Harmonia axyridis is a ladybird native to Asia, but introduced widely as a biocontrol agent. It is invasive and detrimental to native species in North America, which meant its arrival in Britain was met with concern. Establishment was seen as an opportunity to track the spread of an invasive alien species (IAS) whilst also monitoring impacts on native species. The aims of this thesis were to examine the responses of native British ladybirds to the arrival of H. axyridis, to establish the effect of the IAS on native ladybirds when compared to other drivers, and to investigate the possible facilitation of the H. axyridis invasion by natural enemy release. Modelling ladybird distributions with life-history and resource-use traits found that species predatory on a wide range of prey families had larger range sizes than those which ate fewer prey types. This suggests that the wide diet breadth of the IAS is likely to have played a critical role in the species’ rapid spread. Dietary niche overlap between H. axyridis and native ladybirds showed positive correlation with declines of native ladybirds. This indicates that the IAS is playing an important role, but the significance of urbanisation suggests habitat destruction is also significant. Abundance of H. axyridis was influenced by habitat type and aphid abundance, but not by the native ladybird community, suggesting the spread of the IAS will not be slowed by biotic resistance. Harmonia axyridis is attacked by native parasitoids, but at a much lower rate than is the native Coccinella septempunctata, in line with natural-enemy release theory. There was no evidence of attack rate increasing with time since arrival in an area. Overall, H. axyridis is an extremely successful IAS, with detrimental effects on native ladybirds which are likely to continue.

Made available in DSpace on 2017-07-10T18:13:25Z (GMT). No. of bitstreams: 1 Sidnei Klein.pdf: 674707 bytes, checksum: 12d531ad9dbec523abd994dd964a51c8 (MD5) Previous issue date: 2011-02-18 / Itaipu Binacional / The present study aimed evaluate the performance of pacu (Piaractus mesopotamicus) reared in cages in the Itaipu Reservoir, fed diets with different protein levels. The experiment was conducted at the Centre for Development of Technology for fish farming in cages, located along the Biological Refuge of Santa Helena - PR, for a period of 74 days. We used 2.000 fish with average weight of 150,5 ± 2,1 g distributed in a completely randomized design with five treatments and four replicates in 20 cages, with 5,0 m3 of usable volume, and the experimental unit consists of a tank with 100 fish. The treatments consisted of five extruded feeds with different crude protein levels (18,5; 20,7; 23,7; 25,6; and 28,3%). The feeding was performed three times daily until satiation of the animals. After the experiment were measured the parameters of growth performance, hematology, carcass yield and fillet chemical composition. The Average final weight, weight gain and daily weight gain was statistically different (P<0,05), showing a quadratic effect. We used linear effect on feed conversion. After the derivation of the equations the average final weight was greater for fish fed 25,9% CP and greater weight gain was observed with 25,8% CP. The parameters of carcass yield showed no significant difference (P>0,05). For chemical composition only moisture and ether extract showed significant differences, showing a linear effect for both, with an inverse correlation between these parameters, as increased levels of protein in the diet increased moisture and decreased the ether extract. There were no statistical differences in the hematological and biochemical variables, showing that protein levels contained in the diets did not influence the physiological status of fish. According to the results, we recommend the use of feed containing 25,8% crude protein for pacu (P. mesopotamicus) juvenile, reared in cages system. / O presente estudo objetivou avaliar o desempenho produtivo de pacus (Piaractus mesopotamicus) cultivados em tanques rede no reservatório da Itaipu Binacional, alimentados com rações contendo diferentes níveis de proteína bruta. O experimento foi realizado no Centro de Desenvolvimento de Tecnologia para Piscicultura em Tanques rede, localizado junto ao Refúgio Biológico de Santa Helena - PR, por um período de 74 dias. Foram utilizados 2.000 peixes com peso médio de 150,5±2,1g distribuídos em um delineamento inteiramente casualizado com cinco tratamentos e quatro repetições em 20 tanques rede, com 5,0 m³ de volume útil por tanque rede, sendo a unidade experimental composta por um tanque com 100 peixes. Os tratamentos foram constituídos por cinco rações extrusadas com diferentes níveis de proteína bruta (18,5; 20,7; 23,7; 25,6 e 28,3 %). O arraçoamento foi efetuado três vezes ao dia, até a saciedade aparente dos animais. Ao término do experimento foram aferidos os parâmetros de desempenho zootécnico, rendimento de carcaça, composição química dos filés e hematologia. O peso final médio, ganho de peso e ganho de peso diário apresentaram efeito quadrático (p<0,05). Foram observados efeito linear para conversão alimentar. Após a derivação das equações o maior peso final médio ocorreu para peixes alimentados com 25,9% PB e o maior ganho de peso foi observado com 25,8% PB. Os parâmetros de rendimento de carcaça não apresentaram diferenças significativas (p>0,05). Para composição química a umidade e o extrato etéreo apresentaram efeito linear, com relação inversa entre estes parâmetros. O aumento do nível de proteína bruta na dieta elevou o percentual de umidade e reduziu a porcentagem de extrato etéreo. Não foram observadas diferenças estatísticas para as variáveis hematológicas e bioquímicas, demonstrando que os níveis protéicos contidos nas dietas não influenciaram na higidez dos peixes. De acordo com os resultados obtidos, recomenda-se a utilização de ração contendo 25,8% de proteína bruta para juvenis de pacu (P. mesopotamicus), criados em sistema de tanques rede.

Les fourmis sont des organismes cibles appropriés pour les études environnementales. Au cours de notre étude, nous nous sommes focalisés sur les fourmis de la litière via l'application de deux méthodes de récolte complémentaires selon le protocole all (ants of leaf litter). Dans les forêts naturelles de Guyane française, l'hétérogénéité environnementale et les perturbations structurent les communautés de fourmis de la litière en influençant la richesse, la diversité, l'abondance et la densité en espèces ainsi que les compositions taxonomique et fonctionnelle. Chaque type de formation végétale possède une communauté spécifique. La fragmentation et la conversion des forêts en plantations ont entrainé une altération plus ou moins profonde des communautés; cette variabilité est fonction du type d’agriculture et des espèces d'essences cultivées. Bien que l'altération des communautés se soit révélée maximale dans la plupart des monocultures, les plantations de cacaoyers ont un potentiel de conservation réel. Enfin, dans un contexte ou il est urgent de simplifier l'intégration des arthropodes dans les études de conservation, de contrôle et de suivi de la santé des écosystèmes terrestres, la méthode des réseaux de neurones est apparue comme un outil puissant pour mettre en évidence et analyser les patrons des communautés de fourmis. / Ants are reliable and relevant target organisms for environmental surveys. In our study, we focused on litter-dwelling ants through the use of two complementary sampling methods that were implemented according to the ants of leaf litter (all) protocol. In pristine forests of french guiana, leaf-litter ant communities are structured by environmental heterogeneity and natural perturbations - which influence species richness, diversity, abundance and density, as well as taxonomic and functional composition. This results in habitat-specific communities for each vegetal formation. Forest fragmentation and conversion into monocultures have led to a more or less deep alteration of the ant communities; this variability depends on the type of agricultural system and cultivated tree species. Although the intensity of community alteration peaked in tree monocultures, cocoa plantation exhibited a real potential for native species conservation. Finally, in the current context where simplifying the integration of arthropods into conservation programs as well as into surveys designed to monitor and manage the environment is critical, the use of neural networks appears to be a powerful tool for reliably highlighting and analyzing ant communities patterns.

During the 1990s, over a period of just a few years, the multi-colored Asian lady beetle, Harmonia axyridis (Pallas) invaded the entire area of northern Europe. In parallel with this invasion, a decline in native coccinellid species was recorded in Belgium, Britain, and Switzerland, affecting mainly one common species: the two-spot ladybird, Adalia bipunctata L. An impressive trait of H. axyridis, that could explain both its high invasiveness and the decline of native coccinellids, is its predation behaviour. Intraguild predation is a trophic interaction between species that share the same prey – in this case, aphids. In order to determine the precise impact of this predation on the native coccinellid species, the predation behaviour of H. axyridis larvae was observed in Petri dishes and on plants. The resistance of H. axyridis to predation was also studied by exposing it without dorsal spines to native predator larvae, in order to test whether or not the dorsal spines are a physical defence against intraguild predation. In addition to these laboratory experiments, an original method was developed and used to track predation under field conditions. This method is based on the gas chromatography–mass spectrometry (GC-MS) detection of exogenous alkaloids in H. axyridis, especially alkaloids from native coccinellids likely to be subject to intraguild predation. My results show that, in the absence of aphids, H. axyridis consumes both A. bipunctata eggs and all larval instars in Petri dishes. On plants, depending to aphid density, this interaction can change with regards to larvae but not eggs. In addition to intraguild predation, competitive exclusion can occur because of quite aggressive behaviour towards competitors. Dorsal spines significantly reduce the number of bites inflicted, and thereby complement the other defense mechanisms of H. axyridis that enable it to remain dominant in competition for food resources. In semi-natural conditions, predation on the native coccinellids Adalia spp. Calvia spp. Coccinella septempunctata L. and Propylea quatuordecimpunctata (L.) was detected. The number of sites where this predation was observed suggests that this interaction is frequent. It was also observed that an H. axyridis larva can ingest several native coccinellid species, confirming its status as a predator of coccinellids. We can therefore conclude that intraguild predation by H. axyridis leads, as does resource competition, to a decline in native coccinellids./Introduite pour la lutte biologique dans les années 90, la Coccinelle asiatique, Harmonia axyridis (Pallas), a envahi en quelques années toute l’Europe du Nord. Parallèlement à cette invasion, un déclin de plusieurs espèces de coccinelles indigènes dont la très commune Coccinelle à deux points, Adalia bipunctata L. a été observé dans différents biotopes en Belgique, en Angleterre ainsi qu’en Suisse. Un des traits remarquables de la Coccinelle asiatique est son comportement de prédateur intraguilde qui pourrait expliquer à la fois ce déclin mais aussi en partie son caractère hautement invasif. La prédation intraguilde est une interaction trophique entre des espèces qui se nourrissent d’une même proie, dans ce cas-ci les pucerons. Afin de mieux connaître l’impact de cette prédation sur les coccinelles indigènes, le comportement de prédation des larves d’H. axyridis a été décrit en boîtes de Petri et sur plantes. Sa résistance à la prédation a également été étudiée en exposant des larves dépourvues d’épines dorsales à un prédateur indigène, dans le but de tester le rôle de ces épines en tant que défense physique à l’égard d’un prédateur intraguilde. En plus de ces expériences de laboratoire, une méthode originale a été développée et utilisée pour suivre cette prédation en conditions semi-naturelles. Elle se base sur la détection, en GC-MS, des alcaloïdes exogènes chez H. axyridis et en particulier des alcaloïdes produits par d'autres espèces de coccinelles susceptibles de subir une prédation intraguilde. Mes résultats montrent qu'en l'absence de pucerons, H. axyridis a un comportement de prédation vis-à-vis des œufs et de tous les stades larvaires d’A. bipunctata. La présence de pucerons, suivant leur densité, peut modifier cette interaction à l’égard des larves indigènes mais pas des œufs. En plus de la prédation intraguilde, une compétition par exclusion peut être aussi suspectée et expliquée par le comportement très agressif d’H. axyridis à l’égard de ses concurrents. Quant aux épines dorsales, elles permettent de réduire significativement le nombre de morsures et complètent ainsi les autres lignes de défense utilisées par H. axyridis pour s’imposer dans des ressources déjà exploitées par d’autres prédateurs. En conditions semi-naturelles, cette prédation à l’égard des coccinelles indigènes a été confirmée vis-à-vis d’Adalia spp. Calvia spp. Coccinella septempunctata L. et Propylea quatuordecimpunctata (L.). Vu le nombre de sites où cette prédation a été détectée, elle peut être considérée comme une interaction fréquente. De plus, une même larve de coccinelle asiatique peut ingérer plusieurs espèces de coccinelles indigènes confirmant indéniablement son statut de prédateur de coccinelles. Ainsi, nous pouvons conclure que la prédation intraguilde par H. axyridis sur les coccinelles indigènes participe très certainement au déclin de celles-ci et ceci très probablement au même titre que des phénomènes de compétition pour les ressources. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished