Orientador: Sérgio Antonio de Bortoli / Coorientador: Nelson Wanderley Perioto / Banca: Enrico de Beni Arrigoni / Banca: Rogéria Inês Rosa Lara / Banca: Luis Garrigos Leite / Banca: Ricardo Antonio Polanczyk / Resumo: Visando melhorias qualitativas na criação de Cotesia flavipes Cameron, 1891, realizaram-se testes com alimentação de adultos antes do parasitismo em Diatraea saccharalis Fabricius,1794, com 14 dietas: (2,5%; 5% e 10% sacarose; 2,5%; 5% e 10% sacarose + 2,5% lêvedo de cerveja; 2,5%; 5% e 10% mel; 2,5%; 5% e 10% mel + 2,5% lêvedo de cerveja; 2,5% lêvedo de cerveja; água) e testemunha. Avaliaramse: adultos emergidos, razão sexual, porcentagem de emergência, peso das massas de pupas e a longevidade nas gerações F1 e F2. O delineamento foi o inteiramente casualizado com 15 tratamentos e cinco repetições. As dietas a base de 5% de sacarose, 5 e 10% de mel aos adultos de C. flavipes podem proporcionar acréscimo considerável na longevidade dos parasitoides. O consumo de dietas artificiais por C. flavipes antes do parasitismo em D. saccharalis proporcionou melhorias qualitativas. O estudo visou ainda testar um protocolo de qualidade de C. flavipes, quanto à eficiência na busca pelo hospedeiro D. saccharalis. Foi usada uma arena de testes (copo plástico translúcido de 700 mL, com tampa). Lagartas de D. saccharalis foram colocadas em tolete de cana-de-açúcar de 13 cm, perfurado transversalmente e oferecidas ao parasitoide. Os tratamentos foram: (0, 6, 12, 18 e 24 horas de fotofase - L), (6, 12, 18 e 24 horas de disponibilidade do hospedeiro - H), (1, 2, 3, 4 e 5 lagartas por arena - T) e o orifício de entrada da lagarta na cana-de-açúcar (aberto - A ou fechado - F). Foram realizados os testes de Kolmogorov e a homogeneidade da variância foi analisada pelo teste de Bartlett, além das análises de agrupamento e de componentes principais. Foi criado um Índice de performance da qualidade (IPQ), que foi determinante na escolha do melhor tratamento. Foi proposto, o uso do tratamento: 6 horas de disponibilidade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Aiming at qualitative improvements in the rearing of Cotesia flavipes, tests were carried out with adults feed before parasitism in Diatraea saccharalis, with 14 diets (2.5%, 5% and 10% sucrose, 2.5%, 5% and 10% sucrose + 2.5% brewer's yeast, 2.5%, 5% and 10% honey, 2.5%, 5% and 10% honey + 2.5% yeast, 2.5% yeast, water) and control. Were evaluated: emerging adults, sex ratio, percentage of emergency, mass weight of pupae, and longevity in F1 and F2 generations. The design was completely randomized with 15 treatments and five repetitions. The diets based on 5% sucrose, 5 and 10% honey to adults of C. flavipes, may provide considerable increase in longevity. Consumption of artificial diets by C. flavipes before parasitism in D. saccharalis provides quality improvements. The study also aimed to test a protocol for quality of C. flavipes, for efficiency in the search for host D. saccharalis. We used a testing arena (700 mL plastic cup with lid). Larvae of D. saccharalis were placed in 13 cm cutting canes, drilled across, and offered to the parasitoid. The treatments were: (0, 6, 12, 18 and 24 hours of photophase - L) (6, 12, 18 and 24 hours of availability of the host - H) (1, 2, 3, 4 and 5 larvae per arena - T) and the entrance hole of the larvae in sugar cane (open - A or closed - F). We performed the Kolmogorov's test and the homogeneity of variance was analyzed by Bartlett's test. Were also carried out cluster analysis and principal components. It created an index of performance quality (IPQ). It is proposed the use of treatment 6 hours of availability, 0 hours of light, one larvae per arena, using the cutting cane with the hole closed, as quality protocol C. flavipes / Doutor

