Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. 155-178). Also available via the World Wide Web.

A review of the current understanding of forest tent caterpillar (Malacosoma disstria Hbn.) population dynamics in Ontario suggests that two climatic factors, the temperature at the time of larval feeding and the minimum temperature through the winter, play important roles in determining outbreaks. Comparing the pattern of defoliation to similarly scaled temperature records over 41 years in Ontario shows no relationship between the year to year dynamics of outbreaks and either the temperature through the larval feeding period or the minimum overwintering temperature. A long-term analysis suggests that outbreaks are less severe in those regions with low overwintering temperatures and a patchy distribution of host. This latter finding, combined with an analysis of the synchrony and spread of defoliation, suggests that adult dispersal may play an important role in shaping the dynamics of outbreaks. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (doctoral)--Universität Göttingen, 1999. / Includes bibliographical references (p. 249-277).

2 spread sheets included. Title from title page of PDF (University of Missouri--St. Louis, viewed February 8, 2010). Includes bibliographical references.

The limited availability of land to forestry and the ensuing emphasis on intensive silviculture, developed a renewed interest in soil pests in the establishment of plantations. Ten field trials were planted over three seasons to determine the mortality factors influencing the establishment of commercial eucalypt and black wattle plantations in the Natal Midlands, and simultaneously, to investigate the chemical control of the soil pest component. A complex of indigenous soil pests contribute to an average 22,9 % failure of Acacia mearnsii and Eucalyptus grandis seedlings from reaching full establishment. This pest complex, which includes termites, whitegrubs, cutworms, tipulid larvae, wireworms, millipedes and nematodes, was responsible for an average 12,3 % of the failure of the plantings to establish. In the absence of termites, in shallow humic soils, whitegrubs followed by cutworms were the most frequent and economically important pests. Eucalypts are more susceptible than wattle seedlings to whitegrub damage when planted in marginal sites. Seedlings in the summer rainfall region were most susceptible to whitegrub damage from December to April; and to cutworm damage during the first two months after planting. An average of 398 hectares was annually damaged by whitegrubs and cutworms. The total annual loss in planting costs and the additional costs of blanking over the three year study period were 1,22 and 2,65 million rands respectively. Existing non-chemical control applicable to woodlot forestry is reported. Chemical control as one of the options in the management of whitegrubs and cutworms was evaluated. The controlled release formulations of carbosulfan 10% and chlorpyrifos 10% at 1,0 g active ingredient/tree (a.i./tree), gamma BRC 0,6% dust at 0,06 g a.i./tree and the synthetic pyrethroid deltamethrin 5 % SC at 0,025 g a.i./tree were persistent and effective in controlling whitegrubs, even when applied early in the planting season. Deltamethrin 5 % SC at 0,025 g a.i./tree was also successful in controlling cutworms. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

Effects of forest disturbance on leaf shredding aquatic insects were investigated by comparing leaf biomass and shredder production in disturbed versus reference forest streams. Benthic samples were collected monthly in 3 streams in a mature hardwood reference forest and 3 streams in an 11-year-old clearcut. Reference forest streams had significantly greater total leaf biomass and significantly more slow-processing leaf material than disturbed forest streams. Disturbed forest streams had significantly greater fast-processing leaf biomass than did reference streams. The leaf shredding insects Tipula abdominalis, Pycnopsyche sp., and Tallaperla maria comprised over 90% of the shredder biomass in all streams. Total shredder production was Significantly greater (p<0.05) in disturbed versus reference streams. Production of Pycnopsyche and T. maria was significantly greater (p <0.10) in disturbed versus reference streams, but T. abdominalis production was not significantly different (po =0.28). Greater T. maria production was attributed mostly to better survivorship in disturbed versus reference streams. Greater total shredder production in disturbed streams was attributed mostly to greater production by Pycnopsyche, which was due mostly to better survivorship and growth of early instar larvae in disturbed streams. T. maria and T. abdominalis were studied under laboratory conditions to determine whether feeding on various types of leaf material would affect growth. Shredder growth rates were affected more by length of instream conditioning of leaves than leaf species or leaf exposure site. Each shredder species had different patterns of growth and survivorship relative to leaf species and conditioning. There was no difference in shredder growth patterns between early versus late successional leaf species. Pycnopsyche growth was not studied, but Pycnopsyche may be more capable than the other shredders of exploiting fast-processing, early successional leaf species. Pycnopsyche production was greatest in streams having the greatest quantities of early successional leaf biomass. Pycnopsyche biomass correlated significantly with fast-processing leaf biomass typical of the early successional forest, whereas other shredders did not. Shredder production was significantly greater in disturbed versus reference forest streams, even though total leaf biomass was significantly greater in reference streams. Providing that forest clearcutting is accomplished with minimal physical disturbance to streams, shredder populations may exhibit greater production in streams 11-years after forest clearcutting than in reference forest streams. / Ph. D.

