La Pyrale du Café, Prophantis smaragdina Butler (Lepidoptera: Crambidae: Spilomelinae), est un ravageur des cultures de café présent en Afrique subsaharienne. A La Réunion, P. smaragdina est le principal insecte ravageur de la culture du caféier ‘Bourbon Pointu’, café de haute qualité reconnu à l'échelle internationale. Le plan gouvernemental ECOPHYTO, ajouté aux enjeux environnementaux, contraignent les producteurs de café à réduire l'utilisation de pesticides qui est la seule solution efficace actuelle contre P. smaragdina. Cette thèse a été entreprise afin d'améliorer nos connaissances sur la bio-écologie et l'écologie chimique de P. smaragdina afin de développer une méthode de lutte biologique contre cet insecte. L'étude de la biologie a montré que la population de P. smaragdina était la plus importante au début de la période de fructification c'est-à-dire en janvier. Une corrélation positive entre la température et la densité de population a été montrée. Quatre parasitoïdes de P. smaragdina ont été identifiés à La Réunion. Parmi eux, Pristomerus rivier (Hymenoptera: Ichneumonidae) est révélé comme parasitoïde candidat pour une éventuelle lutte contre P. smaragdina par l'utilisation d’ennemis naturels. Les observations du comportement d’accouplement ont montré que, comme la plupart des lépidoptères hétérocères, la femelle attirait le mâle par l'émission d'une phéromone sexuelle. Quatre molécules suspectés de composer la phéromone femelle ont été identifiées par chromatographie en phase gazeuse couplé à la spectrométrie de masse (GC/MS). Les tests d'électroantennographie (EAG) ont montré que le composé majoritaire identifié induisait une réponse significative des antennes mâles, le faisant candidat pour être le composé majoritaire de la phéromone femelle de P. smaragdina. Les tests de piégeage au champ avec les composés identifiés n'ont, jusque-là, pas entrainé de captures, probablement à cause d’un composé mineur manquant ou d'un mauvais ratio de composés dans les pièges. Il est suggéré que le mâle P. smaragdina émet une phéromone pendant le comportement de cour. L'analyse GC/MS des composés volatiles de pinceaux androconiaux des mâles a mis en évidence cinq composés aromatiques. Les tests EAG des composés identifiés sur les antennes des mâles et des femelles suggèrent que le créosol pourrait jouer un rôle sur les comportements du mâle et de la femelle. / The Coffee berry moth, Prophantis smaragdina (Lepidoptera: Crambidae: Spilomelinae) is an important pest of coffee mainly recorded in sub-Saharan Africa. In Reunion Island, P. smaragdina is the only insect pest of coffee. P. smaragdina larvae, by eating coffee cherry albumen, cause major yield losses in ‘Bourbon Pointu’ (BP) production, which is a high value-added and internationally known coffee. Governmental ECOPHYTO plan, added to environmental concerns, constrain coffee farmers to reduce insecticide spraying which is, until now, the only efficient control method of P. smaragdina. This thesis was undertaken to improve our knowledge of the bio-ecology and chemical ecology of P. smaragdina to develop an efficient and economically sustainable biocontrol method against this insect. Our bio-ecology study showed that P. smaragdina population was the most abundant at the beginning of BP fructification period i.e in January. A positive correlation between temperature and P. smaragdina population density was showed. Four parasitoids of P. smaragdina in Reunion were identified. Among them, Pristomerus rivier (Hymenoptera: Ichneumonidae) is a potential candidate for P. smaragdina biocontrol. Mating behaviour observations showed that, as most of moths, the female emits a sexual pheromone to attract males for mating. Four compounds suspected to compose the female pheromone identified using gas chromatography coupled with mass spectrometry (GC/ MS). Electroantennography (EAG) test on male showed that the major identified compound induced a response of male antennae, it could be the major compound of P. smaragdina female pheromone. Field trapping tests with identified compounds, until now, did not yield any captures, probably because of a lack of minor pheromone components or because of erroneous compounds ratios used in traps. A study of P. smaragdina courtship behaviour suggested that the male of P. smaragdina emits pheromone. Five aromatic compounds were identified in male hair pencil volatiles by GC/MS. EAG tests of those compounds on male and female antennae suggest that creosol could play a role on male and female behaviour.