Submitted by (edna.saturno@ufrpe.br) on 2016-11-23T15:10:01Z No. of bitstreams: 1 Cinthia Conceicao Matias da Silva.pdf: 321146 bytes, checksum: e36e95044fe468bf9019c0b4774eac46 (MD5) / Made available in DSpace on 2016-11-23T15:10:01Z (GMT). No. of bitstreams: 1 Cinthia Conceicao Matias da Silva.pdf: 321146 bytes, checksum: e36e95044fe468bf9019c0b4774eac46 (MD5) Previous issue date: 2009-02-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This complex of sugarcane borers, in Brazil, comprises Diatraea saccharalis (Fabr.) and Diatraea flavipennella (Box) (Lepidoptera.: Crambidae). The control of borers, in Brazil, is the applied biological control using the larval endoparasitoid Cotesia flavipes (Cam.) (Hymenoptera: Braconidae). Recently, however, the biological control of D. flavipennella by the C. flavipes has been in discussion due to increasing occurrence of this borer species in the sugarcane fields across the northeast of Brazil. Thus, this study investigated the parasitism behavior of the parasitoid C. flavipes towards D. flavipennella side by side to D. saccharalis as well as determined its fertility life table parasitizing both hosts to clearify about this question. The parasitism behavior included free choice and host finding tests with and without visual cues, using arena in the laboratory. Larvae of D. saccharalis and D. flavipennella were exposed to 24h-old C. flavipes females, mated and fed. The free choice test consisted of an arena containing larvae of both sugarcane borers andcontrasted parasitoid wasp emerged from each one. The host finding test was conducted in an arena designed to not allow visual cues to the wasps. The parasitoid wasp in both tests showed no parasitism preference toward a sugarcane borer species being able to find and parasitize both borers similarly. The fertility life table parameters for C. flavipes parasitizing D. saccharalis andD. flavipennella were estimated based on the development and the specific daily parasitism obtained in the laboratory. The results show that C. flavipes exhibited similar parasitism and fertility on both borers, but with longer mean generation time and lower cocoon viability parasitizing D. flavipennella. Based on the results of the parasitism behavior and fertility life tablewe conclude that the parasitism of C. flavipes on D. flavipennella was not compromised. / As espécies Diatraea saccharalis (Fabr.) e Diatraea flavipennella (Box) (Lepidoptera: Crambidae) encontram-se distribuídas em todo o Brasil e no Nordeste, respectivamente. O controle dessas brocas, no Brasil, é a liberação do parasitóide Cotesia flavipes (Cam.) (Hymenoptera: Braconidae). No entanto, mais recentemente o controle de D. flavipennella com C. flavipes tem sido questionado em virtude da crescente ocorrência desta espécie nos canaviais do nordeste do Brasil. Assim, este trabalho investigou o desempenho de C. flavipes em D. saccharalis e D. flavipennella, com estudos de comportamento de escolha e parasitismo, bem como de biologia. Foram conduzidos estudos envolvendo testes de livre escolha para preferência e localização do hospedeiro em arenas. Lagartas das duas espécies de Diatraea foram ofertadas a fêmeas de C. flavipes com 24h de idade, acasaladas e alimentadas. Vespas criadas em lagartas de uma das brocas foram testadas individualmente, tendo como hospedeiro D. flavipennella e D.saccharalis, ou ambas as espécies. Os testes de localização do hospedeiro foram conduzindos usando arenas que permitiam as vespas utilizarem apenas pistas olfativas, pistas olfativas e visuais. Os resultados mostraram que as vespas não tiveram preferência de escolha, sendo C.flavipes capaz de localizar ambas as brocas. Em outro experimento, com dados de C. flavipes parasitando as duas brocas, foi confeccionada a tabela de vida de fertilidade do parasitóide nas duas espécies de Diatraea. A partir dos resultados encontrados observou-se que C. flavipes apresentou parasitismo similar nas duas brocas, mas com maior tempo de desenvolvimento e menor viabilidade de casulos em D. flavipennella. Com base nos resultados de comportamento, desenvolvimento e parasitismo de C. flavipes, pode-se concluir que o desempenho de C. flavipesnão foi comprometido em ambas às brocas.

The ecology and evolution of a species is often considered only within the context of pairwise interactions even though a species' distribution and abundance may be determined by interactions with many species within and between trophic levels. Multiple herbivores often share the same host and may interact indirectly by altering the relationships between herbivores, their host plants and their parasitoids. However, the relationships between parasitoids and herbivore hosts have typically been studied in isolation of other herbivore species. I examined how the outcomes of species interactions change when multiple relationships are considered. Chapter 1 examined the potentially conflicting selection pressures Manduca sexta exerts on Nicotiana tabacum (tobacco), since M. sexta has pollinating adults but herbivorous larvae. I demonstrated that high nectar amino acids do not affect floral visitation, but increased oviposition of herbivores on leaves. Thus, the relative costs and benefits of nectar rewards may depend on the community of pollinators and their life histories. In the remaining chapters I examined how feeding on tobacco by the aphid Myzus persicae altered the interactions between a parasitoid (Cotesia congregata) and its hornworm host (M. sexta). Chapter 2 demonstrated that aphids reduced hornworm abundance and parasitism. Changes in hornworm abundance were not due to density-dependent changes in moth oviposition, but the proportion of caterpillars attacked by parasitoids was inversely density dependent with hornworm density. Chapter 3 examined whether changes in hornworm abundance and parasitism reflected aphid-induced changes in host plant quality or volatile emissions. Aphids increased hornworm mortality, did not affect parasitoid performance, and increased parasitoid search time. In combination with Chapter 2, results suggest that aphids can mediate parasitoid-caterpillar interactions through changes in host plants that reduce hornworm survival and alter parasitoid behavior. Chapter 4 addressed how the outcome of interactions that are altered by aphids changed with spatial scale, and found no effect spatial scale on hornworm abundance and parasitism. In this system, aphids alter parasitoid-caterpillar interactions through changes in plant quality that reduce hornworm performance and abundance, and in turn, influence parasitoid attack. This work demonstrates that the outcome of multispecies interactions may not be predictable from pairwise interactions. / Ph. D.

The effects of temperature on emergence, development, oviposition, longevity and fecundity of <i>Cotesia orobenae</i> Forbes (Hymenoptera: Braconidae) were studied. Development time of parasitoid pupae decreased as temperature increased to 35°C. Temperatures between 20 and 25°C were most suitable for parasitoid development, oviposition and fecundity. Longevity was significantly affected by temperature, and was greatest between I5 and 20°C for both sexes. Sex ratios obtained from virgin females, females mated once and females exposed to multiple mating were compared. Virgin females produced only males, those with single or multiple mating produced more females than males. <i>Cotesia orobenae</i> exposed to five densities of third instar cross-striped cabbageworm, <i>Evergestis rimosaiis</i> (Guenee) (Lepidoptera: Pyralidae), for 24 h showed differences in percent parasitization among the treatments. The highest number of parasitoid cocoon masses was obtained from a density of 10 hosts. / Ph. D.

Endoparasitoids of herbivorous lepidopterans have intimate relationships with their host species as well as the plant on which their host develops. Characteristics of both hosts and plants can affect parasitoid success in tri-trophic systems and thus, drive diversification. Genetic differentiation was estimated for Cotesia congregata (Say) collected from two distinct host-plant complexes, Manduca sexta L. on tobacco (Nicotiana tabacum L.) and Ceratomia catalpae, (Haworth) on catalpa (Catalpa bignonioides Walker), in the mid-Atlantic region of North America using seven microsatellite loci and the mitochondrial COI locus. Microsatellite allele frequencies were differentiated based on host-plant complex, and COI haplotypes from individuals on the same host-plant were identical despite geographic distances between catalpa sites of up to 830 km and distances between tobacco sites of up to 294 km. Results indicate genetic differentiation of subpopulations of C. congregata based on host-plant complex and not geographic distance, and were designated as host races. Cotesia congregata is a gregarious parasitoid, meaning that many individuals develop in a single host larva. Superparasitism, or repeated egg-laying events in the same host larva, is likely to occur in gregarious species. Brood size was not a good predictor of superparasitism in C. congregata, but within-brood male allele diversity indicates either superparasitism or multiple mating by female wasps.

A magnitude do problema de Diatraea saccharalis (Fabricius) tem aumentado nos últimos anos, principalmente nas culturas de cana-de-açúcar e milho no Brasil. Tradicionalmente, D. saccharalis tem sido controlado com agentes de controle biológico, principalmente na cultura da cana-de-açúcar. No entanto, a intervenção química tem sido necessária para o controle de D. saccharalis em ambas as culturas. Visando estabelecer estratégias proativas para o manejo da resistência de D. saccharalis a inseticidas e integrar as táticas de controle químico e biológico, objetivou-se nesse trabalho avaliar a toxicidade de alguns inseticidas (triflumuron, lambdacyhalothrin e fipronil) a D. saccharalis e ao parasitóide Cotesia flavipes (Cameron). A caracterização das linhas-básicas de suscetibilidade de D. saccharalis a esses inseticidas foi realizada com bioensaio de ingestão, mediante contaminação da superfície da dieta artificial com o inseticida, utilizando-se lagartas de 2º instar. Baseado nas curvas de concentração-mortalidade da população suscetível de referência, foram definidas as concentrações diagnósticas de 320 µg de triflumuron /mL de água [I.A.(ppm)], 32 µg de fipronil /mL de água, e 3,2 µg de lambdacyhalothrin/ mL de água, correspondentes à CL99, para o monitoramento da resistência Foram verificadas diferenças significativas na suscetibilidade a inseticidas em populações de D. saccharalis coletadas em diferentes regiões produtoras de milho no Brasil e uma no Paraguai. Para triflumuron, as sobrevivências variaram de 0,85 e 34,2%; para fipronil de 0,21 e 2,71%; e para lambda-cyhalothrin de 0,21 a 7,9%. A toxicidade desses inseticidas sobre C. flavipes foi avaliada mediante determinações de efeitos letal e subletal desses inseticidas sobre adultos do parasitóide. Inicialmente foram avaliadas as concentrações recomendadas de 0,08 mg de triflumuron/L de água e 0,075 mg de lambda-cyhalothrin/L de água, além de 10 e 50% da concentração recomendada, mediante bioensaio de contato residual em discos de folha de canade- açúcar de resíduos com 0, 24 e 48 h de idade. A maior toxicidade foi observada com lambdacyhalothrin (mortalidade de até 100%). Triflumuron causou mortalidade de mortalidade de no máximo 32%. Observou-se também uma redução da longevidade de C. flavipes em todas as concentrações e idade de resíduos para ambos inseticidas. Posteriormente, para avaliar os efeitos indiretos de inseticidas sobre C. flavipes, lagartas sobreviventes de D. saccharalis a CL25 de triflumuron, lambda-cyhalothrin e fipronil foram expostas a C. flavipes para parasitismo. A capacidade de parasitismo foi também avaliada para a geração F1 do parasitóide. Nenhum dos inseticidas afetou a emergência de adultos, a mortalidade de larvas e pupas, e a razão sexual do parasitóide. Por outro lado, lambda-cyhalothrin e fipronil afetaram negativamente a taxa instantânea de crescimento de C. flavipes. Portanto, as estratégias de uso destes inseticidas para o controle de D. saccharalis devem ser implementadas com cautela para preservar a vida útil desses importantes inseticidas em programas de manejo integrado de pragas. / The magnitude of Diatraea saccharalis (Fabricius) problem has increased in the past years, mainly in sugarcane and maize crops in Brazil. Traditionally, D. saccharalis has been controlled with biological control agents. However, chemical intervention has been necessary to control D. saccharalis in both crops. For establishing a proactive insecticide resistance management of D. saccharalis and integrating chemical and biological control tactics, the major objective of this work was to evaluate the toxicity of some insecticides (triflumuron, lambdacyhalothrin e fipronil) to D. saccharalis and to the parasitoid Cotesia flavipes (Cameron). The baseline susceptibility of D. saccharalis to these insecticides was characterized with diet surface treatment bioassay by using 2nd instar larvae. Based on concentration-mortality response of the susceptible reference population, diagnostic concentrations of 320 µg of triflumuron/mL of water [A.I. (ppm)], 32 µg of fipronil/mL of water, and 3.2 µg de lambda-cyhalothrin/mL of water, corresponding to LC99, were defined for monitoring resistance. Significant