O percevejo-bronzeado do eucalipto, Thaumastocoris peregrinus, é um inseto fitófago que ocasiona o amarelecimento das folhas de Eucalyptus e, em casos severos, a desfolha e morte das plantas. Buscam-se formas de controle natural e/ou biológico para o controle deste inseto. Nesta perspectiva, o controle biológico vem ganhando espaço e o emprego de fungos entomopatogênicos torna-se viável, uma vez que já ocorre naturalmente no ambiente. Nesse sentido, objetivou-se avaliar a ação do fungo entomopatogênico B. bassiana, isolado IBCB 66 sobre diferentes fases de desenvolvimento de T. peregrinus, em condições de laboratório. Os tratamentos foram: Água destilada esterilizada (ADE), Água destilada esterilizada + Tween® 80 (0,01%) (ADET) e B. bassiana isolado IBCB 66 (1,0 x 108 conídios. mL-1). Esses tratamentos foram avaliados em três bioensaios em delineamento inteiramente casualizado. 1- Ação de B. bassiana sobre ovos de T. peregrinus: Folhas de Eucalyptus benthamii foram recortadas em discos de 2,4cm Ø, alocados no interior de tubos de vidro chato (2,5cm Ø e 10 cm h). Cartelas contendo em média 10 ovos de T. peregrinus foram imersas na solução correspondente a cada tratamento e colocadas sobre os discos foliares, totalizando 20 repetições/tratamento, sendo mantidos em câmara climatizada BOD (27±2° C, 14 h de fotofase e UR de 70 ± 10%) (procedimento padrão para todos os bioensaios). Foram avaliados o período de incubação e a viabilidade dos ovos de T. peregrinus. 2- Ação de B. bassiana sobre ninfas de T. peregrinus: Discos de E. benthamii de 2,4cm Ø, previamente tratados foram alocados no interior de tubos de vidro que recebeu, na sequência, uma ninfa de 3° ínstar de T. peregrinus, totalizando 50 tubos/repetições por tratamento. Neste bioensaio foram avaliadas a duração e a viabilidade dos ínstares ninfais. 3- Ação de B. bassiana sobre adultos de T. peregrinus: este bioensaio foi realizado conforme metodologia descrita para ninfas. Cada tubo de vidro recebeu um adulto de T. peregrinus, totalizando 50 tubos/repetições por tratamento. Neste bioensaio foi avaliada a longevidade diariamente, até a mortalidade total dos insetos. Alguns exemplares de adultos mortos que entraram em contato com B. bassiana foram coletados, para análise histológica, conforme metodologia padrão. O fungo B. bassiana não interferiu no período de incubação e viabilidade de ovos de T. peregrinus. O mesmo foi observado sobre ninfas de 3° ínstar e adultos, que não foram afetados pelo fungo. A duração média e a viabilidade foram reduzidas em ninfas de 4° e 5° ínstar, demonstrando que o fungo B. bassiana é patogênico nessa fase de desenvolvimento. Na análise histológica de adultos de T. peregrinus verificou-se a presença de hifas, conídios e conidióforos nos tecidos do sistema digestivo e muscular. / The bronze bug of eucalyptus, Thaumastocoris peregrinus, is a phytophagous insect that causes yellowness of leaves of Eucalyptus, and in severe cases, death, and defoliation of plants. Forms of natural control and/or biological control for this insect are aimed. In this perspective, biological control has been increasing and the use of entomopathogenic fungi is feasible, as already occurs naturally in the environment. In this sense, it aimed to evaluate the action of entomopathogenic fungus B. bassiana, isolated IBCB 66 on different developmental stages of T. peregrinus in laboratory conditions. The treatments were: sterilized distilled water (SDW), Distilled water Tween 80 (0.01%) (DWT) and B. bassiana IBCB 66 (1.0 x 108 conidia mL-1). These treatments were evaluated in three bioassays in experimental design. 1: B. bassiana action on eggs of T. peregrinus: Eucalyptus benthamii leaves were cut into disks of 2.4 cm Ø, allocated within flat glass tubes (2.5 cm Ø and 10 cm h). Cards containing on average 10 eggs of T. peregrinus were immersed in the solution corresponding to each treatment and placed on leaf discs a total of 20 replications / treatment, and kept in a climatized chamber BOD (27 ± 2 ° C, 14 h photoperiod and RH 70 ± 10%) (standard procedure for all bioassays). They evaluated the incubation period and the viability of T. peregrinus eggs. 2: B. bassiana action on nymphs of T. peregrinus: E. benthamii discs of 2.4 cm Ø, pretreated were placed inside glass tubes that received following a nymph 3° instar T. peregrinus totaling 50 tubes / replications. In this bioassay were evaluated duration and viability of the nymphal instars. 3: B. bassiana action on adults of T. peregrinus: This bioassay was performed as described methodology for nymphs. Each glass tube received an adult T. peregrinus, totaling 50 tubes / replications per treatment. In this bioassay was assessed daily longevity to the total mortality of insects. Some adult specimens dead who came into contact with B. bassiana were collected for histologic analysis as standard methodology. B. bassiana did not affect the incubation period and viability of eggs of T. peregrinus. The same was observed on nymphs of 3° instar and adults who have not had the studied biological parameters affected by the fungus. The average duration and viability were reduced by 4 ° to 5 ° instar nymphs , indicating that the pathogen is B. bassiana this development phase. Histological examination of the adults of T. peregrinus verified the presence of hyphae, conidia and conidiophores in the digestive system and muscle tissues.

