Doctor of Philosophy / Department of Entomology / Alberto B. Broce / Ludek Zurek / Stable flies, Stomoxys calcitrans (L.), are a serious pest to beef cattle in confined animal feeding operations (CAFOs) by causing economic losses in the form of reduced feed intake and feed efficiency, resulting in reduced weight gain. Integration of sanitation, parasitoids, and residual insecticides offers a much-needed reduction of this pest's impact on CAFOs. In the past two decades, stable flies have become the most important pest of pastured cattle. Further impact that stable flies have on cattle is when cattle seek protection from stable flies by standing in water, which results in water pollution with fecal matter, in addition to reduced foraging time. Sites of winter feeding of round hay bales have demonstrated to be important habitats for stable fly development during spring/summer. Cattle feeding on round bales can waste as much as 40% of the total amount of hay when fed in conventional ring feeders. Hay wastage is largely a function of the type of feeding method and the amount of agonistic behavior of the cattle. Feeding methods range from rolling hay directly onto the ground to the use of various types of feeders. Since traditional control methods utilized in CAFOs against stable flies have not been evaluated in pastures, producers rely heavily on organic insecticides in efforts to control this pest. At this time, there are no effective control methods available for stable fly management on pastured cattle. This research examined different management strategies that could minimize or eliminate stable fly larval habitats by reducing the amount of hay wasted being mixed with manure. In addition, different hay and manure mixtures were compared to characterize the larval habitat at these hay-feeding sites. Finally, the efficacy of boric acid, Metarhizium anisopliae, and tetrachlorvinphos in controlling the development of stable flies in hay substrates was evaluated.

Doctor of Philosophy / Department of Entomology / Ludek Zurek / Enterococci are a group of commensal bacteria that are important nosocomial pathogens. They are abundant in human sewage and wastewater treatment facilities (WWTF). This study focused on the role of house flies, Musca domestica, in the ecology of enterococci at WWTF in both field and laboratory experiments. The first study objective focused on sampling and characterizing enterococci from house flies and wastewater sludge from four WWTF in northeastern Kansas. Enterococci were quantified, identified, and screened for antibiotic resistance and virulence traits, and genotyped. The profiles of enterococci (spp. diversity, antibiotic resistance and virulence) from WWTF sludge and the house flies were similar, indicating that the flies successfully acquired the bacteria from the WWTF substrate. Enterococci with the greatest amount of antibiotic resistant and virulence traits originated from the WWTF that processed meat waste from a commercial sausage plant. Genotyping of E. faecalis revealed clonal matches from sludge and house flies. The second study objective involved tracking the fate of E. faecalis in the digestive tract of house flies in laboratory assays. Colony forming unit (CFU) counts were highest in the midgut at 1 h and declined during the first 24 h. In the labellum, foregut and hindgut, E. faecalis concentrations were more variable but were overall higher after 24 h. Observations from CFU counts and visualizations under a dissecting microscope revealed that E. faecalis peaked in the crop after 48 h suggesting active proliferation in this region. The third objective of the study involved tracking the emergence of calyptrate muscoid flies from stockpiled biosolid cake at one of the four WWTF. Traps were employed at the site for a total of 47 weeks, totaling 386 trap-weeks. A total of 11,349 calyptrate muscoid flies were identified with the two most common species being stable flies (Stomoxys calcitrans) (9,016, 80.2%) and house flies (2022, 18.0%). Numbers of stable flies and house flies peaked around mid-July each year and a second, smaller peak was observed for stable flies 5-8 weeks later. Estimated annual emergence of stable flies was 551,404 and for house flies 109,188.

The stable fly, Stomoxys calcitrans (L.) is a haematophagous fly that feeds primarily on the forelegs of cattle stimulating a range of avoidance behaviours in confinement situations such as feedlots. From literature it is apparent that stable flies associated with feedlots have a significant impact on cattle especially with regard to economic parameters such as a decline in feed intake and thus a lower average daily gain resulting in less meat production due to irritation caused by painful bites. The abundance of the stable flies was studied in a large commercial feedlot near Heidelberg from October 2012 to September 2013. Two tsetse fly traps, namely the NZI and the Vavoua fly traps, were used and evaluated in determining the seasonal abundance of the stable flies. The tsetse traps proved to be most effective for sampling stable flies compared to other designs. The NZI and Vavoua tsetse type trap were compared and although there were no significant difference the NZI trap proved to be more reliable and user friendly for this study. Stable flies were more abundant from late December with a peak in numbers late in January through February and became less abundant from early March. Minimum to no fly abundance occurred in the winter months from May to June 2013. The data indicated a strong edge effect for the stable flies, the flies were more abundant in pens and corridors that were surrounded by vegetation, manure run off and holding ponds. The numbers collected in traps were correlated with stable fly counts on the cattle to be used in calculating a future threshold in chemical control. Preliminary observations on the influence of temperature, wind speed and rainfall were also made. This research will form part of a larger project to determine an integrated fly management program for the feedlot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

The stable fly, Stomoxys calcitrans (L.) is a haematophagous fly that feeds primarily on the forelegs of cattle stimulating a range of avoidance behaviours in confinement situations such as feedlots. From literature it is apparent that stable flies associated with feedlots have a significant impact on cattle especially with regard to economic parameters such as a decline in feed intake and thus a lower average daily gain resulting in less meat production due to irritation caused by painful bites. The abundance of the stable flies was studied in a large commercial feedlot near Heidelberg from October 2012 to September 2013. Two tsetse fly traps, namely the NZI and the Vavoua fly traps, were used and evaluated in determining the seasonal abundance of the stable flies. The tsetse traps proved to be most effective for sampling stable flies compared to other designs. The NZI and Vavoua tsetse type trap were compared and although there were no significant difference the NZI trap proved to be more reliable and user friendly for this study. Stable flies were more abundant from late December with a peak in numbers late in January through February and became less abundant from early March. Minimum to no fly abundance occurred in the winter months from May to June 2013. The data indicated a strong edge effect for the stable flies, the flies were more abundant in pens and corridors that were surrounded by vegetation, manure run off and holding ponds. The numbers collected in traps were correlated with stable fly counts on the cattle to be used in calculating a future threshold in chemical control. Preliminary observations on the influence of temperature, wind speed and rainfall were also made. This research will form part of a larger project to determine an integrated fly management program for the feedlot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014