differences in susceptibilities to insecticides were found in populations of D. saccharalis collected from major maize-production regions and one population from Paraguay. For triflumuron, the survivorship varied from 0.8 to 34.2%; for fipronil, from 0.2 to 2.7%; and for lambda-cyhalothrin, from 0.2 to 7.9%. The toxicity of these insecticides to C. flavipes was evaluated by determining the lethal and sublethal effects of the insecticides to the adults of this parasitoid. Initially, commercial rates of 0.08 mg triflumuron/ L of water and 0.075 mg lambda-cyhalothrin / L of water, and 10% and 50% of commercial rates, were evaluated with residual contact bioassay by using sugarcane leaf disks of 0, 24 and 48 h-old residues. The highest toxicity was detected to lambda-cyhalothrin (mortality up to 100%). Triflumuron caused mortality up to 32%. Reduction in the longevity of C. flavipes was detected in all concentrations and residue ages of both insecticides. Then, to evaluate the indirect effect of the insecticides, D. saccharalis larvae that survived at LC25 of triflumuron, lambda-cyhalothrin and fipronil were exposed to C. flavipes. The parasitism capacity of F1 generation of the parasitoid was also evaluated. None of the insecticide affected the adult emergence, pupal and larval mortality, and sexual ratio of the parasitoid. On the other hand, lambda-cyhalothrin e fipronil negatively affect the instantaneous rate of growth of C. flavipes. Therefore, the strategies of the use of these insecticides for controlling D. saccharalis should be carefully designed to preserve their lifetime in integrated pest management programs.

L'hyménoptère Cotesia congregata (Microgastrinae ; Braconidae) pond ses oeufs à l'intérieur de son hôte, la chenille du lépidoptère Manduca sexta (Noctuidae ; Sphingidae) et introduit des particules virales de bracovirus contenant 30 cercles d'ADN double brin. Les gènes viraux portés par ces cercles codent pour une série de protéines qui sont produites dans les tissus de la chenille parasitée. Ces protéines virales jouent un rôle indispensable à la réussite parasitaire. En effet, l'expression des gènes viraux entraîne de nombreuses altérations de la physiologie de l'hôte, notamment un contournement de l'immunité de la chenille qui permet le développement des larves du parasite. D'autre part, le développement de l'hôte est bloqué à un stade pré-pupal. Les travaux portant sur la caractérisation des génomes de bracovirus ont beaucoup progressé et plusieurs familles de gènes ont été découvertes. Une synthèse des connaissances actuelles sur l'immunité des insectes et les gènes de bracovirus potentiellement impliqués dans le contrôle de l'immunité et du développement des lépidoptères est présentée en introduction.<br />Au cours de ma thèse, le séquençage et l'analyse du génome du bracovirus de Cotesia congregata ont été réalisés (Espagne et al 2004). L'existence de plusieurs familles multigéniques a été mise en évidence, notamment la famille des protéines tyrosines phosphatases (PTP) composée de 27 gènes (Provost et al 2004), la famille des cystatines composée de 3 gènes (Espagne et al soumis) et enfin celle des protéines à motif ankyrine composée de 6 gènes (Pennacchio et al en préparation). La caractérisation détaillée de la famille des PTP a été effectuée. La technique d'électrophorèse en champs inversés (FIGE) a permis la localisation physique de ces gènes sur l'ensemble du génome viral, et leur expression a été analysée dans une série de tissus de l'hôte parasité grâce à une méthode de PCR multiplex. Enfin, des tests d'activité biochimique de PTP de bracovirus produites in vitro grâce à un système d'expression en baculovirus.<br />Les gènes des familles décrites sont exprimés dans l'hôte parasité et les protéines possèdent, en général, la fonction biochimique prédite grâce aux domaines conservés qu'elles contiennent. Ceci suggère que ces protéines virales jouent un rôle actif dans les modifications de la physiologie de l'hôte induite par le parasitisme. La caractérisation des gènes viraux exprimés dans l'hôte est une étape indispensable vers l'identification du rôle individuel de chaque protéine dans le contrôle de la physiologie des chenilles parasitées.

Submitted by (edna.saturno@ufrpe.br) on 2016-12-01T14:23:37Z No. of bitstreams: 1 Eliana Maria dos Passos.pdf: 2439142 bytes, checksum: 5cc4ce23eb07068031e4913be088cd08 (MD5) / Made available in DSpace on 2016-12-01T14:23:37Z (GMT). No. of bitstreams: 1 Eliana Maria dos Passos.pdf: 2439142 bytes, checksum: 5cc4ce23eb07068031e4913be088cd08 (MD5) Previous issue date: 2013-02-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Lepidopteran larval parasitism by endoparasitoids is associated with immune suppression and manipulation of the host physiology. This study investigated if the immune response in Diatraea flavipennella (Box) is suppressed by Cotesia flavipes (Cam.) and if changes occur in biochemical profile, haemolymph, and fat body, cytochemistry of hemocytes to ensure parasitism. Levels concentration of nitric oxide, phenoloxidase, and protein was determined. Total number of hemocytes per microliter of hemolymph and the average percentage of these cells were verified. Capacity of melanization and encapsulation by injection and ultrastructural analysis of microbeads was evaluated. Presence of apoptotic cells in fat body was investigated using TUNEL technique. Levels of carbohydrate, lipid, and protein in hemolymph and fat body were quantified, as well as the proteic profile of hemolymph was characterized. Histological sections of stained caterpillars were obtained using PAS (Periodic acid/Schiff's) reaction. Marking of acidic polysaccharides, mucin, and lipids was investigated on hemocytes. Results showed reduction in nitric oxide production, phenol oxidase activity, and total number of hemocytes. In the differential count, increase in number of plasmatocytes and reduction of spherulocytes were observed. The encapsulation capacity was affected. Apoptosis in hemocytes and fat body was registered. Reduction of proteins and lipids occurred in hemolymph and protein; reduction of carbohydrate occurred in body fat. Cytochemistry of hemocytes was changed, reducing the acidic polysaccharides in prohemocytes and oenocytoids, mucin in plasmatocytes and granulocytes, and lipids in adipohemocytes, granulocytes, and prohemocytes. It was also observed a drastic body fat degeneration. The proteic profile showed presence of four specific proteins of parasitism in the hemolymph. It is concluded that C. flavipes is effective for controlling D. flavipennella by suppressing the immune, humoral, and cellular response, altering the biochemical profile of hemolymph, fat body, and cytochemistry of hemocytes. / As espécies Diatraea saccharalis (Fabr.) e Diatraea flavipennella (Box) representam um problema para cultura da cana-de-açúcar, sendo o endoparasitoide Cotesia flavipes (Cam.) introduzido em 1974 para o controle destas pragas. Nos últimos 30 anos houve inversão na população destas espécies de brocas no estado de Alagoas e hoje há predominância de D. flavipennella nos canaviais nordestinos, surgindo entre os produtores à idéia de que C. flavipes não controla satisfatoriamente esta praga. Como o parasitismo de larvas de lepidópteros por endoparasitoides esta associada com a supressão da imunidade e manipulação da fisiologia, do hospedeiro, para aumentar a disponibilidade de nutrientes. Neste trabalho investigou se a resposta imune (níveis de óxido nítrico, atividade da fenoloxidase, contagem total e diferencial dos hemócitos, capacidade de encapsulação e apoptose) em D. flavipennella seria suprimida por C. flavipes e se alterações no perfil bioquímico, da hemolinfa e do corpo gorduroso (proteínas, carboidratos e lipídeos), bem como modificações na citoquímica dos hemócitos, ocorreriam para garantir o parasitismo. Os resultados mostraram redução na produção de óxido nítrico, na atividade da fenoloxidase e no número total de hemócitos. Na contagem diferencial, observou-se aumento no número de plasmatócitos e redução de esferulócitos. A capacidade de encapsulação foi afetada. Registrou-se apoptose nos hemócitos e corpo gorduroso. Ocorreu redução de proteínas e lipídeos na hemolinfa e proteína e carboidrato no corpo gorduroso. A citoquímica dos hemócitos foi alterada, tendo reduzido polissacarídeos ácidos nos prohemócitos e oenocitóides, mucina nos plasmatócitos e granulócitos e lipídeos nos adipohemócitos, granulócitos, e prohemócitos. Observou-se também uma drástica degeneração do corpo gorduroso. Já o perfil protéico revelou a presença de quatro proteínas específicas do parasitismo na hemolinfa. Conclui-se, então, que C. flavipes é eficiente no controle de D. flavipennella por suprimir a resposta imunológica, humoral e celular, alterar o perfil bioquímico da hemolinfa e corpo gorduroso e citoquímica dos hemócitos.