Dans l’hémisphère Nord, le climat des deux derniers millions d’années a été marqué par une alternance de périodes froides et de brefs intervalles chauds. Cette succession d’évènements a laissé des traces durables au niveau de l’arrangement spatial de la diversité et de la structure génétique au sein des espèces.<p>En décrivant la répartition spatiale des lignées d’une espèce au moyen d’informations génétiques, la phylogéographie vise à identifier les processus évolutifs responsables de cette répartition. La phylogéographie comparée permet de gagner en compréhension en confrontant les patrons de variation génétique présents chez plusieurs espèces codistribuées :en étudiant des espèces partageant une même histoire au moyen de plusieurs sources d’information indépendantes (par exemple, plusieurs fragments d’ADN ou des données bioclimatiques historiques externes), il est possible de mettre en évidence des éléments de cette histoire commune tels que des refuges glaciaires ou des routes de recolonnisation post-glaciaires. Par contre, il est aussi possible que les caractéristiques biologiques intrinsèques à chaque espèce, telles que des stratégies dispersives ou reproductives différentes, engendrent une différenciation dans la structure et la diversité de cette variation génétique. <p>Dans cette thèse de doctorat nous nous sommes intéressés à deux espèces inféodées à un même hôte (Picea abies) et appartenant à une même sous-famille taxonomique (Coleoptera :Curculionidae, Scolytinae). Il sagit du typographe, Ips typographus et du dendroctone, Dendroctonus micans. Au moyen de plusieurs fragments génétiques spécialement identifiés pour cette étude ainsi que par le recours à des modèles bioclimatiques et des tests statistiques basés sur la théorie de la coalescence, nous avons étudié la phylogéographie de ces espèces.<p>Les résultats obtenus au cours de ce travail ont permis de mettre en évidence l’influence contrastée de stratégies écologiques différentes sur l’arrangement de la variation génétique. Une espèce opportuniste aux capacités de dispersion élevées telle qu’I. typographus présente un patron génétique peu structuré (des variants génétiques appelés haplotypes sont présents dans des régions très disparates) et un degré de polymorphisme nucléaire relativement élevé. Au contraire, une espèce parasitique adaptée à un environnement stable et caractérisée par une stratégie de dispersion limitée telle que D. micans présente un patron génétique très structuré (un nombre restreints et spécifiques d’haplotypes sont observés dans des régions géographiquement proches) et un degré de polymorphisme nucléaire dramatiquement faible.<p>Par ailleurs la comparaison de nos résultats à ceux de leur hôte, l’épicéa, ainsi qu’à ceux d’autres espèces partageant une même niche écologique (ex. Rhizophagus grandis), nous a permis de mettre en évidence des éléments communs dans l’histoire de ces espèces boréo-montagnardes :les populations européennes et asiatiques présentent une même divergence ancienne (antérieure à la dernière glaciation) et les populations européennes affichent des traces de structure génétique. Ces éléments nous ont permis de reconsidérer l’histoire de ces deux espèces en proposant et testant de nouveaux scénarios historiques./In the North Hemisphere, the climate of the last two million years has been paced by<p>the alternation of ice ages and warm interglacial periods. This succession of events has markedly shaped the present-day spatial arrangement of genetic diversity and structure within species. <p>By analyzing the geographical distribution of genetic variation within species, Phylogeography aims to identify evolutionary processes responsible for the current spatial patterns in the distribution of populations. Comparative phylogeography is used to gain insights into the understanding of driving evolutionary processes by co-analyzing the current genetic variation patterns of several co-distributed species; the study of species sharing a same history by several independent sources of information (e.g. different DNA fragments or historical bioclimatic data) allows to identify similar historical events such as glacial refugia or post-glacial recolonization pathways. However differences in life-history traits related to specific ecological strategies