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Organo-synthetic insecticides are widely used to control pests in crops and stored products. The indiscriminate use of these products are responsible for many economic and environmental problems, which has been generating a growing demand for alternative control methods. The essential oils of plants have been studied as a viable alternative to pest management. Recent jobs indicate that the essential oil of alecrim-de-tabuleiro Lippia gracilis presents great potential for biopospection insecticide compounds. Thus, the aim of the present work was study the essential oils of two chemotypes of L. gracilis and their major compounds thymol and carvacrol, evaluating: i) the toxicity of these compounds against Diaphania hyalinata and selectivity over non-target organisms Apis mellifera and Polybia micans ii) the toxicity and behavioral effects of these compounds over Cryptolestes ferrugineus. The essential oils of both chemotypes of L. gracilis were toxic to D. hyalinata. The carvacrol chemotype was 29% more toxic than thymol chemotype. The monoterpenes thymol and carvacrol when applied alone, were about two and five times more toxic than their respective chemotypes. Essential oils acted very quickly causing mortality in half the population of D. hyalinata in less than three hours. All treatments were not selective in favor of A. mellifera and P. micans. The essential oils and the major compounds were highly toxic by fumigation to adults of C. ferrugineus. The concentrations of the thymol and carvacrol chemotypes required to cause 50% mortality of C. ferrugineus were 20.7 and 25.1 μL L-1, respectively. The isolated thymol and carvacrol were 1.7 and 1.9 times more toxic to C. ferrugineus. Essential oils thymol and carvacrol chemotypes caused a mortality half the population of C. ferrugineus in 63.3 and 83.1 hours. All treatments caused repellency and irritability in adult C. ferrugineus. Thus, our results show the great potential of essential oils of L. gracilis and their major compounds for the development of new products to be used in the pest control field and in stored products. / Inseticidas organossintéticos são amplamente utilizados no controle de pragas em lavouras e em produtos armazenados. O uso abusivo destes produtos é responsável por diversos problemas econômicos e ambientais, o que tem gerado uma demanda crescente por métodos alternativos de controle. Os óleos essenciais de plantas têm sido estudados como uma alternativa viável ao manejo de pragas. Trabalhos recentes apontam que o óleo essencial do alecrim-de-tabuleiro Lippia gracilis apresenta grande potencial para bioprospecção de compostos inseticidas. Desta forma, objetivou-se neste trabalho estudar os óleos essenciais de dois quimiotipos de L. gracilis e seus compostos majoritários timol e carvacrol, avaliando: i) a toxicidade destes compostos sobre Diaphania hyalinata e a seletividade sobre os organismos não-alvos Apis mellifera e Polybia micans; e ii) a toxicidade e os efeitos comportamentais destes compostos sobre Cryptolestes ferrugineus. Os óleos essenciais de ambos quimiotipos de L. gracilis se mostraram tóxicos a D. hyalinata, sendo o quimiotipo carvacrol 29% mais tóxico do que o quimiotipo timol. Os monoterpenos timol e carvacrol quando aplicados isoladamente foram cerca de duas e cinco vezes mais tóxicos que seus quimiotipos, respectivamente. Os óleos essenciais atuaram de forma rápida causando mortalidade na metade da população de D. hyalinata em menos de três horas. Todos os tratamentos não foram seletivos à A. mellífera e P. micans. Os óleos essenciais e os compostos majoritários foram altamente tóxicos por fumigação aos adultos de C. ferrugineus. As concentrações dos óleos essenciais dos quimiotipos timol e carvacrol necessárias para causar 50% de mortalidade a C. ferrugineus foram 20,7 e 25,1 μL L-1, respectivamante. O timol e o carvacrol isolados foram 1,7 e 1,9 vezes mais tóxicos a C. ferrugineus. Os óleos essenciais dos quimiotipos timol e carvacrol causaram mortalidade em metade da população de C. ferrugineus em 63,3 e 83,1 horas. Todos os tratamentos causaram repelência e irritabilidade em adultos de C. ferrugineus. Assim, nossos resultados mostram o grande potencial dos óleos essenciais de L. gracilis e seus compostos majoritários para o desenvolvimento de novos produtos a serem utilizados no controle de pragas em campo e nos produtos armazenados.