A magnitude do problema de Diatraea saccharalis (Fabricius) tem aumentado nos últimos anos, principalmente nas culturas de cana-de-açúcar e milho no Brasil. Tradicionalmente, D. saccharalis tem sido controlado com agentes de controle biológico, principalmente na cultura da cana-de-açúcar. No entanto, a intervenção química tem sido necessária para o controle de D. saccharalis em ambas as culturas. Visando estabelecer estratégias proativas para o manejo da resistência de D. saccharalis a inseticidas e integrar as táticas de controle químico e biológico, objetivou-se nesse trabalho avaliar a toxicidade de alguns inseticidas (triflumuron, lambdacyhalothrin e fipronil) a D. saccharalis e ao parasitóide Cotesia flavipes (Cameron). A caracterização das linhas-básicas de suscetibilidade de D. saccharalis a esses inseticidas foi realizada com bioensaio de ingestão, mediante contaminação da superfície da dieta artificial com o inseticida, utilizando-se lagartas de 2º instar. Baseado nas curvas de concentração-mortalidade da população suscetível de referência, foram definidas as concentrações diagnósticas de 320 µg de triflumuron /mL de água [I.A.(ppm)], 32 µg de fipronil /mL de água, e 3,2 µg de lambdacyhalothrin/ mL de água, correspondentes à CL99, para o monitoramento da resistência Foram verificadas diferenças significativas na suscetibilidade a inseticidas em populações de D. saccharalis coletadas em diferentes regiões produtoras de milho no Brasil e uma no Paraguai. Para triflumuron, as sobrevivências variaram de 0,85 e 34,2%; para fipronil de 0,21 e 2,71%; e para lambda-cyhalothrin de 0,21 a 7,9%. A toxicidade desses inseticidas sobre C. flavipes foi avaliada mediante determinações de efeitos letal e subletal desses inseticidas sobre adultos do parasitóide. Inicialmente foram avaliadas as concentrações recomendadas de 0,08 mg de triflumuron/L de água e 0,075 mg de lambda-cyhalothrin/L de água, além de 10 e 50% da concentração recomendada, mediante bioensaio de contato residual em discos de folha de canade- açúcar de resíduos com 0, 24 e 48 h de idade. A maior toxicidade foi observada com lambdacyhalothrin (mortalidade de até 100%). Triflumuron causou mortalidade de mortalidade de no máximo 32%. Observou-se também uma redução da longevidade de C. flavipes em todas as concentrações e idade de resíduos para ambos inseticidas. Posteriormente, para avaliar os efeitos indiretos de inseticidas sobre C. flavipes, lagartas sobreviventes de D. saccharalis a CL25 de triflumuron, lambda-cyhalothrin e fipronil foram expostas a C. flavipes para parasitismo. A capacidade de parasitismo foi também avaliada para a geração F1 do parasitóide. Nenhum dos inseticidas afetou a emergência de adultos, a mortalidade de larvas e pupas, e a razão sexual do parasitóide. Por outro lado, lambda-cyhalothrin e fipronil afetaram negativamente a taxa instantânea de crescimento de C. flavipes. Portanto, as estratégias de uso destes inseticidas para o controle de D. saccharalis devem ser implementadas com cautela para preservar a vida útil desses importantes inseticidas em programas de manejo integrado de pragas. / The magnitude of Diatraea saccharalis (Fabricius) problem has increased in the past years, mainly in sugarcane and maize crops in Brazil. Traditionally, D. saccharalis has been controlled with biological control agents. However, chemical intervention has been necessary to control D. saccharalis in both crops. For establishing a proactive insecticide resistance management of D. saccharalis and integrating chemical and biological control tactics, the major objective of this work was to evaluate the toxicity of some insecticides (triflumuron, lambdacyhalothrin e fipronil) to D. saccharalis and to the parasitoid Cotesia flavipes (Cameron). The baseline susceptibility of D. saccharalis to these insecticides was characterized with diet surface treatment bioassay by using 2nd instar larvae. Based on concentration-mortality response of the susceptible reference population, diagnostic concentrations of 320 µg of triflumuron/mL of water [A.I. (ppm)], 32 µg of fipronil/mL of water, and 3.2 µg de lambda-cyhalothrin/mL of water, corresponding to LC99, were defined for monitoring resistance. Significant differences in susceptibilities to insecticides were found in populations of D. saccharalis collected from major maize-production regions and one population from Paraguay. For triflumuron, the survivorship varied from 0.8 to 34.2%; for fipronil, from 0.2 to 2.7%; and for lambda-cyhalothrin, from 0.2 to 7.9%. The toxicity of these insecticides to C. flavipes was evaluated by determining the lethal and sublethal effects of the insecticides to the adults of this parasitoid. Initially, commercial rates of 0.08 mg triflumuron/ L of water and 0.075 mg lambda-cyhalothrin / L of water, and 10% and 50% of commercial rates, were evaluated with residual contact bioassay by using sugarcane leaf disks of 0, 24 and 48 h-old residues. The highest toxicity was detected to lambda-cyhalothrin (mortality up to 100%). Triflumuron caused mortality up to 32%. Reduction in the longevity of C. flavipes was detected in all concentrations and residue ages of both insecticides. Then, to evaluate the indirect effect of the insecticides, D. saccharalis larvae that survived at LC25 of triflumuron, lambda-cyhalothrin and fipronil were exposed to C. flavipes. The parasitism capacity of F1 generation of the parasitoid was also evaluated. None of the insecticide affected the adult emergence, pupal and larval mortality, and sexual ratio of the parasitoid. On the other hand, lambda-cyhalothrin e fipronil negatively affect the instantaneous rate of growth of C. flavipes. Therefore, the strategies of the use of these insecticides for controlling D. saccharalis should be carefully designed to preserve their lifetime in integrated pest management programs.

L'espèce Plutella xylostella (L.) (Lepidoptera : Plutellidae) défoliatrice des choux constitue surtout un problème dans les régions tropicales et subtropicales. La lutte chimique a rapidement montré ses limites du fait de l'apparition de résistance dans les populations. Des moyens de lutte alternatifs ont été mis en place, impliquant principalement des insectes parasitoïdes, parmi lesquels Oomyzus sokolowskii (Kurdjumov) (Hymenoptera : Eulophidae) et Cotesia vestalis (Haliday) (Hymenoptera : Braconidae) qui sont les plus couramment utilisés en raison de leur spécificité envers P. xylostella. Afin de contribuer à une meilleure connaissance du contrôle de la teigne en région tropicale, nous avons étudié les relations hôteparasitoïde entre P. xylostella et O. sokolowskii d'une part, et P. xylostella et C. vestalis d'autre part, en conditions de laboratoire et sur le terrain au Sénégal et au Bénin. Au Sénégal, quatre espèces de parasitoïdes sont présentes sur les chenilles : O. sokolowskii, Apanteles litae, C. vestalis et Brachymeria citrae. Au Bénin, seule l'espèce C. vestalis est présente. Au Sénégal comme au Bénin, les facteurs climatiques contribuent au développement de la teigne et les précipitations ne régulent pas les populations du ravageur. Dans ces deux pays, la teigne n'est pas contrôlée par ses ennemis naturels. La lutte biologique par conservation y est à prendre en considération et l'utilisation de plantes compagnes cultivées en association avec le chou peut être envisagée pour réduire les populations de la teigne. Les études en laboratoire ont montré qu'Oomyzus sokolowskii est un parasitoïde larvo-nymphal performant. ConcernantC. vestalis, les femelles détectent et reconnaissent leur hôte grâce aux lipides cuticulaires émis par les chenilles. Des marqueurs moléculaires (isozymes et ISSR) ont confirmé une forte variabilité entre les populations de P. xylostella à l'échelle mondiale, les populations d'Australie et du Japon étant très différentes des autres et formant deux groupes distincts. La structuration des populations semble influencée par le type de climat : tropical et non tropical.