the LD50 to profenofos and methomyl by 14.10, 17.77 and 2.95, 8.07-fold, respectively. The cyfluthrin-selected strain (Marana strain) tested for cross resistance to profenofos and methomyl and exhibited an increase in LD50 by 24.68 and 3.32-fold,respectively.

Since its introduction to the U.S., the South American fire ant Solenopsis invicta has displaced its native congener S. geminata from many habitats. Repeated censusing indicates that the distribution of these ants in the northern Apalachicola National Forest is stable, with S. invicta monopolizing pond margins, both species occupying roadsides, and S. geminata found alone in the woods. A series of investigations revealed a number of differences between S. invicta and S. geminata that may play a role in determining the distribution of the two species. Attributes of S. invicta which have likely contributed to its displacement of S. geminata include: larger colony size, quicker colony growth facilitated by brood raiding, reproduction earlier in the year, and freedom from mermithid nematode parasitism. In the woods of the Apalachicola National Forest, the advantages enjoyed by S. invicta appear to be counteracted by a greater ability of S. geminata newly mated queens to survive the colony founding period. / Comparisons of the reproductive biology of S. invicta and S. geminata indicate striking differences. All mature S. invicta colonies are reproductively active during late spring and early summer, when mating flight activity is at its peak. Subsequently, the number of active colonies and the number of ants participating in mating flights gradually declines. The reproductive system of S. geminata is more complex, with colonies pursuing three different strategies. Two-thirds of the S. geminata colonies are reproductively active only in the late spring and early summer. About one-fifth are active only in the fall. A small number of colonies release alates in the spring/summer and again in the fall. The gynes of S. geminata exhibit a distinct dimorphism: those produced in spring and summer are larger, heavier, and fatter than gynes produced in fall. Both types are successful at becoming the sole queens of mature colonies, although several lines of evidence indicate that microgynes from fall mating flights do not found colonies independently. / Source: Dissertation Abstracts International, Volume: 55-04, Section: B, page: 1269. / Major Professor: Walter R. Tschinkel. / Thesis (Ph.D.)--The Florida State University, 1994.

Genetic models of female-biased sex ratios in subdivided populations include individual selection (inbreeding and sib mating, dispersal, and local mate competition (LMC) that assumes restricted mating among the progeny of a few females) and group selection. I examined two genetic assumptions of these models in a parasitic wasp, Muscidifurax raptor (Hymenoptera: Pteromalidae), a solitary ectoparasitoid of dipteran pupae. These assumptions are (1) sex ratio genotypes produce similar phenotypes over a range of environmental conditions (no genotype-environment interactions), and (2) sex ratio is genetically uncorrelated with other life history traits. / I found variation among five strains in sex ratio and daily fecundity, but there were no strain-environment interactions. The strains all increased the proportion of males with increasing density of ovipositing females. M. raptor is not a pure LMC species. Males emerge before females and await them for mating, but emergence spans 8 days and males are winged and capable of dispersal. Alternative models for sex ratio variation in M. raptor include differential dispersal by males and females and group selection models. / In a diallel analysis of three strains, I found that the genetic variance in sex ratio and other life history traits includes directional dominance, indicating that inbreeding will reduce the bias in sex ratio. I also found dominance genetic correlations and maternal effects correlations among sex ratio, daily fecundity, and development time. Females that develop quickly have higher fecundity and produce more female-biased sex ratios. The correlation is a result of the sequence of sex allocation during an oviposition bout: male eggs are oviposited early whereas females are oviposited later. / Sex ratio in M. raptor is a composite trait that reflects variation in fecundity as well as the propensity to fertilize eggs. The genetic correlations between sex ratio and other life history characteristics indicate that sex ratio may not evolve freely, but is constrained by selection on other traits. / Source: Dissertation Abstracts International, Volume: 51-11, Section: B, page: 5125. / Major Professors: Joseph Travis; Daniel Simberloff. / Thesis (Ph.D.)--The Florida State University, 1990.