No description available.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Invasive arthropod predators are one of the largest and most diverse groups of invasive insects in the world. Many are generalist predators, with cosmopolitan distributions due to their use as biological control agents in agriculture. Harmonia axyridis (Coleoptera: Coccinellidae), an invasive arthropod predator species native to Asia, which now has a world-wide distribution. It is considered one of the most successful biological control predator species and is generally considered to be economically beneficial. However, negative effects have recently emerged in agricultural and natural systems. Harmonia axyridis poses a threat to biodiversity as it outcompetes native species for food resources. It can also feed directly on native predatory arthropods that disrupt natural ecosystem processes. Their movement in-and-out of agricultural landscapes may depend on food availability with natural vegetation alongside agricultural areas often utilised for refuge and alternative food resources. This beetle has also been recorded in urban areas. The aim of this study was to determine how the invasive H. axyridis beetle uses the local landscape in the Western Cape province, South Africa, and to determine its threat to native species. I sampled urban landscapes, vineyards, natural vegetation/vineyard edge zones and pristine natural areas for arthropods every second month using a suction sampler. Data collected included the abundance and diversity of H. axyridis, herbivores, local predators and non-Harmonia ladybeetles. Most H. axyridis were collected in urban areas during all sampling periods. Highest abundance was recorded in May and July (winter). This indicates that urban areas were the preferred landscape feature and that these act as ovipositing areas, particularly as larval H. axyridis were also only collected in urban areas. Significantly, vineyards and natural vegetation had very low abundance of H. axyridis, questioning their value as a biological control agent in this region. Harmonia axyridis had a negative effect on the overall local arthropod community, as well as the predator and herbivore guilds, although it was positively correlated with the abundance of non-Harmonia ladybeetles. This suggests that H. axyridis and non-Harmonia ladybeetles are responding to the same resources in these landscapes. A negative correlation found between H. axyridis and the abundance of predators is most likely due to competition for the same resources (e.g. prey items). These negative impacts, along with their negligible value as biological control agents in agriculture, suggest that a programme should be implemented to control this invasive species. More specifically, control should be aimed in urban areas during winter when and where the species aggregates and when larvae are present. / AFRIKAANSE OPSOMMING: Geleedpotige roofdiere is een van die grootste en mees diverse groepe van uitheemse insekte in die wêreld. Die meeste is veelsydige roofdiere, met wêreldwye verspreiding te danke aan hul gebruik as biologiese beheer agente in landbou gebiede. Byvoorbeeld, Harmonia axyridis (Coleoptera: Coccinellidae), 'n indringer geleedpotige roofdier spesies inheems aan Asië, het nou 'n wêreldwye verspreiding. Dit word beskou as die mees suksesvolle roofdier spesies wat gebruik word vir biologiese beheer en word oor die algemeen beskou as ekonomies voordelig. Negatiewe effekte was onlangs aangeteken beide in landbou gebiede en natuurlike areas. Harmonia axyridis hou 'n bedreiging in vir inheemse biodiversiteit as dit inheemse spesies uitkompeteer vir voedsel bronne. Dit kan ook direk voed op plaaslike roofsugtige geleedpotiges wat trofiese vlakke ontwrig en uiteindelik, biodiversiteit. Hulle beweging in-en-uit landbou landskappe kan gekoppel word aan die beskikbaarheid van voedsel, en gebruik natuurlike plantegroei langs landbou gebiede dikwels as 'n toevlugs oord en area vir alternatiewe voedsel bronne. Harmonia axyridis word ook in stedelike gebiede aangeteken. Die doel van hierdie studie was om te bepaal hoe die indringer Harlekynkewer die plaaslike landskap gebruik met die fokus op wingerde in die Wes-Kaap provinsie van Suid-Afrika, en tweedens om die bedreiging wat hierdie kewer moontlik vir inheemse spesies te bepaal. Ek het arthropoda in stedelike landskappe, wingerde, natuurlike plantegroei / wingerd rand sones en ongerepte natuurlike areas elke twee maande met behulp van 'n D-vac versamel. Monsters was ontleed deur gebruik te maak van die getalle van H. axyridis, herbivore, plaaslike roofdiere en nie-Harmonia liewenheers kewers. Die meeste H. axyridis was in stedelike gebiede versamel gedurende al die seisoene, maar meeste individue was gedurende Mei en Julie (winter) versamel. Hierdie toon dat stedelike gebiede die voorkeur-landskappe is vir hierdie kewers en dat hierdie gebiede opgetree as eierleggende gebiede, veral omdat larwes van H. axyridis slegs in hierdie gebiede aangeteken was. Wingerde en die natuurlike plantegroei het baie lae getalle H. axyridis gehuisves wat hul waarde as biobeheermiddel bevraagteken. Harmonia axyridis het 'n negatiewe uitwerking op die algehele plaaslike geleedpotige gemeenskappe gehad, asook op die die roofdier en herbivoor gildes, maar hul getalle was positief gekorreleer met die getalle van nie-Harmonia liewenheerskewers. Dit dui daarop dat H. axyridis en nie-Harmonia liewenheerskewers beide reageer op dieselfde hulpbronne in hierdie landskappe. 'n Negatiewe korrelasie was gevind tussen die getalle van H. axyridis en die getalle van ander predatoriese geleedpotiges at waarskynlik te danke was aan mededinging tussen hierdie groepe vir dieselfde hulpbronne (bv prooi). Hierdie negatiewe invloede, asook hul verminderde waarde as biobeheeragente in die landbou, dui daarop dat 'n program in werking gestel moet word om hierdie indringerspesies te beheer. Meer spesifiek, beheer moet gedurende die winter en in stedelike gebiede geskied, waar en wanneer hierdie spesie op sy volopste is en waar larwes teenwoordig is.

Lake trout (Salvelinus namaycush) were extirpated from Lake Champlain around 1900 and from the lower four Great Lakes by 1960. Their ecological, commercial and recreational importance has prompted extensive restoration efforts. Despite widespread evidence of natural reproduction by stocked lake trout, there is minimal evidence of survival of wild progeny beyond age-0. Various abiotic and biotic impediments may be preventing self-sustaining lake trout populations from becoming established. Unsuccessful restoration in shallow areas has recently prompted a shift to restoration efforts to offshore, deep reefs in the Great Lakes. The first objective of this study was to develop, test, and implement methods for evaluating lake trout reproduction in deep water, where previously established techniques were ineffective. The second objective addressed the recruitment bottleneck between the emergent fry and juvenile life stages in Lake Champlain, by assessing the severity of predation on lake trout fry by epi-benthic fish. In order to quantify egg density on deep-water habitats (>18 m), we paired a deep-water egg trap with egg bags to establish a relationship between the two types of gear in Lake Champlain. There was no significant difference between densities in the egg bags and deep-water traps, but there was a positive correlation of their ranks (correlation coefficient = 0.514, p<0.0001). The deep-water traps were then used in Lake Michigan to successfully acquire the first egg density data from two sites on the deep Mid Lake Reef Complex. A drop electroshocker was developed to detect fry presence and tested in Lake Champlain in conjunction with emergent fry traps. Both types of gear exhibited similar patterns of fry relative abundance. To assess fry predation in Lake Champlain, two-hour gillnet sets during the period of fry emergence to identify fry predators and to describe how predation patterns changed diurnally and temporally. Seven species of epi-benthic fry predators were identified, including five species that had not been previously identified as fry predators. Yellow perch and rock bass dominated the predator community at two study sites (83% of total catch, N=1179, 77% of all fry predators, N=57). Predator presence and fry consumption was almost entirely nocturnal. There was a linear aggregational response in predator CPUE (fish/hr) to increasing fry relative abundance (p<0.033) but confirmed predators did not exhibit a functional response. There was evidence of a threshold of fry relative abundance at 1 fry/trap/day for the onset and conclusion of fry predation. Temperature was a driving factor in the timing of fry emergence and predator abundance, allowing us to predict the relative impact of predators based on temperature scenarios. Only 5% of the potential predators consumed fry. We used empirical probabilities of consumption to model loss of fry due to predation. This consumption model revealed that predator abundances would have to be extremely high for predation to significantly reduce the population of fry. However, given the relatively high species richness of predators observed at the shallow water study sites, lake trout fry survival is likely to be higher at deep, offshore reefs. These results support the recent shift in restoration efforts to focus on deep reefs.

Diante da importância das culturas do milho, soja e cana-de-açúcar no cenário agrícola brasileiro, sendo grandes geradores de divisas, a maior produtividade dessas plantas é ideal para a economia. Tal produtividade, no entanto, é comumente afetada por insetos praga, como é o caso de Spodoptera frugiperda para o milho, Anticarsia gemmatalis para a soja e Diatraea saccharalis na cana de açúcar. Na modernidade, alternativas de controle para esses insetos, como o controle biológico tem sido buscadas, e por meio do presente estudo buscou-se avaliar a preferência de Euborellia annulipes e Harmonia axyridis por essas três pragas. Objetivou-se ainda verificar a ocorrência de canibalismo e predação intraguilda entre os predadores, avaliando também taxas de consumo da presa pelos predadores em diferentes estágios de desenvolvimento. A ocorrência de competição entre eles com relação à presa também foi verificada, a fim de avaliar o potencial de uso desses predadores no controle biológico aplicado. Os estudos foram laboratoriais e permitiram detectar que ambas as espécies são potenciais predadores para as pragas testadas. Não foram observadas claras preferências por presas, apesar de diferentes taxas predatórias terem sido encontradas para cada uma das presas. / Given the importance of corn, soybean and sugarcane crops in Brazilian agriculture as big exchange generators, greater plant productivity of these plants is ideal to national economy. Pest insects, such as Spodoptera frugiperda in corn, Anticarsia gemmatalis in soybean and Diatraea saccharalis in sugarcane commonly affect such productivity. Nowadays, alternative control techniques for these insects, such as biological control, have been sought after, and through the current work, it was aimed to evaluate the preference of Euborellia annulipes and Harmonia axyridis for these three pests. It was also an objective to verify the occurrence of cannibalism and intraguild predation among predators, evaluating consumption rates of the prey insects by the predators in different development stages as well. The occurrence of competition between them in relation to their prey was also verified, to evaluate these predators\'s potential use in applied biological control. These studies were conducted in a lab setting, and allowed detecting that both species are potential predators for the tested pests. No distinct preferences by prey were observed, albeit the existence of differing predation rates being found for each prey.

Patients with dementia, especially Alzheimer’s disease and particularly those in early stages, are susceptible to become victims of predators: Their agnosia (see Case 1) prevents them from detecting and accurately interpreting subtle signals that otherwise would have alerted them that they are about to fall for a scam. Furthermore, their judgment is impaired very early in the disease process, often before other symptoms manifest themselves and usually before a diagnosis is made. Patients with early stages of dementia are therefore prime targets for unscrupulous predators, and it behooves caregivers and health care professionals to ensure the integrity of these patients. In this case study, we discuss how a man with mild Alzheimer’s disease was about to fall for a scam were it not for his vigilant wife. We discuss what went wrong in the patient/caregiver interaction and how the catastrophic ending could have been avoided or averted.

The occurrence of child sex abuse in the United States has long been considered a problem of paramount importance (e.g. Durkin, 2002; Howitt, 2008; Jenkins, 1998). Historically, the primary assumption was that the sexual solicitation of children occurred face-to-face. However, with the advent of communication technologies, people began to realize the internet's role in child solicitation. In an effort to combat this mode of child luring, a concerned citizen created P-J, an organization that seeks to identify and incriminate online predators (OPs). Members of this organization (PJMs) wait in online spaces for OPs to approach them. Then PJMs communicate as if they are minors to gather incriminating evidence against the OPs. PJMs and OPs have incompatible goals for their interactions. OPs' aim to foster a sexual relationship with a minor without being punished for it. PJMs' aim to gather enough evidence against OPs to convict them and prevent the future luring of children. To accomplish these goals, PJMs and OPs communicate with each other and face unique dilemmas in doing so. The current dissertation employs Action-Implicative Discourse Analysis (AIDA; Tracy, 1995), a theory-method package that helps identify strategies used by interactants to address their institutionally based communicative dilemmas, to answer the research questions: 1) How do PJMs communicatively address their dilemma of encouraging online predators to pursue sexual contact without entrapping or making OPs suspicious, and 2) How do OPs communicatively address their dilemma of seducing their targets without getting caught or scaring off the presumed minor? By doing so, the project expands extant knowledge of grooming and computer-mediated self-presentation. It also extends the use of AIDA to contexts beyond organizations and formal institutions. Through the sampling and constant comparison procedure of 40 PJM-OP instant messenger transcripts provided by the organization's website, the researcher identified four overarching categories of strategies that PJMs used to manage their dilemma: Target Presentation, OP Safety, Sexual/Relational Contribution Management, and Bust Facilitation. The researcher also identified five overarching categories of strategies for OPs: Identity Establishment, Relationship Management, Safety Precautions, Sexual Communication Engagement, and Meet Facilitation. Within these categories are many strategies PJMs and OPs utilized in an effort to address their dilemmas of attaining their goals while avoiding risks. By identifying the aforementioned strategies, the researcher satisfied her primary goal of recognizing and understanding how PJMs and OPs attempt to reach their respective goals while avoiding risks. In addition to fulfilling this primary goal, the results of this project entail implications for several different lines of research. Specifically, the results of this dissertation extend research on traditional and online grooming, self-presentation online, and AIDA. The results also provide practical implications concerning what adolescents should be wary of when communicating with unknown others online. Additionally, the study has the capacity to help PJMs become more aware of OPs' strategies as well as their own. This awareness could help PJMs more efficiently train new PJMs and gain a deeper understanding of their interactions.

Predation by olfactory meso-predators has a large impact on avian nest success, particularly for ground-nesting waterfowl. Olfactory predators rely on odors to locate their prey. Weather conditions (e.g. wind speed, humidity, and temperature), vegetation, and landscape features affect the dissipation rate of odors and could affect the foraging efficiency of olfactory predators. I conducted 2 studies to determine if weather and landscape impact predator foraging ability and behavior: a predator survey study and an artificial nest study. The objective of the predator survey was to investigate how landscape and weather conditions interact to influence the distribution of olfactory meso-predators [e.g. red foxes (Vulpes vulpes), skunks (Mephitis mephitis), and raccoons (Procyon lotor)] in their nightly foraging on the dike. Specifically, I examined how wind speed, wind orientation, temperature, and humidity affect the distribution, number, and species of olfactory meso-predators foraging on the Arthur V. Watkins Dike at Willard Bay State Park and Reservoir. The objective of the artificial nest study was to determine if weather, vegetation, or nest location relative to a large-scale surface feature have an effect on survival of artificial ground-nests in an area dominated by olfactory meso-predators. Artificial nests were placed on the dike throughout the summer of 2009. Spotlighting surveys for predators were conducted from August 2008 to August 2009. I found that section of the dike, time since study initiation, terrain type on the dike, wind speed, and vegetation height during daylight hours affected nest survival. The results indicated that predators formed olfactory search images in that nest survival decreased over the summer, while predator populations remained constant. I observed foxes, skunks, and raccoons while spotlighting for predators. After accounting for time, wind speed and direction were significant predictors of predators' nightly foraging activity with most predators observed when wind speeds were 2 to 4 m/s and winds were blowing from the northwest. Overall the model accounted for 75% of the nightly variation in predator numbers. Additionally, wind speed and direction impacted where predators were foraging. There were interspecific differences among predators in their responses to wind speed with raccoons being observed more than skunks and foxes when the wind was calm and blowing from the south. The results of the spotlighting data indicate that wind speed and direction have a strong effect on foraging activity. Overall, I concluded that wind speed affects predator foraging ability and behavior.

Greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) numbers have declined throughout the western US and are considered a species of concern in most of the eleven states that are within their range. Sage-grouse habitats have been reduced by approximately 44% since European settlement of the Western United States began (Miller et al. 2011). Loss of habitat has contributed to an average decline of sage-grouse populations by 33% across the range (Connelly and Braun 1997). To expand our knowledge of this species, I monitored 16 radio-collared sage-grouse captured from four leks in Hamlin Valley, Utah, USA in 2011 and 2012 to determine habitat use. The Hamlin Valley population was primarily one-stage migratory but non-migratory behaviors were also observed. Birds from at least one of the leks used seasonal habitats in neighboring Nevada. Sage-grouse evolved in habitats where infrastructure (e.g. vertical structures) was not common. Introduction of infrastructure, such as fences in their habitat, can cause direct mortality via collision but may also indirectly influence productivity by increasing artificial perches for avian predators (e.g. golden eagles (Aquila chrysaetos) , red-tailed hawks (Buteo jamaicensis), and common ravens (Corvus corax). This research focused on collision rates and increased potential for avian predation on two small populations on the southern portion of the range of current occupied sage-grouse habitat in southwestern vi Utah. During 2011-2012, over 450 km of fences were surveyed for signs of collision and use by avian predators during all seasons (breeding, fall migration, and winter). No sage-grouse collisions were observed suggesting that management for sage-grouse in small populations may be better focused on improving habitat and reducing other causes of mortality which may be more prevalent. Fence post width (i.e. the perching surface) was the best predictor of use as perch by avian predators. Additionally, areas farther from other natural perches, with a low density of surrounding vegetation, and fences constructed along defined habitat edges were used by avian predators more frequently. Results of this study suggest that managers should construct fences with small widths to deter avian predators and care should be taken to maintain contiguous vegetation on either side of the posts while maintaining low shrub density.

Selecting a nest site is an important decision for waterfowl. Because most nest failure is due to depredation, the primary selective pressure in choosing a nest site should be to reduce depredation risk. This task is difficult because predators use differing tactics to locate nests, such as olfactory or visual cues. I investigated several components of waterfowl nest-site selection and success on sites with shelterbelts (planted tree-rows) in North Dakota, during the 2006 and 2007 nesting seasons. I found that meteorological conditions impacted nest depredation; artificial nests were more likely to be depredated when either temperature or dew point was high. These meteorological conditions should improve foraging efficiency for olfactory predators by increasing odor concentration. Waterfowl selected nesting sites with greater visual concealment than random locations (lateral concealment). However, the only difference found between successful and depredated nests was lateral dispersion, an olfactory concealment characteristic. Nest density was higher in areas without shelterbelts than in areas near shelterbelts. Nest success for waterfowl decreased as shelterbelt height increased. Other shelterbelt characteristics, like porosity and orientation, did not affect nest success or nest density. Given that nest predators differ in foraging habitat, temporal patterns of activity, and searching modalities, nest site characteristics that conceal the nest from 1 predator species may increase its vulnerability to another predator. For instance, risk due to olfactory predators should be reduced near shelterbelts because locating nests would be more difficult as turbulence is generated by the shelterbelts. Concomitantly, shelterbelts could also increase the presence of visual predators, by providing nesting sites and vantage points. In my study, any benefits shelterbelts provide in reducing nest depredation by olfactory predators may have been offset by increasing nest depredation from visual predators. Hence nesting near shelterbelts was neither a liability nor a benefit to ducks.

Freshwater ecosystem degradation in the Amazon and Orinoco river basins is increasing due to rising human population numbers, and large water development projects. Therefore, monitoring ecosystem condition in these rivers of high biodiversity is of global conservation importance. This dissertation evaluated the potential of using river dolphins as indicators of ecosystem condition in large tropical rivers of South America. First, population estimates of river dolphins were obtained by line-strip transect surveys and mark-recapture methods on photo-identifications. Using this information, I identified critical habitat, hotspots, and areas of concern for river dolphins, as well as the relationship between dolphin density and group size estimates with ecological features. Second, I evaluated the relationship between dolphin estimates and human stressors. Higher densities of dolphins occurred in rivers with low indices of overall freshwater degradation, such as rivers with high water quality and the lowest human population numbers. Thus, dolphin density estimates seem to be good indicators of freshwater ecosystem degradation in the Amazon and Orinoco basins. These top predators not only are indicator species, but also have the potential to act as flagship and sentinel species, indicating freshwater ecosystem degradation and stimulating conservation action. This dissertation highlights the large changes in the Amazon and Orinoco that are approaching fast. Indicator, flagship and sentinel species can become science-based conservation tools not to only document freshwater ecosystem degradation, but to raise awareness about broader implications of human stressors on biodiversity and river systems.