Browsing by Subject "Biological Control"
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Item Compatibility of biological and cultural control in dairy heifer group housing(2015-01) Starcevich, JessicaThe compatibility of biological and cultural fly control on dairies was examined in three ways. First, a review of the current literature concerning filth fly production and filth fly pupal parasitoids on dairies was conducted to asses where there was a lack of information. Second, a survey of filth fly species and their pupal parasitoids was conducted on six organic dairies in Wisconsin and Minnesota to determine where on dairies both filth flies and their pupal parasitoids were most commonly breeding. Third, filth fly production and efficacy of their pupal parasitoids was examined in three different commercially available bedding materials in a heifer rearing facility in southern Minnesota in 2009 and 2010.Item Host range and disease dynamics of viral pathogens of common carp (Cyprinus carpio), and their potential as biological control agents(2022-11) Tolo, IsaiahCommon carp (Cyprinus carpio), hereafter referred to as carp, is a ubiquitous and destructive invasive fish in Minnesota and much of the world. There is a need for the development of species-specific, highly effective, and cost-efficient approaches for carp management that can be used across large scales. Pathogen biocontrol agents have previously been used in combination with conventional methods to control vertebrate pests at the landscape scale. Cyprinid herpesvirus 3 (CyHV-3; aka. Koi herpesvirus, KHV) and carp edema virus (CEV) are pathogens worthy of further investigation for carp biocontrol due to their host-specific pathogenicity. Both CyHV-3 and CEV are known to cause mass mortality events of carp and it is possible that carp populations can continue to decline after initial outbreaks. Despite the potential value of viruses as biocontrol agents, there are significant data gaps in the understanding of the distribution and disease ecology of carp-specific viruses in North America, a need for increased research capacity, as well as concern related to the risks of using microbial biological control agents in general. This dissertation is composed of research working to identify a safe and effective pathogenic biocontrol agent for carp. This work contributes to the understanding of the potential value of viral biocontrol of carp by identifying the distribution of CyHV-3 and CEV in Minnesota, obtaining a regional viral strain of CyHV-3 from a carp mortality event, assessing the host range and disease dynamics of these viruses, and by describing the natural ecology of CyHV-3 in laboratory disease trials and wild populations surveys.Item The role of entomopathogenic fungi in the management of Soybean Aphid.(2011-07) Koch, Karrie AnneSoybean aphid, Aphis glycines Matsumura, is an invasive arthropod pest of soybean which has been present in North America since 2000. Aphid outbreaks cause economic damage via increased insecticide use and reduced yield. Management of this pest has been achieved almost exclusively with foliar applications of broad spectrum insecticides. The purpose of this research is to determine how a fungal pathogen of soybean aphid, Pandora neoaphidis, can contribute to the natural regulation of aphid populations. Pandora neoaphidis is an endemic aphid pathogen and the most frequently reported pathogen infecting soybean aphid. Analysis and field validation of a mathematical model describing the soybean aphid-P. neoaphidis pathosystem has shown that the fungus can establish and persist when aphid densities are lower than the economic threshold of 250 per plant; thus confirming that P. neoaphidis is capable of contributing to aphid control before aphids reach damaging densities. Additionally, field experiments demonstrate that emerging aphid management tactics including aphid-resistant soybean plants and insecticide seed treatments have minimal impacts on aphid infection rates by P. neoaphidis and are likely compatible with this natural enemy. Cage studies demonstrate that the presence of Harmonia axyridis in soybean aphid colonies also harboring P. neoaphidis has no impact on aphid infection by the fungus. Pandora neoaphidis may also be an important regulator of aphid populations on the aphids’ primary host, Rhamnus cathartica, or common buckthorn, as soybean aphid morphs which occur on this host are the most susceptible to infection. However, fungicide applications to soybean can have lasting impacts on the beneficial fungi infecting soybean aphid as foliar fungicide applications to soybean reduced the rate of aphid infection both before and after aphids moved to the primary host in the autumn. In summary, P. neoaphidis is likely an important member of the natural enemy community which provides a significant level of aphid biological control.Item Wasps, vampires, and carrion flies: addressing the safety of the parasitoid Conura annulifera (Hymenoptera: Chalcididae), a promising biological control agent for the Galapagos Islands.(2023-12) Ramirez, IsmaelThe avian vampire fly, Philornis downsi (Diptera: Muscidae), is an invasive species in the Galapagos Islands that has caused significant mortality among endemic bird species. This thesis delves into the safety of the neotropical wasp Conura annulifera (Hymenoptera: Chalcididae) as a biological control agent against the avian vampire fly in the Galapagos Islands and encompasses four chapters addressing such safety. Chapter one scrutinizes the ecological specificity of pupal parasitoid species found in the native range of the avian vampire fly and other fly species in mainland Ecuador using food web analysis. Additionally, in Chapter two, I comprehensively characterized the composition of the carrion fly community in the Galapagos Islands, encompassing the abundance and distribution of both endemic and introduced species. Furthermore, I investigated the potential for competitive interactions between introduced and endemic carrion fly species and their implications for biological control. In Chapter Three, I examine the burrowing behavior of endemic and introduced carrion fly species in the Galapagos Islands and evaluate the ability of C. annulifera to locate and attack subterranean puparium as the soil is an effective barrier that provides refuge for non-target species that burrow. Finally, in Chapter Four, I assess the physical host preference of C. annulifera and its potential to parasitize non-target carrion fly species using no-choice trials in containment facilities of the Charles Darwin Research Station in the Galapagos Islands. The findings of this thesis provide informative insights into the intricate ecological interactions between the avian vampire fly, C. annulifera, and carrion fly species in the Galapagos Islands and Mainland Ecuador. Additionally, it sheds light on the safety of C. annulifera to serve as a biological control agent for the avian vampire fly. This knowledge is crucial information to decision-making officials regarding the potential introduction of C. annulifera to the Galapagos Islands to mitigate the detrimental effects of P. downsi on endemic bird populations and possible extinctions.