The release of biological control agents into the environment is inherently risky: assessment of those risks through on-going, post-release monitoring is very important. Herbivores have the potential to inflict multiple impacts on a host plant’s performance and reproduction. Previous research demonstrates that the effects of herbivory on plants include changes to plant architecture, biomass allocation, flowering time and reproductive success, to list a few. Moreover, when herbivory significantly impacts the population ecology of a dominant community member, other species can be indirectly affected, ultimately influencing plant community ecology. Here I describe an investigation into the impacts of two introduced herbivorous biological control agents: the leaf beetle Galerucella calmariensis (Coleoptera: Chrysomelidae), and the flower-feeding weevil, Nanophyes marmoratus (Coleoptera: Brentidae) on several characteristics of the host plant species, invasive purple loosestrife (Lythrum salicaria), and its surrounding community. I collected data on 18 invaded communities from around eastern Ontario, including information on feeding damage and the density of each species of biological control, along with data on purple loosestrife’s height and biomass, inflorescence length, inflorescence number and fruit production. The history of each site’s colonization by Galerucella was also considered. I discovered that the density of both Galerucella and Nanophyes at a site was negatively associated with Lythrum fruit production. However, herbivore density was not significantly associated with Lythrum biomass, height or the species richness of the surrounding plant community. This study, conducted 20 years after the initial Ontario release of Galerucella, demonstrates that although vegetative traits of Lythrum do not appear to be significantly impacted by the presence of Galerucella or Nanophyes, reproductive traits are. Twenty years is likely too short a time period to adequately assess the impacts of the release on community species richness, although my data indicate that communities with smaller Lythrum plants tend to have higher species richness. This study covered a small geographical area and data collection was conducted for a single season only; adding additional years and/ or sites is recommended.

Invasive species have caused billions of dollars in damages to their introduced environment through direct effects on wildlife and by altering their introduced habitats. For a species to be considered invasive, it must successfully navigate the stages of invasion: it must be introduced, become established, spread, and have a quantifiable impact on its introduced environment. The numbers of introductions and individuals released affects the genetic diversity of nonnative populations which, in turn, can affect their invasion success. The Mayan Cichlid (Cichlasoma urophthalmus) is endemic to the Atlantic coast of Mexico and Central America. It was first detected in the United States in 1983 in Everglades National Park. Since then, it has spread across more than 70,000 hectares throughout southern and central Florida. I have established the Mayan Cichlid to be a successful invader in Florida by quantifying per capita negative impacts of Mayan Cichlids on densities of Sheepshead Minnow (Cyprinodon variegatus), Marsh Killifish (Fundulus confluentus), and Eastern Mosquitofish (Gambusia holbrooki) over a 15-year period. I also analyzed the role of genetics in the invasion success of the Mayan Cichlid. I used a mitochondrial gene, cytochrome b, and 17 microsatellite loci to identify the sources for the Mayan Cichlid introduction into Florida. Cytochrome b data supported an introduction from Guatemala; microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. I also found evidence of cytonuclear disequilibrium together with low genetic diversity within the Florida population which indicate a population bottleneck and admixture between two distinct lineages upon introduction, followed by rapid spread resulting in a panmictic population genetically distinct from the native range populations. I found much less genetic structure and a weaker correlation between genetic diversity and geographic distance within Florida compared with Mexico and Central America. Low number of effective alleles, heterozygosities, and FST values and the genetic similarity of Florida sites also indicate an admixed population or one that has rapidly expanded from a small initial group.

This work explores the fragility of the Great Lakes and the environmental degradation we have caused. My main focus revolves around what the EPA considers to be the Great Lakes Areas of Concern (AOCs). This list contains 27 rivers that flow into the Great Lakes, most of which are or have been areas of industrial and chemical pollution. Through installations involving photography, ceramics, and video, I hope to reveal the issues facing the Great Lakes and explore how people can help.

ABSTRACT UNDERSTORY PLANT COMMUNITY STRUCTURE IN FORESTS INVADED BY GARLIC MUSTARD (ALLIARIA PETIOLATA) MAY 2016 JASON ALLEN AYLWARD, B.S., PAUL SMITH’S COLLEGE M.S. UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Kristina Stinson Plant invasions represent a significant threat to the structure and function of natural ecosystems. Garlic mustard (Alliaria petiolata) has been identified as a threat to native communities mostly through small-scale studies and focused experiments. In this in situ observational study I examined the effects of garlic mustard invasion on species composition across multiple sites by comparing plant diversity and composition in invaded and adjacent non-invaded communities. Mean Shannon diversity was higher in invaded compared to non-invaded plots and invasion was associated with greater densities of invasive species such as burning bush (Euonymus alatus), and greater celandine (Chelidonium majus). In ordination space, the sites grouped more closely by geographic region than by invasion status, suggesting that regional environmental variation is important for community structure. My findings indicate that garlic mustard invasion is associated with other invasive plants, and that the understory plant community varies considerably across the region regardless of invasion status. Overall we show that community structure in garlic mustard invaded forest understories is not consistent across the landscape.

<div>Wetland-dwelling amphibians are of conservation interest for numerous reasons. They serve as biological indicators of water quality during their fully aquatic larval phase, and as carnivores that prey extensively on both terrestrial and aquatic invertebrates. These amphibians are an important link between terrestrial and aquatic food webs, and their wellbeing is an important factor when considering ecosystem health. Amphibians are facing global declines as their wetland habitats are being lost or degraded by human actions. There are efforts to restore wetland habitats, but it is far from certain which practices encourage amphibian occupancy.</div><div>I investigated which factors are important to the persistence of amphibians in restored and naturally formed wetlands to see if restored wetlands can accommodate similar species assemblages. Amphibians were surveyed over two years in a collection of 18 wetlands in Steuben and DeKalb counties, IN owned by The Nature Conservancy. Ambystomatid salamanders were surveyed using plastic minnow traps in springtime, and frogs were surveyed using call surveys in spring and summer. I used linear models to compare wetland plant dominance, wetland hydroperiod, restoration status, distance to nearest mature forest, adjacent forest age and basal area, and inter-wetland distance to amphibian species richness.</div><div>The species richness of Ambystoma salamanders was positively associated with larger wetlands, higher forest basal area, and central mudminnow presence; and negatively associated with older forests, distance to mature forests, and the presence of sunfishes. Ambystoma salamanders besides A. tigrinum were associated with ephemeral hydrology, naturally-formed wetlands, and a greater number of wetlands within one km; and negatively correlated with older forests.</div><div>Frog species richness was positively associated with larger wetland size, and negatively associated with seasonal wetlands, naturally-formed wetlands, distance to nearest mature forests, naturally formed wetlands, treatment for invasive plants, and number of other wetlands within 500m. Total amphibian species richness models did not perform well, but showed a preference for semi-permanent wetlands, smaller distance to mature forests, greater forest basal area, and greater distance between wetlands; and a preference against Scrub Shrub/Forest wetlands. Hylid frogs were negatively correlated with naturally formed wetlands. Ranid frogs were associated semi-permanent wetlands and negatively correlated with the number of other wetlands within 500 m.</div><div>Ambystomatid salamanders were found in restored wetlands, semi-permanent wetlands, and in wetlands containing central mudminnows. Frogs may dislike the disturbance from removing invasive grasses. Managers should factor the disparate habitat requirements of amphibian taxa into their plans for creating and managing restoration projects. Different amphibian groups appear to differ greatly in their habitat requirements, and diverse wetlands may enhance the species richness of an area. Skillfully restored wetlands appear to serve similar functions to original, naturally formed ones.</div>

Three wetland restoration methods: seeding, seeding + hay mulch, and seeding + hay mulch + vegetation plugs were compared via the plant community within a formerly cropped wetland in southeastern North Dakota. Arrangement of plugs were also compared to assess the success of native species establishment. Mean relative cover for native species and introduced species were recorded and analyzed to compare the restoration methods and plug arrangement. Three herbicide treatments were studied on upland prairie sites with and without prescribed burning to test effects on leafy spurge (Euphorbia esula) control and seeded native establishment. There is no difference native species richness between the restoration methods six years post restoration, and no difference in plant cover in the different arrangement of plugs. Quinclorac significantly reduced leafy spurge cover; however, glyphosate treatments had higher cover of seeded native species.

Without an adequate understanding of complex interactions between native and non-native species, management of invasive species can result in unforeseen detrimental impacts. I used both field and laboratory experiments to study reciprocal species interactions between the endangered Mohave tui chub (Siphateles bicolor mohavensis) and invasive western mosquitofish (Gambusia affinis). I also examined the impacts of both fish species on the aquatic invertebrate communities in desert springs. I demonstrate a case of intraguild predation (IGP) as a mechanism facilitating co-persistence of the endangered Mohave tui chub with invasive mosquitofish using field mesocosm experiments. In this case of IGP, adult tui chub prey on adult and juvenile mosquitofish, while adult mosquitofish prey on tui chub eggs and/or larvae. I conducted laboratory predation trials to assess if IGP was size-structured due to predator gape-limitation. I explored sex specific differences in gape-size limitation in mosquitofish, because mosquitofish are sexually dimorphic. Larval tui chubs had lower survival in the presence of female mosquitofish than in the presence of males. Reciprocally, male mosquitofish had lower survival than the females in the presence of Mohave tui chub. These results combined with vulnerability modeling supported that IGP in this system is size structured based on gape-size limitation. These results collectively suggest size-structured IGP may facilitate the co-persistence of these two fish species. My findings also suggest that mosquitofish may not be a limiting factor for the persistence of the endangered Mohave tui chub. Further, habitats currently harboring mosquitofish were considered as future refuge habitats for Mohave tui chub, a management option previously un-available. In addition to such reciprocal interactions between fish species, recently established fish populations may impact unique invertebrate communities. Mesocosm experiments with sympatric and allopatric populations of tui chub and mosquitofish showed negative impacts of both fish species on changes of invertebrate community structure. Specifically, fish caused population declines and, in some cases, extirpations of various invertebrate taxa. These results suggest important conservation implications of invasive fish as well as protected fish transplants into fishless desert springs. Overall my research emphasizes the complexity of ecological interactions between native and non-native fish species in desert aquatic systems.

Le frelon Vespa velutina, est une espèce invasive introduite en France il y a une dizaine d’années. Cet Hyménoptère social chasse de nombreux insectes, et plus particulièrement des abeilles, exerçant une forte pression de prédation sur l’entomofaune. Son établissement en Europe est donc susceptible d’avoir un impact néfaste sur les activités humaines et sur la biodiversité locale. L’olfaction joue un rôle central dans la biologie du frelon, que ce soit pour la communication intraspécifique (phéromones) ou la recherche de nourriture. Pour limiter l’impact de V. velutina, une stratégie prometteuse serait d’interférer avec son comportement olfactif. Nous avons donc cherché à acquérir une meilleure connaissance du système olfactif des frelons ainsi que des signaux chimiques impliqués dans leur comportement de prédation. Nous avons tout d’abord décrit et comparé l’organisation du système olfactif des différentes castes d’une colonie de frelons. Le premier centre olfactif du cerveau, le lobe antennaire, est constitué d’unités morphologiques et fonctionelles, les glomérules. Nous avons démontré l’existence de glomérules hypertrophiées (macroglomérules), potentiellement spécialisées dans la détection des phéromones sexuelles, chez les mâles. Nous avons également observé des similarités neuroanatomiques frappantes dans l’organisation du lobe antennaire chez des Hyménoptères de familles différentes (fourmis, abeilles, frelons), permettant de reconstruire une partie de l’histoire évolutive de cette structure, au sein de cet ordre. En particulier, nous avons démontré l’homologie d’un groupe de glomérules impliqué dans le traitement des hydrocarbures cuticulaires, signaux de reconnaissance intraspécifique, chez les frelons et les fourmis. Ce système a pu représenter une préadaptation pour l’apparition de comportements sociaux dans ces familles. De plus, nos résultats ont montré que le nombre de glomérules dans ce système varie fortement chez différentes espèces de frelons, probablement en relation avec les différents niveaux de sympatrie dans lesquels vivent ces espèces. Le lobe antennaire des frelons présente ainsi des adaptations concernant aussi bien le nombre de glomérules que leurs volumes respectifs. Enfin, nous avons effectué des essais comportementaux pour déterminer quels composés odorants sont impliqués dans l’attraction de V. velutina envers les ruches d’abeilles domestiques. Nos résultats suggèrent que les ouvrières de frelon sont sélectivement attirées par des odorants indiquant la présence de ruches, dont des phéromones d’abeille. Ces résultats permettent d’envisager le développement de stratégies de piégeage utilisant des appâts olfactifs spécifiques. / The hornet Vespa velutina is an invasive species introduced from China to France about 10 years ago. This social hymenoptera preys on numerous insects species, but predominantly from honeybee colonies, hence exerting a stong predation pressure on insect fauna. Its etablishment to Europe can have strong detrimental effects on human activities and local biodiversity. Olfaction plays a central role in the biology and behavior of hornets, for both intraspecific communication or food search. To limit the impact of V. Velutina, a promising strategy would be to interfere with its olfactory behaviors. We thus aimed to acquire a better knowledge on the olfactory system of hornets and on the chemical signals involved in their predatory behavior. We first described and compared the organization of the olfactory system of the different castes of hornets. The first olfactory processing center, the antennal lobe, consists of morphological and functional units, the glomeruli. We have demonstrated the existence of enlarged glomeruli (macroglomeruli), potentially specialized in the detection of sex pheromones in males. We also observed striking neuroanatomical similarities in the antennal lobe organization of different Hymenoptera families (ants, bees, hornets) allowing to retrace part of the evolutionary history of this structure within that insect order. In particular, we demonstrated the homology of a glomerular cluster involved in the processing of cuticular hydrocarbons (intraspecific recognition signals) among hornets and ants. This systsem could be a preadaptation for the emergence of social behaviors in these families. In addition, our results showed that the number of glomeruli within this system varies across hornet species, probably due to the different sympatry levels these species experience. The hornet antennal lobe presents adaptations both in the number and the volume of glomeruli. Finally, we performed behavioral tests to identify odor compounds involved in the attraction of V. Velutina towards bee hives. Our results suggest that workers are selectively attracted to olfactory cues indicating the presence of hives, including some honeybee pheromones. These results allow considering the development of trapping strategies using specific baits.

No description available.

Originally endemic to South America, the nine-banded armadillo (Dasypus novemcinctus) has recently expanded its range northward to Illinois. With this range expansion comes concern from both wildlife managers and the general public regarding potential incoming pathogens and unknown impacts on native wildlife. My research, conducted during 2018-2020 in southern Illinois, addressed the following 3 objectives intended to provide information regarding this novel species: (1) test for the presence of Trypanosoma cruzi and Mycobacterium leprae, (2) model the potential distribution of armadillos, and (3) attempt several different armadillo capture methods. For Objective 1, I tested roadkilled specimens for T. cruzi and M. leprae, 2 pathogens known to infect humans, using PCR and ELISA, respectively. All 81 samples tested for T. cruzi and all 25 samples tested for M. leprae were negative. The latter case is consistent with the enemy release hypothesis, suggesting armadillos have evaded parasites present in their native environment due to geographical distance. The absence of T. cruzi in the sampled individuals implies dispersing individuals are more robust than those at the center of their range. For Objective 2, I used MAXENT to model potential armadillo distribution in 51 counties in southern Illinois using 39 presence locations. Modeling identified low-intensity development to be the most important predictor of armadillo presence. For Objective 3, I attempted to capture armadillos using spotlighting on roads, staking out burrows, unbaited single-door cage traps, and unbaited double-door cage traps. Based on trap nights per capture, I found the use of double-door cage traps to be the most efficient method. My study will aid in managing colonizing armadillo populations by presenting information regarding dynamics of disease transmission, predicting areas of armadillo presence, and capture methods.