The purpose of this project was to evaluate diflubenzuron ovicidal effects on adult female alfalfa weevils " Hypera postica in the laboratory. There was little relationship of weevil mortality to dosage or length of exposure of the adult to the chemical. An indirect result of diflubenzuron was an increase in muscardine fungus (Beauveria Sp.). Other effects of the chemical on the adults were yellow deposits and tissue extending from the tip of the abdomen. The main effect of dilfubenzuron when fed to female alfalfa weevils was on the eggs. The effects were dosage related, especially on eggs viability. The viability was dropped from 99% in the control to 38.9% on the treated insects in ten days using the highest dosage. Another effect of diflubenzuron on alfalfa weevil eggs was on the shape of the eggs. The treated insects laid longer and lighter color eggs.

No description available.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 11, 2008) Includes bibliographical references.

No description available.

The pales weevil, Hylobius pales (Herbst), and the deodar weevil, Piss odes nemorensis Germar, are regeneration pests of pine plantations in the eastern United States. Attempts to sample regeneration weevils in Virginia have met with little success. Two trap types were field tested to determine their effectiveness in sampling H. pales and P. nemorensis populations in Virginia Christmas tree plantations. Labor intensive pit traps, using natural host materials and synthetic volatiles, caught significantly more weevils than PVC pitfall traps baited with synthetic volatiles alone. No differences in trap catches were observed between stationary and rotated traps. Vegetation management had no effect on trap catch. However, it was observed that newly planted white pine seedlings (Pinus strobus L.) were fed upon by H. pales at Significantly higher rates in plots not managed for competing vegetation than in herbicide treated plots. Feeding activity in mowed plots was intermediate. Trap catch did not correlate with seedling damage within or among sampling periods, or between years. The seasonal activity of both species is reviewed in detail. Mark-and-recapture techniques used to assess trap efficacy showed traps baited with pine material were most effective, irrespective of trap type. The response of H. pales adults to different ethanol-and-turpentine ratios in a laboratory bioassay did not vary with respect to gender or age. No gender differences in response to treatments were observed in these studies. / Master of Science

<p>Asexual reproduction and polyploidy are relatively rare in animals with chromosomal sex determination and always represent a derived condition. To accomplish asexual reproduction several changes in gene expression are required in the mechanism of oogenesis. Polyploidy increases the cell volume and also gives rise to alterations in general physiology. Nevertheless, there are asexual animals that not only survive but seem to be doing better than their sexual progenitors. This is expressed in the distribution pattern called geographical parthenogenesis. Using molecular phylogeny, I here examine the evolution of Otiorynchid weevils, mainly <i>Otiorhynchus scaber</i> and <i>sulcatus</i> in an attempt to trace the evolutionary history and find out what causes the variation in success of different parthenogens. I also evaluate the contribution of asexuality, hybridity and polyploidy as explanations behind geographical parthenogenesis in insects. I conclude that what is called <i>O. scaber</i> is, in fact, a set of geographical polyploids as polyploidy and not asexuality explains the difference in clonal success. I also argue that <i>O. sulcatus</i> is a recently formed clonal species of non-hybrid origin that may well be a good example of a true general purpose genotype. I find little support for asexuality or a hybrid origin as explanations behind geographical parthenogenesis in insects. Finally, I argue that polyploidy in all eukaryotes should be seen as an opportunity for the species evolution, not as a limitation that ensures the demise of the taxa.</p>

Asexual reproduction and polyploidy are relatively rare in animals with chromosomal sex determination and always represent a derived condition. To accomplish asexual reproduction several changes in gene expression are required in the mechanism of oogenesis. Polyploidy increases the cell volume and also gives rise to alterations in general physiology. Nevertheless, there are asexual animals that not only survive but seem to be doing better than their sexual progenitors. This is expressed in the distribution pattern called geographical parthenogenesis. Using molecular phylogeny, I here examine the evolution of Otiorynchid weevils, mainly Otiorhynchus scaber and sulcatus in an attempt to trace the evolutionary history and find out what causes the variation in success of different parthenogens. I also evaluate the contribution of asexuality, hybridity and polyploidy as explanations behind geographical parthenogenesis in insects. I conclude that what is called O. scaber is, in fact, a set of geographical polyploids as polyploidy and not asexuality explains the difference in clonal success. I also argue that O. sulcatus is a recently formed clonal species of non-hybrid origin that may well be a good example of a true general purpose genotype. I find little support for asexuality or a hybrid origin as explanations behind geographical parthenogenesis in insects. Finally, I argue that polyploidy in all eukaryotes should be seen as an opportunity for the species evolution, not as a limitation that ensures the demise of the taxa.

