Made available in DSpace on 2015-03-26T13:30:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 312561 bytes, checksum: 2e92c15ccad6dade9bfe3f5f4800f1bc (MD5) Previous issue date: 2009-02-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research was conducted in the Laboratory of Insects Rearing (LACRI), of the Brazilian Company of Agricultural Research (EMBRAPA Maize and Sorghum Research Center) in Sete Lagoas, Minas Gerais State, Brazil. The objective was to study biological aspects of the immature phase of Eriopis connexa (Germar) (Coleoptera: Coccinellidae), with different artificial diets or preys common to the brazilian corn and sorghum agroecosystems, to develop a rearing methodology and to generate information necessary to the introduction of the predator in the crop system. The experimental design was an entirely randomized blocks, with the larvae of predator maintained in an acclimatized room, under 25±1ºC, 70±10% RH and photophase of 12 hours. The artificial diets were based on ground pet food or diets based on water, brewer's yeast and honey, with or without the addition of ferrous sulphate (FeSO4), wheat germ and soybean flour. The preys offered to E. connexa were eggs (one day or six months frozen) of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae), eggs (fresh) of Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae); eggs (fresh, one day or six months frozen) of Spodoptera frugiperda, with or without scales; recently hatched caterpillars of S. frugiperda; nymphs of Rhopalosiphum maidis (Fitch) or Schizaphis graminum (Rondani) (Hemiptera: Aphididae). All food sources were support ad libitum to E. connexa. Artificial diets, separately, did not support the development of E. connexa. Recently hatched caterpillars of S. frugiperda or eggs of A. kuehniella (six months of freezing), separately or complemented with the artificial diets, were inadequate. Eggs of A. kuehniella frozen for one day, fresh eggs of D. saccharalis, fresh eggs of S. frugiperda without or with scales, frozen for one day or six months, nymphs of S. graminum and R. maidis provided adequate development of the immature phases of the predator, evidencing the polyphagous habit of E. connexa. The results obtained also indicated the nutritional requirements of the predator and can be used to explain the success or not of E. connexa in biological control programs. Eriopis connexa adapted to different food sources, and in the field, it would not be restricted to only one source; and in this way, it could modulate its alimentary regime with alternative food, which is important for the biological control and shows its potential to control corn and sorghum pests. / Esta pesquisa foi conduzida no Laboratório de Criação de Insetos (LACRI), da Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA Milho e Sorgo) em Sete Lagoas, Minas Gerais, Brasil. O objetivo foi estudar aspectos biológicos da fase imatura de Eriopis connexa (Germar) (Coleoptera: Coccinellidae), com diferentes dietas artificiais e presas comuns aos agroecossistemas de milho e de sorgo, visando desenvolver uma metodologia de criação e fornecer subsídios para a introdução desse predador nessasculturas. O delineamento experimental foi em blocos inteiramente casualisados, com as larvas desse predador mantidas em sala climatizada a 25±1ºC, 70±10% UR e fotofase de 12 horas. As dietas artificiais foram à base de pet food triturada e dietas contendo água, levedo de cerveja e mel, com presença ou ausência de sulfato ferroso (FeSO4), gérmen de trigo e farelo de soja. As presas oferecidas a E. connexa foram ovos de Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae), congelados por um dia ou por seis meses; ovos frescos de Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae); ovos de Spodoptera frugiperda frescos, sem ou com escamas, congelados por um dia ou por seis meses; lagartas recém-eclodidas de S. frugiperda; ninfas de Rhopalosiphum maidis (Fitch) ou Schizaphis graminum (Rondani) (Hemiptera: Aphididae). Todas as presas e dietas artificiais foram oferecidas ad libitum a E. connexa. As dietas artificiais, isoladamente, não proporcionaram o desenvolvimento de E. connexa e lagartas recémeclodidas de S. frugiperda ou ovos de A. kuehniella (seis meses de congelamento), isoladamente ou complementados com as dietas artificiais, foram inadequados. Ovos de A. kuehniella congelados por um dia, ovos frescos de D. saccharalis, ovos de S. frugiperda frescos sem ou com escamas, congelados por um dia ou por seis meses, ninfas de S. graminum e R. maidis proporcionaram desenvolvimento adequado das fases imaturas desse predador, evidenciando o hábito polífago de E. connexa. Estudos como esse fornecem informações básicas sobre presas que suprem os requisitos nutricionais desse predador e explicações para a falha ou sucesso de E. connexa em programas de controle biológico. Eriopis connexa se adaptou a vários alimentos e, no campo, esse predador não seria restrito a um único alimento; e dessa forma, poderia modular seu regime alimentar com alimentos alternativos, o que é importante para o controle biológico e evidencia seu potencial para controlar pragas de milho e de sorgo.

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

Dans le cadre de ce travail, nous avons poursuivi l’étude de la biosynthèse d’alcaloïdes défensifs des coccinelles. Trois espèces ont été plus particulièrement étudiées :Adalia bipunctata (qui produit l’adaline [32]), Coccinella septempunctata (contenant la coccinelline [29]) et Harmonia axyridis (produisant l’harmonine [34]).<p>Afin d’identifier le (ou les) acide(s) gras précurseur(s) de ces alcaloïdes, nous avons dans un premier temps synthétisé des acides gras spécifiquement marqués. Nous avons ainsi préparé les acides [14-3H]myristique, [16-3H]palmitique, [18-3H]stéarique, [18-13C]stéarique et [11,11,12,12,13,13,14,14,15,15,16, 16,17,17,18,18,18-2H]stéarique.<p>Les différents acides gras marqués au tritium sur le méthyle terminal ont ensuite été incorporés successivement chez les trois espèces de coccinelles mentionnées ci-dessus, en utilisant la technique d’incorporation in vitro mise au point par Laurent et al. ( )<p>Les incorporations chez Adalia bipunctata ont montré que l’acide myristique est incorporé préférentiellement dans l’adaline. <p>Chez Coccinella septempunctata par contre, l’acide stéarique est incorporé dans la coccinelline environ 25 fois plus efficacement que les acides myristique et palmitique.<p>Enfin, les incorporations chez Harmonia axyridis ont établi que l’acide stéarique est le précurseur de l’harmonine. De plus, grâce à l’incorporation de l’acide [11,11,12,12,13,13,14,14,15,15,16,16,17,17,18,18,18-2H]stéarique, le mécanisme de formation de l’amine secondaire a été précisé.<p>/<p>In spite of their red-orange colors, which could increase risks of predation, Coccinellidae are rarely exploited as food sources by predators. Many of them owe their protection, at least in part, to the presence of repellents and, in some cases, toxic alkaloids in the hemolymph emitted during a process called "reflex bleeding". Previous studies have shown that the biosynthesis of these alkaloids is related to fatty acid metabolism. <p>In our doctoral thesis, we wanted to clarify what are the fatty acids precursors of adaline (Adalia bipunctata), coccinelline (Coccinella septempunctata) and harmonine (Harmonia axyridis), with the use of various techniques of labelling (3H, D, 13C, etc.).<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Predatory Ground beetles (Coleoptera: Carabidae) and Lady beetles (Coleoptera: Coccinellidae) are two of the most diverse groups found in wheat agroecosystems, globally. These groups are important from both an economic and ecological perspective due to their natural services provision. The effect of wheat agroecosystem management on species diversity, abundance, biomass and composition in South Africa is not yet documented, and there is no existing data indicating which predatory carabid and coccinellid species provides essential ecosystem services and bioindicator roles. Therefore, we examined the effects of organic, conventional and intercropped agroecosystems on ground beetle and lady beetle abundance, dried weight (biomass), composition and diversity. Sampling of wheat agroecosystems was conducted in three systems i.e. organic, conventional and organic intercropped. Post-hoc Tukey test indicated a statistically significant difference between species diversity, biomass and abundance in organic and intercropped systems compared to the conventional systems. Regression analysis indicated significant positive correlation between aphid’s density and predatory carabid and coccinellid beetles in the intercropped systems. Amongst the weather factors temperature influenced aphid density and carabid and coccinellid beetles’ abundance. PCA (Principal Component Analysis) revealed significant positive correlation between individual biomass and cropping system. Conventional system showed a negative correlations with carabid and coccinellid individual biomass. We found that some carabid and coccinellid species can be used to measure the quality of agroecosystems. This study provides a fundamental basis for identification and monitoring of carabid and coccinellid species and their role as bioindicators of ecological disturbance. The identified bioindicator species in this study can assist in developing conservation and biomonitoring strategies within agroecosystems. / Agriculture and  Animal Health / M. Sc. (Agriculture)