Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 77-79). Also available via the Internet.

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The National Ecological Observatory Network (NEON) will monitor ground beetle populations across a network of broadly distributed sites because beetles are prevalent in food webs, are sensitive to abiotic factors, and have an established role as indicator species of habitat and climatic shifts. We describe the design of ground beetle population sampling in the context of NEON's long-term, continentalscale monitoring program, emphasizing the sampling design, priorities, and collection methods. Freely available NEON ground beetle data and associated field and laboratory samples will increase scientific understanding of how biological communities are responding to land-use and climate change.

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The objective was to analyze the effects of logging and prescribed burning on carabid beetles (Coleoptera: Carabidae) at a jack pine stand and white spruce plantations in order to assess short-term impacts of these forestry practices on the diversity of this beetle group. In addition, soil scarification was also included at the jack pine stand. Based on previous reports on forest disturbance influences on carabids, it is hypothesized that short-term effects of studied forestry practices do not reduce carabids' diversity. Four carabid assemblage characteristics were compared: (a) number of catches; (b) dry mass; (c) species richness; and, (d) diversity index. Species responses and dry mass distributions were also investigated. Treatments either increased or maintained studied variables compared with control sites. Diversity indices were highest in burnt-over areas. Similar response patterns of species or groups of species were observed in both forest types. The presence of regenerating sites among the natural landscape increased carabid diversity.

Sitona lineatus L. (Coleoptera: Curculionidae) is a pest of Pisum sativum L. (Fabales: Fabaceae) and managing it is a challenge because of its fecundity, migratory behavior and concealed larval habitat. Potential components of an integrated pest management program for S. lineatus were investigated near Lethbridge and Vauxhall, Alberta over three years. Cage studies indicated that larval feeding is more damaging than adult feeding but that larval populations are not dependent on adult weevil density. In open plot experiments, thiamethoxam-treated plants experienced significantly less foliar feeding damage than plants receiving no insecticide treatment but no consistent effects on yield were observed for any plot treatment over six site-years. Rhizobium inoculation had a synergistic interaction with thiamethoxam. Laboratory trials showed that Bembidion quadrimaculatum L. (Coleoptera: Carabidae) consumed S. lineatus eggs. Seed treatment with thiamethoxam and Rhizobium inoculant, and egg predation should be included in an integrated pest management program for S. lineatus. / Plant Science

This thesis deals with the determination of the direct impact of spraying on soil invertebrates by comparing the treated and untreated surfaces by spraying with plant protection products. The experiment took place in crop of winter oilseed rape in the western part of South Bohemia in spring 2012. As bio-indicators were used ground beetles beetles (Carabidae). Trapping was conducted using pitfall traps. In this work we compared the difference in the occurrence of ground beetles in treated and untreated crop of winter oilseed rape and subsequent tree alley. Only 15% of beetles was recorded sprayed areas, 69% in untreated areas and and 16% in the alley. This suggests the direct impact of spraying on non-target organisms. That's followed by a second experiment, which aim was to determine the long-term effects of intensive farming on ground beetle populations in habitats related to reporting rape field. The selected habitats were meadow, pasture, alley, ruderals and riparian vegetation. The results indicated the inportance of the biotops consequent to field as tthe refugium and the center of spreading of groujd beetles to the field where they provide ecosystem service of biological control.

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La flore adventice est à la base des chaînes trophiques dans les agroécosystèmes. Leur diminution dans les parcelles cultivées est une des causes de la baisse de la biodiversité. Par conséquent, des alternatives sont étudiées pour diminuer l’utilisation des herbicides dans le cadre du plan ECOPHYTO. Par exemple, la gestion de la flore adventice via les consommateurs de graines. En effet, les agroécosystèmes sont des milieux où des espèces granivores ont les capacités de consommer les graines d’adventices. Parmi les vertébrés, nous pouvons y trouver des oiseaux (alouette des champs) ainsi que des micromammifères (mulot). Parmi les invertébrés, les carabes sont identifiés comme principaux granivores dans les agroécosystèmes tempérés. L’objectif général de cette thèse est d’étudier les interactions entre carabes et graines d’adventices afin d’apporter des connaissances sur les interactions interspécifiques et d’identifier les traits physiologiques des espèces influençant la force des interactions entre les espèces. Un protocole a été établi afin de standardiser toutes les expériences et de garder comme variables uniquement l’espèce de graines et celle du carabe. Ensuite, nous avons étudié les interactions entre les graines d’adventices et les carabes selon deux axes de recherche. Le premier a permis de comparer les niveaux de consommation de la communauté de carabes sur une même espèce de graines. Nous avons pu ainsi observer que la masse corporelle des carabes n’était pas en relation avec la variation des niveaux de consommation. Mais le ratio entre la longueur des mandibules et la largeur du labrum (force mandibulaire) a un effet significatif lorsque seules les espèces consommant plus de cinq graines sont prises en compte. Pour le deuxième axe, nous avons mesuré la consommation des carabes sur 42 espèces de graines pour identifier les capacités de consommation et explorer la stratégie d’alimentation selon deux caractéristiques : la masse des graines (taille) et leur concentration lipidique. Les graines de faibles masses avec un taux lipidique élevé sont mangées en plus grand nombre. Enfin, nous avons déterminé les types de réponse fonctionnelle pour évaluer le potentiel de régulation de 4 espèces de carabes sur deux espèces de graines d’adventices. Pour chaque espèce (mâle et femelle) nous avons trouvé une réponse fonctionnelle de type II, sauf pour les femelles de P.rufipes. Cependant nos résultats doivent être interprétés avec précaution car en milieu naturel d’autres facteurs interviennent dans les interactions, telle que la présence de proies alternatives ou d’autres prédateurs. En conclusion, nous montrons que les interactions entre les graines d’adventices et les carabes sont nombreuses et complexes. Les caractéristiques physiologiques intervenant dans les interactions sont très nombreuses et très variables selon les espèces. Des études supplémentaires sont nécessaires pour évaluer l’intérêt agronomique des carabes dans la gestion des adventices. / Weed flora limits crop yields therefore herbicides inputs are important in order to manage weeds. Weeds are at the bottom of the trophic pyramid in agroecosystems, and this explains partly the decrease of biodiversity. Alternatives to manage weeds are studied to reduce negative effect of herbicides on the environment in order to preserve biodiversity. For example, weeds could be managed with granivorous species. Indeed, weed seeds are the origin of the weed community, thus seed consumption could limit weed abundance in cultivated fields. In agroecosystems, several taxa are known to be granivorous such as vertebrates (birds and rodents) and invertebrates (ground beetles). Ground beetles are considered as the main granivorous taxa in agroecosystems and are abundant in temperate agroecosystems. The main goal of this PhD was to study trophic interactions between communities, weed seed and ground beetles, with a prey-predator system in order to estimate the role of ground beetles through their seed consumption in weed seeds management. First, we established a protocol with standardize steps in order to restrain variables to weed seed species at ground beetles’ species. A similar protocol has been adapted to replicate experimentation with the same individuals to measure consumption at different weed seed densities. We then studied interactions between weed seeds and ground beetles with two research axes. We first explored interspecific variation of consumption on the same weed seeds species, Viola arvensis, by ground beetles. Body mass and ratios between mandible length and labrum width had no relation with seed consumption by ground beetles. Thus, other factors were suggested to explain consumption variation such as gut symbionts of ground beetles or preferences for specific weed seed species. Secondly, we measured consumption of 42 weed seed species by four ground beetles to identify abilities in weed seed consumption for these beetles and to explore feeding strategy according to two seed characteristics, seed mass (size) and seed lipid content. Generalism degrees are different according to ground beetles’ species and seem affected by physiological characteristics in both communities. Finally, to assess the potential in weed seed management of ground beetles we determined functional response to four ground beetles on two weed seeds species. We determined type II response for all species (male and female) tested, except for females of P.rufipes. Our results should be interpreted cautiously as, under natural conditions, generalist predators meet many alternatives prey and it could influence functional response type. We showed that there are many complex interactions between weed seed and ground beetles communities, especially due to a wide range of diversity in physiological characteristics in both communities. The potential of ground beetles to regulate seeds must be more precisely explored to evaluate their agronomic interest in weed management.

This thesis investigates a range of genealogical approaches to making quantitative inferences about the spatial and demographic history of populations with application to two insect systems: A local radiation of high alpine ground beetles (Carabidae) in the genus Trechus and major refugial populations of the oak gall parasitoid Cecidostiba fungosa (Pteromalidae). i) Summary statistics, which make explicit use of genealogical information are developed. Using simulations their power to detect a history of population growth is shown to be higher than that of standard measures such as Tajima’s D for single and multilocus data. The improvement arises from the fact that in contrast to pairwise measures, the new statistics are minimally confounded with the topology. ii) A Bayesian method to reconstructing character states is used to infer the Pleistocene history of populations of high alpine Trechus sampled along a singlemountain range frommitochondrial and nuclear data. Despite evidence for some incomplete lineage sorting, a simple model of a series of extreme founder events out of two refugia during or before the last glacial maximum provides a good fit to the data. iii) A large set of exon-primed, intron-spanning (EPIC) loci is developed for Hymenoptera from EST and genomic data. Amplification success is screened on a range of Hymenopteran species associated with two insect-plant interactions: Oak galls and figs. iv) Borrowing model-based approaches developed to quantify species divergence, the new EPIC loci are used to investigate the relationships between three major European refugia in the oak gall parasitoid C. fungosa. These analyses reveal strong support for an eastern origin, effective ancestral population sizes comparable to insect model species and evidence for recent population divergence during the last interglacial. The results also suggest that there is significant information in minimal samples provided a large number of loci are available. v) Results for the probability of gene tree topologies are derived for a model of divergence with gene flow between three populations. I outline how the asymmetries in the frequency of gene tree topologies may be used to distinguish incomplete lineage sorting from migration and discuss the results in the context of next generation sequence data from D. melanogaster and humans and Neanderthals.