may also influence contrasting patterns of genetic structure and diversity. <p>In this PhD thesis, we focused on two insect associated with a same host (Picea abies) and belonging to a same taxonomic sub-familly (Coleoptera :Curculionidae, Scolytinae). The two insects are the Eurasian spruce bark beetle, Ips typographus, and the great spruce bark beetle, Dendroctonus micans. By the use of several genetic markers specifically designed for the purpose of this study and by bioclimatic modeling approach combined with coalescent-based statistical method, we have studied the phylogeography of both species. <p>Our results enable us to highlight the influence of contrasting ecological strategies on the spatial arrangement of genetic variation. On the one hand, opportunistic species characterized by high dispersal capacities, such as I. typographus, exhibits poor genetic structure (same genetic variants named haplotypes are found in really distant geographic regions) and a relatively high polymorphism level. On the other hand, parasitic species well-adapted to stable environmental conditions and characterized by limited dispersal strategy, such as D. micans, exhibits high genetic structure (same specific haplotypes found in same or neighboring geographic countries) and an extremely low polymorphism level.<p>Moreover, the comparison of our results with those of their specific host plant Picea abies and of other sympatric species (e.g. Rhizophagus grandis), has enable us to identify common patterns typical of boreo-montane species :a same old divergence between european and asiatic populations (older than the last glaciation) and genetic structure in european populations. These findings have been used to infer past of both species by identifying and testing new historical scenarii.<p><p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

The Eurasian spruce bark beetle Dendroctonus micans is a major pest of spruce which is expanding its range in France, Turkey, England and Wales. Its monospecific predator Rhizophagus grandis has followed naturally the bark beetle into most areas and, since the 1960s, has also been mass-produced and successfully released within newly infested locations. <p>In this scope, the development of an effective trapping method would be very useful to assess the bark-beetle presence at previously uninfested sites, or predator establishment after release or natural spread. We demonstrated the efficiency of oxygenated monoterpenes-baited kairomone traps to monitor R. grandis in various epidemiological conditions, including areas localized behind or at the limit of the pest’s distribution, or in areas where artificial releases were performed. Because the predator is strictly species-specific, another exciting possibility offered by the kairomone trapping is the indirect monitoring of the pest itself in areas of unknown status (e.g. areas under colonization, or considered as at risk at medium- term).<p>R. grandis is also considered as one of the most valuable natural enemies to strike aggressive North-American Dendroctonus species. In this respect, R. grandis has been recently applied in a neo-classical biological program against the red turpentine beetle D. valens, which invaded China from North America in the late 1990’s. In laboratory tests conducted on pine logs in the laboratory, or on living pine trees in the field, we demonstrated that R. grandis adults can successfully enter and reproduce into D. valens galleries. <p>In Europe, R. grandis is the only species regularly found in the brood systems of D. micans, where adults and larvae attack the gregarious larvae of their prey. In such enclosed systems, R. grandis’ functional response is therefore influenced by various interrelated components, such as the prey density, the predator density, or the prey distribution. Measuring the predator’s success in terms of larval survival and growth rates, we demonstrated the time spent by R. grandis larvae to wound and kill their prey to be the main factor limiting their development. This factor may be considerably influenced by the proportions of diseased, wounded or molting prey rise in the brood system, for instance as a result of an increase in prey density, or due to the presence of conspecific adults (which wound their prey but do not consume them entirely). Furthermore, our tests suggest that no cannibalism or noticeable intraspecific competition occurred between R. grandis larvae, whereas some lighter mode of competition probably took place. <p>R. grandis also exhibits a reproductive numerical response to prey density, which mainly relies on the perception of chemical stimuli and inhibitors released in the bark beetle brood system. In the current study, we developed a non-destructive approach to follow the dynamics of volatile compound production, using sequential sample collection on SPME fibers. Our tests demonstrated that the larval activity of D. micans or D. valens strongly influences the release of some oxygenated monoterpenes. However, our attempts to correlate the relative quantities of some identified chemicals to offspring production were less successful as it concerns the identification of potential oviposition stimuli and inhibitors. <p>The problematic rose by the progression of D. micans, as well as detailed results of each of the described above studies are discussed in the two published papers and the three manuscripts forming this thesis. Bringing all these studies together, several perspectives are also presented in the general discussion. <p>/<p>Ravageur des épicéas, Dendroctonus micans est toujours en voie d’extension en France, en Turquie, en Angleterre et au Pays de Galles. Dans la plupart de ces zones, le dendroctone est accompagné de manière naturelle par son prédateur monospécifique, Rhizophagus grandis. Depuis les années 1960, le prédateur a également fait l’objet d’une production de masse et de programmes de lâchers dans les zones d’arrivée récente du scolyte.<p>Dans le cadre de la lutte biologique contre D. micans, les gestionnaires forestiers doivent donc estimer au plus tôt la présence du ravageur dans des zones jusque là indemnes, mais également vérifier l’établissement du prédateur par progression naturelle ou résultant d’introductions délibérées. Dans la présente étude, nous avons démontré l’efficacité de pièges d’interception appatés à l’aide de monoterpènes oxygénés pour la capture de R. grandis. Celle-ci s’est faite dans différentes conditions épidémiologiques, incluant notamment des zones situées en arrière du front de progression du scolyte et des zones où des lâchers artificiels ont été réalisés. Comme R. grandis est strictement inféodé au dendroctone, un autre avantage de la technique est la possibilité de réaliser un dépistage indirect du ravageur dans les zones où son statut est incertain (zones en cours de colonisation, ou considérées comme à risque à moyen terme).<p>Par ailleurs, R. grandis est également considéré comme un des meilleurs ennemis naturels potentiels pour lutter contre d’autres espèces de Dendroctonus aggressifs. Dans cette optique, R. grandis a été récemment utilisé dans un programme de lute biologique contre D. valens, ravageur invasif arrivé en Chine dans la fin des années 1990 en provenance d’Amérique du Nord. Nous avons démontré la capacité de R. grandis à s’introduire et à se reproduire dans les galeries de D. valens lors de tests de laboratoire, mais aussi sur des arbres vivants en pinèdes. <p>En Europe, R. grandis est strictement inféodé aux galeries de D. micans, où larves et adultes du prédateur s’attaquent aux larves grégaires du scolyte. Dans ce système clos, la réponse fonctionelle de R. grandis est influencée par plusieurs facteurs étroitement corrélés, la densité de proies, la densité de prédateurs, et la distribution des proies. En mesurant l’efficacité de prédation de R. grandis en termes de survie des larves et de taux de croissance, nous avons démontré l’influence sur leur développement du temps passé par les larves à blesser et à tuer leurs proies. Ce facteur est par ailleurs fortement dépendant de la proportion de larves malades, blessées ou en cours de mue au sein du système ;une proportion qui peut augmenter en réponse à une augmentation de la densité de proies, ou lorsque des adultes sont présents (ceux-ci blessent les proies mais ne les consomment pas entièrement). Enfin, nos tests suggèrent qu’il n’existe que peu de cannibalisme ou de compétition intraspécifique entre larves de R. grandis, tandis que des modes de compétition moins importants prennent vraisemblablement place.<p>R. grandis présente également une réponse numérique reproductive à la densité de proies disponibles, principalement basée sur la perception de stimuli et d’inhibiteurs présents dans les galeries du scolyte. Par la collecte de composés volatils présents dans ces systèmes à l’aide de fibres SPME, nous avons développé une méthode non-destructive pour suivre la dynamique de production des médiateurs chimiques. Nos tests ont démontré que l’activité des larves de D. micans ou D. valens influence fortement la dynamique de production de certains monoterpènes oxygénés. En revanche, il n’a pas été été possible de corréler les différents composés identifiés au nombre de larves de R. grandis présentes dans le système. <p>La problématique soulevée par la progression de D. micans, de même que les résultats détaillés de chacune des études décrites ci-dessus sont discutés dans les deux papiers publiés et les trois manuscrits formant cette thèse. Les différentes perspectives apportées par ce travail sont également présentées dans la discussion générale.<p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished