I studied the autecology, community ecology, and genetics of an endangered butterfly, the maritime ringlet (Coenonympha nipisiquit McDunnough), that inhabits a limited number of salt marshes in northern New Brunswick and in the Gaspé Peninsula of Québec. I studied the survival rate of first- and second-instar larvae in various microhabitats in a salt marsh at Daly Point Natural Reserve, Bathurst, New Brunswick. I found they survived significantly better in microhabitats dominated by Spartina patens (Aiton) Muhl. at an intermediate elevation. I investigated the tolerance of the maritime ringlet larvae to tidal submergence and compared their performance to a closely related taxon, the inornate ringlet (C. tullia inornata Edwards). The experiments revealed that the maritime ringlet possesses unique adaptations to tidal submergence. I examined the flight and oviposition behaviors of adult females in response to microhabitat. I found that they did not discriminate between microhabitats based upon the likelihood of larval survival as long as S. patens or other potential hosts were abundant. I explored the correlation between predator species richness and abundance with the larval survival rate in microhabitats. I found that predator abundance and species richness often responded negatively to increasing tidal flooding, suggesting that high larval mortality at high elevation sites can be caused by high predation pressure. Lastly, I investigated the possibility of genetic introgression between the maritime ringlet and inornate ringlet and reconstructed the phylogeny of the C. tullia-group taxa in North America. The genetic evidence did not support the possibility of large-scale genetic introgression and raised the taxonomic status of the maritime ringlet from a subspecies of holarctic C. tullia to a full species. The phylogenetic analyses suggested that the divergence of the maritime ringlet was much earlier than previously believed. My results will aid in protection and recovery of this endangered species.

The hemlock woolly adelgid, Adelges tsugae, is an invasive insect from Osaka, Japan threatening populations of eastern hemlock, Tsuga canadensis, and Carolina hemlock, Tsuga caroliniana, in the eastern United States. Previous studies of adelgid population dynamics and hemlock response in the early-1990s suggested that once infested, trees were likely to die within 4 to 6 years; widespread eradication of hemlock throughout the region was expected. However, the vast majority of hemlocks in western Massachusetts are still alive and many are not yet infested, despite the adelgid having been present in the state for 17 years. Many examples of individual trees in Massachusetts harboring adelgid for over ten years have been documented. In order to understand this discrepancy, we conducted detailed lifetable studies of the hemlock woolly adelgid at six locations in Connecticut and Massachusetts from 2004-2008. Adelgid density, fecundity, and survival data as well as temperature and precipitation data were examined to document and understand the apparent stability of adelgid populations in the northeast. These data were also used along with climate projection models to predict the range of suitable habitat for adelgid under two scenarios of carbon emissions through the year 2100. In an attempt to regulate adelgid populations, several species of biological control agents have been released, including Laricobius nigrinus Fender (Derodontidae), Sasajiscymnus tsugae Sasaji and McClure (Coccinellidae), and Scymnus ningshanensis Yu and Yao (Coccinellidae). Since few studies have addressed the efficacy of these beetles above the branch level, we conducted an experiment to test their effects on adelgid populations using whole-tree enclosures. These data, in addition to adelgid demography data will be useful in predicting future outbreaks, constructing simulations of adelgid growth and spread, and determining the amount of additional mortality needed from a biological control agent to stabilize adelgid populations.

Elongate hemlock scale (Fiorinia externa) is an invasive species from Japan that was first detected in the United States in 1908 and has established in most states where eastern hemlock (Tsuga canadensis ) occurs. Scale density is much higher in the US (21 to >400 scales per 100 needles) compared to Japan (<1 scale per 100 needles) despite the presence in both regions of the parasitoid Encarsia citrina that has been assumed to be responsible for low densities in Japan. I have found that phenology of the vulnerable scale stage was asynchronous with E. citrina flight throughout the eastern United States. This asynchrony was the result of overlapping life stages and generations of elongate hemlock scale throughout the growing season. This overlap appears to result from delayed senescence of first generation adult females. To investigate the impact of E. citrina on elongate hemlock scale, natural enemy exclusion experiments were conducted. I found that E. citrina exerts some control on elongate hemlock scale, but insufficient to maintain density at levels seen in its native Japan. Existing records of parasitoids of elongate hemlock scale in Japan are limited to the Kyoto area. I sampled the parasitoid community of elongate hemlock scale and other scales on hemlock throughout Japan. Sequence data from two gene loci, 28SD2 and COI, were used to identify the number of unique parasitoid species attacking scales on Japanese hemlocks. This sequence data was also used to identify possible cryptic species within E. citrina in Japan. Twenty-two genetically distinct parasitoids were identified (seven singletons). Eleven (three singletons) of these were from elongate hemlock scale. With the exception of E. citrina, parasitoids tended to be host species specific. No evidence of cryptic species within E. citrina was found. The parasitoids identified dramatically increase the number of elongate hemlock scale parasitoids previously reported and this study may lead to the identification of several potential biological control agents of elongate hemlock scale for introduction to the United States.

The present research provides the first evidence for specific receptor binding of polyhedra-derived baculovirus (PDV) to host cells and to lepidopteran brush border membrane vesicles (BBMV) and demonstration of entry via a non-endocytotic pathway involving direct membrane fusion. The technique of fluorescence-activated cell sorting (FACS) analysis was employed to investigate the specificity of binding between the PDV phenotype of Lymantria dispar multicapsid nuclear polyhedrosis virus (LdMNPV) and host membranes. Fluorescein-labeled PDV was found to bind in a saturable manner to the gypsy moth cell line, IPLB-LdEIta, and to L. dispar BBMV. Excess levels of unlabeled PDV were highly efficient in competing with FITC-labeled PDV for limited receptor sites further supporting the specificity of the interaction. Major reductions in virus binding (as high as 70%) after protease treatment of cells indicated that a protein receptor is involved. A fluorescence dequenching assay of membrane fusion with octadecyl rhodamine B (R18)-labeled PDV as used to identify PDV fusion to host cells and BBMV. Fusion of PDV occurred at 27$\sp\circ$C to both target membranes, as well as at 4$\sp\circ$C at approximately 55% of the levels achieved at 27$\sp\circ$C. Virus fusion to BBMV occurred throughout the pH range of 4-11 with dramatically increased fusion levels (3x) under the alkaline conditions normal for lepidopteran larval midguts. Treatment of tissue cells with chloroquine, a lysosomotropic agent, did not significantly affect PDV fusion to cells or infectivity in tissue culture. To begin to characterize viral and host proteins involved in establishment of infection, monoclonal antibodies (MAbs) were produced against LdMNPV PDV as well as L. dispar BBMV. While no PDV-neutralizing MAbs were isolated, anti-BBMV MAbs were identified which appeared to alter either PDV fusion or infectivity. To determine whether LdMNPV occlusion bodies (OBs) may contain a soluble enhancing factor similar to that identified for several granulosis viruses, soluble LdMNPV OB proteins were tested in larval bioassays for enhancement of PDV infectivity and assayed for the ability to degrade L. dispar peritrophic membrane proteins. Soluble LdMNPV OB proteins were unable to enhance LdMNPV infectivity and did not degrade larval PM proteins.

"Zombie ants," Ophiocordyceps fungal infected Camponotus floridanus, are a valuable model to study how parasites can change host behavior to benefit their own transmission. Recent findings using molecular approaches reveal indirect strategies, such as effector secretion, employed by the fungus for successful manipulation. Yet the direct interactions between the host tissues and fungal cells remain largely unknown. As such, we used micro-computed tomography to visualize the internal morphology of ants throughout Ophiocordyceps infection. Moreover, recent work on microbiomes is providing increasing data on the importance of gut microbiota in organism functioning. Digestion and nutrient absorption, reproduction, and even host immune defense are all impacted by microbiota. Therefore, we characterized both the bacterial and fungal gut microbiomes of Ophiocordyceps-infected ants to investigate if the host microbiome changes during infection. For both aims, we contrasted the results for Ophiocordyceps infections against Beauveria infections to learn 1) if the results are specifically related to behavioral manipulation or more general hallmarks of fungal infections, and 2) if Ophiocordyceps and Beauveria can indeed be classified as a hemi-biotroph and necrotroph, respectively, because they interact with their host differently. Our findings provide initial evidence of potentially different infection strategies employed by the fungal entomopathogens we investigated.

Urbanisation and associated anthropogenic activity release large quantities of metallic elements and metalloids into the environment. Due to their toxicity, environmental persistence and bioaccumulative nature, these chemical pollutants threaten wildlife and human health. As urbanisation increases and top predators are forced to utilise more urban spaces, they will likely be exposed to more toxic heavy metals and metalloids. As secondary and tertiary consumers, terrestrial carnivores may be at increased risk of metal exposure through biomagnification effects. Relatively little is known about this emerging threat to terrestrial carnivores persisting in human-transformed landscapes, especially in the Global South. To better understand the extent of this issue, I quantified the level of metallic element and metalloid exposure in a sentinel top predator, the caracal (Caracal caracal), inhabiting the rapidly-urbanising, primarily coastal metropole of the Greater City of Cape Town, South Africa. Whole blood samples (n = 67) from GPS-collared (n = 25) and opportunistically sampled (n = 31) individuals were collected. Using Redundancy Analysis (RDA) and mixed-effect models, I explored the relative influence of caracal demography, landscape use, and diet on levels of individual exposure to 11 metallic elements and metalloids: Aluminium (Al), Arsenic (As), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Mercury (Hg), Manganese (Mn), Lead (Pb), Selenium (Se), and Zinc (Zn). Mean metal concentrations (including Al, Cd, Co, Cu, Hg, Mn, Pb, Se and Zn) were generally found to be below toxic thresholds, however, As and Cr are present at potentially sublethal levels in certain individuals. The results suggest that increased use of human-transformed landscapes in home ranges (particularly urban areas, roads, and vineyards) was significantly associated with increased caracal exposure to Al (P < 0.05), Co (P = 0.05) and Pb (P = 0.07). Home ranges closer to the coast (RDA, P < 0.05) and feeding within aquatic food webs (marine and wetland-adapted prey) were associated with higher blood levels of Hg (P < 0.05), Se (P < 0.01) and As (P < 0.05). Further, increased predation on seabirds and aquatic birds likely facilitates the transfer of metals from aquatic to terrestrial food webs. Overall, these findings highlight the importance of urbanisation and anthropogenic activity as major environmental sources of metal exposure in terrestrial wildlife, including more natural areas through long-distance transport of pollutants. Further, they contribute towards a growing global evidence base suggesting cities act as ecological traps for wildlife, threatening their long-term health and persistence in these landscapes. Therefore, it is crucial that cities work to reduce the large quantities of chemical pollutants released into their surrounding environment. In Cape Town, this effort could be focused on the urban edge, waste management, water treatments, roads and agricultural areas. Future research into a possible ecological trap for urban-adapted carnivores should focus on assessing metal exposure at different trophic levels and investigating the potential physiological responses of exposure in species. I argue that the caracal is a valuable sentinel for assessing metal exposure and should be used in tandem with other small and mediumsized carnivores and aquatic bird species in local and national pollutant monitoring programmes to mitigate further exposure and promote carnivore conservation in human landscapes. A charismatic species, with a well-established local platform of research and science communication, the caracal is centrally positioned to help promote greater public awareness and engagement in issues concerning environmental pollutant contamination and monitoring.

Secondary metabolites are organic compounds produced by plants that are not essential in growth, development, or reproduction. While they are not strictly necessary to complete the plant life cycle, secondary metabolites play key roles in functions like defense against herbivory and the moderation of symbiotic relationships. Terpenes are a major class of secondary metabolites present in all plants, and this class is hypothesized to have diversified in response to specific plant-herbivore interactions. These complex interactions are further complicated by changes in abiotic conditions experienced seasonally. Herbivory is a major biotic interaction that plays out across broad temporal and spatial scales that vary dramatically in temperature regimes, both due to climate variation across geographic locations as well as the effect of seasonality. In addition, there is an emerging understanding that global climate change will continue to alter the temperature regimes of nearly every habitat on Earth over the coming centuries.Regardless of source, variating in temperature may influence herbivory, in particular via changes in the efficacy and impacts of plant defense chemistry. This study aims to characterize temperature-driven variation in the toxicological effects of several structural classes of terpenes in the model herbivore Vanessa cardui, the painted lady butterfly. We observed and increase in terpene toxicity at higher temperatures and an increase in development time as terpene concentration increased. Results obtained from this study yield insights into possible causes of seasonal variation in plant terpene production as well as inform effects of rising global temperatures on plant-insect interactions.

No description available.

No description available.

No description available.