The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-free Prince Edward Islands represent ideal ecosystems for addressing questions relating to the partitioning of potential influences of anthropogenic changes, such as climate change and alien species on ecosystem functioning. Consequently, weevil species were used in the present investigation to address questions of morphological change over time with reference to climate change and mouse predation. As a prelude to the assessment of morphological changes over time, the six currently recognised weevil species, namely, Bothrometopus randi, B. parvulus, B. elongatus, Ectemnorhinus similis, E. marioni and Palirhoeus eatoni from both Marion and Prince Edward Islands were confirmed by morphometric analyses. However, the taxonomic status of Ectemnorhinus weevil species on both islands is much more complex than previously considered. A multi-faceted approach based on both morphometric and molecular (COI gene) data suggest the presence of a single species, comprising diverse, genetically discrete populations on Marion Island and two genetically distinct species on Prince Edward Island. The assessment of morphological changes over time included the four remaining weevil species (B. elongatus, B. randi, B. parvulus and P. eatoni) occurring on both Marion and Prince Edward Islands, collected non-consecutively over five decades. These analyses suggest morphometric size differences between samples from both Marion and Prince Edward Islands collected in the mid-1960s and 1970s and those collected recently. Similarly, samples from both islands collected in the early- to mid-1980s also showed morphometric shape differences with those collected recently for both Prince Edward and Marion Islands, respectively. Generalized Linear Models (GLZ) suggested year of sampling to contribute more, to both, morphometric size and shape in all species sampled on both islands, while temperature contributed more to shape for species collected on Marion Island. Given the consistent pattern of morphological change over time for both the mouse-infested Marion Island and the mousefree Prince Edward Island, it is possible that climate change rather than mouse predation may primarily influence weevil morphological changes on the two islands. Subsequent analyses extended the question of weevil morphological changes over time with reference to climate change and mouse-predation, and included sub-fossil weevil elytra and head capsule remains collected on Marion Island mire habitats. As a prelude to these analyses, an attempt was made to first identify the sub-fossil samples (using head capsules) with reference to recent samples of the currently recognised weevil species on both islands. While species-level identifications were not possible, morphometric analyses suggest that the sub-fossil remains belong to the Ectemnorhinus group of weevils. Sub-fossil weevil remains recovered in mire sediments from 2 m and 2.5 m depths, considered to represent different dimensions in space and time, were dated at 789 BC and 2331 BC, respectively. Subsequent analyses showed no significant morphometric changes in sub-fossil material between the various depths, predating the effects of climate change on both islands and the introduction of the house mouse (Mus musculus) on Marion Island in the early 1800s. However, a comparison between the sub-fossil remains and recently collected material considered to represent a period characterised by climate change and mouse-predation showed significant morphometric differences over time. However, the questions investigated in this study need to be investigated further because the potential ecological influences driving ecosystem functioning on the islands may be much more complex than currently understood. / Thesis (PhD (Entomology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

A biological investigation of the apparently intimate and mutually relationship exist­ing between certain plant-like micro-organisms and certain insects. The literature of the subject is briefly re­viewed and discussed and a critical appraisal of previous work is made. A problem, the association of certain micro-organisms with two species of grain feeding wee­vils, is discussed in greater detail and a method of approach is proposed and analysed. Studies of the micro-organisms in vivo and in vitro are described in conjunction with investigations, by experimental techniques, of the associa­tion of the micro-organisms and the weevils. Findings are discussed and conclusions are presented. / Thesis / Doctor of Philosophy (PhD)

This thesis presents a study into structural colours that exist in natural samples, the principle aim of which is to produce experimental methods by which these colours may be examined and evaluated. In order to achieve this, previously observed structures are described, electromagnetic theory is summarised and a series of samples are examined constituting examples of the structures present in nature. The first sample discussed is the multilayer in the epicuticle of the buprestid beetle, C. raja. In order to evaluate the refractive indices of the layers contained within this structure, existing optical techniques are used to establish absolute reflection spectra for a number of angles of incidence in both linear polarisations. The approximate design for the structure is obtained by electron microscopy and modelled using Fresnel's equations. This model is then refined by a recursive least squares fitting routine to obtain the refractive indices. The second sample is the diffuse white scattering structure in the scales of two white beetles, Lepidiota stigma and Cyphochilus spp. The reflection from these scales is measured and found to be brilliantly white due to the irregular internal structure of the scales. Comparison of the Fast Fourier Transforms of TEM images of the internal structure with the diffraction pattern obtained from monochromatic laser light diffracting through a single scale demonstrate a link between this structure and photonic effects. The third sample type are found in the scales of the large true weevils, Eupholus schoenherri pettiti and E. magnificus. These scales are shown to have a domained structure in which the domains were oriented differently to each other. Single domains are shown to exhibit different colours at different orientation. The final sample is the highly regular 2-dimensional diffraction grating observed in a marine diatom, Coscinodiscus wailesii. Diffraction is demonstrated by measuring the in-plane diffraction from a single frustule for both monochromatic laser light and white light, showing an enhanced transmission for red wavelengths. Subsequent imaging of the transmitted diffraction pattern allows for the calculation of the transmitted power in each diffracted order.