Theses and Dissertations at Montana State University (MSU)
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Item Overcoming the challenges of tamarix management with Diorhabda carinulata through the identification and application of semiochemicals(Montana State University - Bozeman, College of Agriculture, 2018) Gaffke, Alexander Michael; Chairperson, Graduate Committee: David K. Weaver; Sharlene E. Sing, Tom L. Dudley, Daniel W. Bean, Justin A. Russak, Agenor Mafra-Neto, Paul A. Grieco, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Semiochemicals to enhance herbivory by Diorhabda carinulata aggregations in saltcedar (Tamarix spp.) infestations' in the journal 'Pest management science' which is contained within this thesis.; Sharlene E. Sing, Tom L. Dudley, Daniel W. Bean, Justin A. Russak, Agenor Mafra-Neto, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Field demonstration of a semiochemical treatment that enhances Diorhabda carinulata biological control of Tamarix spp.' submitted to the journal 'BioControl' which is contained within this thesis.; Sharlene E. Sing, Tom L. Dudley, Daniel W. Bean, Justin A. Russak, Agenor Mafra-Neto, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Allee effects and aggregation pheromones: new releases of Diorhabda carinulata remain longer in the presence of pheromone formulations' submitted to the journal 'Biological Invasion' which is contained within this thesis.; Sharlene E. Sing, Jocelyn Millar, Tom L. Dudley, Daniel W. Bean, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Behavioral responses of Diorhabda carinulata adults to repellent compounds isolated and identified in volatiles collected from conspecific larvae' submitted to the journal 'Journal of chemical ecology' which is contained within this thesis.The northern tamarisk beetle, Diorhabda carinulata (Desbrochers), is an approved and established classical biological control agent for saltcedars (Tamarix spp.). Adequate control of Tamarix has not yet been achieved in certain areas where D. carinulata has been released. Retaining beetle populations on sites where it has been released is problematic, and accurately monitoring D. carinulata populations to determine successful establishment is difficult. Negative, indirect impacts have also resulted from the agent's establishment outside targeted treatment areas in the southwestern United States. Manipulation of D. carinulata spatial distribution with semiochemicals could potentially resolve or ameliorate these and other operational issues. Lures utilizing a specialized wax based matrix for the controlled release of semiochemicals were impregnated with a previously identified pheromone and/or behaviorally active host plant volatiles known to stimulate aggregation in D. carinulata. Emission of these compounds from the matrix was characterized using a push-pull volatile collection system, and quantified using gas chromatography-mass spectrometry. Observed release rates confirm that semiochemicals lures formulated with this matrix are a viable option for facilitating aggregation of D. carinulata under field conditions. The results of field-based assays indicate saltcedars treated with this semiochemical delivery system attracted and retained higher densities of D. carinulata than Tamarix that received a control (semiochemical free) lure. Higher densities of both adult and larval D. carinulata were recorded on treated plants. Semiochemically treated Tamarix plants also exhibited more damage, resulting in a greater decrease in canopy volume than control trees. The attraction and retention of D. carinulata to these species-specific semiochemicals on treated Tamarix plants also arrested the dispersal of newly released individuals, resulting in greater population growth. Repellent semiochemicals were also investigated for their potential to manipulate spatial distributions of D. carinulata in the field and behavioral assays conducted with reproductive adults demonstrated the ability of larval produced compounds to repel conspecific adults. These results indicate that semiochemical-impregnated media could be useful for detecting, retaining, and directing populations of D. carinulata. The use of semiochemicals could be used to potentiate low density populations, increase monitoring efficacy, retain adults on release sites, and repel D. carinulata from sensitive habitat.Item Olfactory preference and reproductive isolation of two Mecinus species (Coleoptera: curculionidae): implications for biological control of dalmatian, yellow, and hybrid populations of Toadflax, Linaria species(Montana State University - Bozeman, College of Agriculture, 2016) Hubbard, Charles Eli; Chairperson, Graduate Committee: David WeaverClassical biological control of the exotic, invasive toadflaxes Linaria vulgaris (L.) Mill. and Linaria dalmatica Mill. has had both successes and failures. One of the new challenges land managers face is the apparent increase in vigor shown by naturally occurring hybrid populations of the two toadflax species. This has presented practical problems because managers now are unable to decide which weevil species to use on these hybrids: Mecinus janthinus, which is found on L. vulgaris, or M. janthiniformis which has preference for L. dalmatica. This key question was addressed using olfactometer experiments to determine if the volatile profile for each plant establishes host fidelity for the naturally-occurring associated Mecinus species. Adults of both insect species were paired in cages on clones of naturally occurring and synthetic reciprocal cross hybrids and the parent toadflax species to quantify mating events and to determine the number of offspring produced on clones of each plant type of plant in incomplete randomized blocks. We did this using both intraspecific and interspecific pairs of Mecinus species to determine how many offspring are produced by intraspecific adults and also to explore the possibility of establishing a hybrid weevil population using clones of each plant type. Host plant preference for both Mecinus species is influenced by olfactory responses, but this was only evident for adult females. Our first series of no-choice experiments with intraspecific mating pairs indicated that M. janthiniformis is more successful in terms of offspring produced for all types of hybrid toadflax tested. The results also showed that M. janthinus had a higher percentage of survival on all types of hybrids. As expected each Mecinus species performed best on its natural host plant. The results of our second series of no-choice experiments suggest that these two weevil species can produce viable interspecific offspring on clones of most of the plant types evaluated. This suggests that the newly described M. janthiniformis is very similar to M. janthinus and the separation between the two species is controlled at least in part, by olfactory cues from the favored host. In the future, land managers can better decide which Mecinus species to use based on whether the hybrid weed species is influenced more by L. vulgaris, or L. dalmatica.Item Laboratory fecundity and development, field population dynamics, pupal predation and the history of releases of the spurge hawkmoth, Hyles euphorbiae (L.), a biological control agent of leafy spurge, Euphorbia esula L., in Montana(Montana State University - Bozeman, College of Agriculture, 1988) Poritz, Noah HollemanItem Virulence and dissemination enhancement of a mycoherbicide(Montana State University - Bozeman, College of Agriculture, 1999) Tiourebaev, Kanat SlyambekovichItem A study of Urophora affinis (Diptera : Tephritidae) released on spotted knapweed in Western Montana(Montana State University - Bozeman, College of Agriculture, 1976) Story, Jim MaynardItem Effects of Brachypterolus pulicarius on growth and seed production of Dalmation toadflax(Montana State University - Bozeman, College of Agriculture, 1998) Grubb, Robert ThomasItem Age-specific life table studies of potential strains or host races of Calophasia lunula (Lepidoptera: Noctuidae) (Hufn.) reared on Dalmation toadflax, Linaria genistifolia ssp. dalmatica (L.) Maire and Petitmengen, or yellow toadflax, Linaria vulgaris (Mill.)(Montana State University - Bozeman, College of Agriculture, 1995) Breitenfeldt, Todd AlanItem Molecular characterization of foreign and domestic isolates of Rhizoctonia solani for the biological control of leafy spurge Euphorbia esula(Montana State University - Bozeman, College of Agriculture, 1998) Nash, Deanna LynneItem The effects of mowing and of spraying musk thistle on the biological control agent Rhinocyllus conicus(Montana State University - Bozeman, College of Agriculture, 1978) Miller, Timothy JohnItem Determination of host races in three insect species attacking Dalmatian toadflax and yellow toadflax in North America(Montana State University - Bozeman, College of Agriculture, 1991) McDermott, Gregory James