Progress 11/01/05 to 10/31/08
Outputs
OUTPUTS: The objective of this study was to understand the recruitment and maintenance of WA dung beetle populations to fields and barns where cattle are kept in high numbers. Dung beetles are important decomposers of cattle dung and can have significant effects on filth fly populations and cattle health in general. We specifically tested the effects of veterinary parasiticide application (e.g. drugs used to control cattle parasites such as Ivermectin). Variation in response to veterinary parasiticides (VPs) indirectly indicates the extent to which resistance by target and non-target insect fauna is possible. We conducted field experiments to quantify the effects of VPs in dung on beetle recruitment, growth, and survival. We have sampled dung beetle populations from eastern and central Washington in fields and barns where cattle are kept. Insect recruitment was assayed using dung baited traps. Experiments were conducted on the recruitment, colonization, and development of dung dwelling insects. A masters student has been working on the project and one undergraduate student was trained in ecological techniques in this project. PARTICIPANTS: Dan Skoczylas (WSU MS student), Keriann Bennett (WSU Undergraduate), Holly Ferguson (WSU IAREC), Douglas Walsh (WSU IAREC, Associate Professor: Collaborator), David Horton (USDA Yakima Agricultural Research Center: Collaborator) TARGET AUDIENCES: scientific community & WA state cattle producers PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The impact of veterinary parasiticides used to control cattle parasites has been shown to affect dung fauna populations. However, studies are needed in the U.S. and particularly in the state of Washington in order to produce guidelines to ensure the recruitment and maintenance of dung organisms. Our research indicates that commercially available and commonly used ivermectin formulations in central Washington (Ivomec and Doramectin) do not affect colonization or development of dung fauna such as flies, parasitoids and dung beetles during the hot and dry summer months from May to September. Further research is necessary to determine if these results are typical. Identification of the Washington state cattle dung insect fauna is an important outcome of this project.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Insect polyphenisms have been shown to be regulated by differences in gene expression from insects as diverse as ants, honeybees and butterflies. However, there are still very few studies that investigate the genetic basis for phenotypic plasticity and my research is necessary to test the general hypothesis that developmental plasticity and evolution depend on gene expression in species that exhibit phenotypic plasticity. To address this problem, my lab studies cell proliferation in insects and the InR pathway in particular. In insects insulin-like peptides secreted primarily by the brain act as whole-animal circulating signals. When these signals reach the imaginal discs, they bind to the insulin receptor and activate a signal transduction cascade that controls the rate of cell proliferation within that disc. This year we have cloned several insulin signaling pathway genes from the large horned beetle, Allomyrina dichotoma, to add to our growing library of beetle insulin
signaling pathway genes. We have also added to our existing fragment of the putatative Onthophagus nigriventris Insulin Receptor gene and plan to have the full length cDNA sequence cloned by the end of 2008. Expression studies on both Onthophagus and Allomyrina are underway using quantitative real-time PCR. To address function of these genes during cell growth and proliferation, we will study the effects of these genes experimentally in the flour beetle, Tribolium castaneum.
PARTICIPANTS: Dan Skoczylas, Holly Ferguson, Douglas Walsh, David Horton (USDA)
TARGET AUDIENCES: Research community.
Impacts
The results of this research will provide important new information about the functioning and regulation of the insulin signaling pathway in insects. This research is important because it will examine the extent to which changes in the nutritional environment are linked with changes in expression of genes in the insulin signaling pathway. In addition to increasing our understanding of insulin signaling in cell growth and proliferation in insects, the research is not only conducted by myself but is also done by trainees, both graduate and undergraduate as well as high school students in the summer.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
The expression of virtually all insect morphological traits is sensitive to nutrition, yet almost nothing is known about the genetic mechanisms that couple trait growth with nutrition. An extreme example occurs in the horns of scarab beetles. Within a single species, beetle horns can vary tremendously in size and shape due to differential larval access to nutrition. Beetles with horns include some of the most magnificent and bizarre organisms alive today. The sizes of these horns (relative to the sizes of the beetles that bear them) can dwarf even the most extreme antlers of ungulates, and the diversity of horn forms is breathtaking. Thus, beetle horns are conspicuous morphological structures of known functional significance, and the more than a century of interest and observation of these animals, combined with recent behavioral studies, provide a rich ecological context for our study of horn development. The long-term goal of this research project is to understand
the ways that physiology, genetics, and development interact with the environment to generate diversity in animal forms. My specific aims are to determine the extent to which (1) the insulin receptor pathway couples trait growth with nutrition in horned beetles, (2) the insulin receptor pathway and the limb-patterning pathway regulate male dimorphism and sexual dimorphism in horn expression, and (3) the limb-patterning pathway specifies horn shape in beetles with divergent horn morphologies.
Impacts
The results of this study will provide important new information about how the mechanisms of insect development may be modified to generate biologically meaningful - even spectacular - variation in animal form. In this way, our study will address fundamental and long-standing questions in biology such as: How do novel and complex morphological structures arise? And how are these traits modified to generate diversity in animal form? A core objective of this research is the cross-training of young scientists in development, genetics, and evolution. Both graduate and undergraduate students are involved with this project and will be trained in developmental and genetic methods alike. Numerous aspects of this study lend themselves to independent undergraduate student projects, and the PI is committed to training students in all aspects of the research process including writing and presenting results at local and national meetings. Corley has trained 4 female undergraduates
and also teaches low-income high school Hispanic and Native American students in a genetics summer course for Washington State Unviersity (WSU) Upward Bound. Two of the focal species in this project are very large rhinoceros beetles and worldwide favorites of museums and classrooms, which are perfect for a range of educational programs. I intend to use these animals in a variety of educational/outreach activities including visiting local school classrooms in WA and supporting the WSU Insect Museum.
Publications
- Corley, L., S.Cotton, E.McConnell, T.Chapman, K.Fowler, and A.Pomiankowski. 2006. Highly variable sperm precedence in the stalk-eyed fly Teleopsis dalmanni.. BMC Evolutionary Biology 6:53-59.
- Emlen, D.J., Q.Szafran, L.Corley, and I.Dworkin. 2006. Candidate genes for the development and evolution of beetle horns. Heredity. 97:179-191.
- Corley, L., and M.D.Lavine. 2006. A review of insect stem cell types. Seminars in Cell & Developmental Biology. 17:510-517.
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