No description available.

This study investigated effects of plant quality and natural enemies on the abundance and survivorship of several leaf miner species on Florida scrub oaks over several ecological scales. Three oak species (Quercus laevis, Q. geminata, and Q. myrtifolia) and four leafminer species (Acrocercops albinatella, Brachys tesselatus, Stilbosis quadripustulatus, and Cameraria sp. nova) were the main focus of five separate studies, addressing effects of bottom-up and top-down factors at regional, local, and individual scales. At the regional scale, it was observed that Cameraria sp. nova was aggregated into sites, and sites closer to each other exhibited similar densities of mines than sites farther apart. None of the bottom-up and top-down factors studied were spatially structured, but did influence the variation in Cameraria abundance over the range of the host plant Q. myrtifolia. At the local scale, all leaf miners studied were aggregated between and within plants, and variation in bottom-up factors among individual plants explained variation in abundance for some of the leaf miners studied. Intra-specific competition was identified as an important factor influencing mine survivorship, but inter-specific competition among leaf miners and gall-formers did not shape the community structure of oak herbivores. Experimental manipulation of bottom-up and top-down factors via fertilization and natural enemy removal showed that bottom-up effects were important determinants of leaf miner abundance, as fertilized plants supported 2 to 5-fold more herbivores than control plants. The removal of natural enemies, on the other hand, did not significantly impact the abundance and/or the survivorship of leaf miners and other guilds studied. At individual scales, it was demonstrated that two leaf miner species responded to random variations in leaf morphology, by increasing in abundance in individual host plants with more asymmetric leaves and/or higher levels of fluctuating as ymmetry. These results offered support for the plant stress hypothesis and differences in host plant quality were again partially responsible for the results found.

Made available in DSpace on 2014-06-11T19:32:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-27Bitstream added on 2014-06-13T20:22:57Z : No. of bitstreams: 1 silva_rj_dr_jabo.pdf: 999654 bytes, checksum: 9b9706815aad595ba6fd6e0dea74a998 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O parasitoide Diaeretiella rapae (McIntosh) é considerado um importante inimigo natural de pulgões em culturas de brassicáceas, apresentando potencial como agente de controle biológico desses insetos-praga. O presente estudo visou obter informações sobre D. rapae para subsidiar o desenvolvimento de programas de controle biológico de pulgões em cultivos de brassicáceas. Foram considerados os seguintes objetivos específicos: a) avaliar a qualidade hospedeira de Myzus persicae (Sulzer), Lipaphis erysimi (Kaltenbach) e Brevicoryne brassicae (L.); b) determinar as exigências térmicas; c) determinar as tabelas de vida de fertilidade em diferentes temperaturas e d) avaliar o efeito do armazenamento à baixa temperatura. Para condução dos experimentos e criação das espécies de pulgões e parasitoide utilizaram-se plantas de couve-manteiga (Brassica oleracea var. acephala) Da Geórgia. A qualidade hospedeira foi investigada utilizando-se câmara climatizada regulada a 25 ± 1ºC, 60 ± 10% UR e 12 horas de fotofase e considerando-se as seguintes variáveis biológicas de D. rapae: parasitismo, períodos de desenvolvimento, porcentagem de emergência de adultos, razão sexual, longevidade e tamanho. As exigências térmicas e tabelas de vida de fertilidade foram determinadas em câmaras climatizadas reguladas a 15, 20, 25 e 30 ± 1 ºC, 60 ± 10% UR e 12 horas de fotofase. Para o armazenamento à baixa temperatura utilizou-se câmara climatizada sob temperatura constante de 5 ± 1°C nos seguintes períodos: 0, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 34 e 36 dias. Entre as espécies de pulgões estudadas M. persicae foi a que proporcionou maior qualidade a D. rapae. O limite térmico inferior de desenvolvimento (Tb) e a constante térmica (K) do parasitoide foram 4,0°C e 245,3 GD, respectivamente. A temperatura afetou o desempenho reprodutivo de D. rapae, sendo 25°C... / The parasitoid Diaeretiella rapae (McIntosh) is considered an important natural enemy of aphids in Brassicaceae, showing potential as a biological control agent of insect pests. This study aimed at obtaining information about D. rapae to subsidize the development of programs for biological control of aphids in Brassicaceae. Were considered the following specific objectives: a) to assess the host quality Myzus persicae (Sulzer), Lipaphis erysimi (Kaltenbach) and Brevicoryne brassicae (L.), b) to determine the thermal requirements, c) to determine the fertility life tables at different temperatures and d) to evaluate the effect of storage at low temperature. The experiments and rearing of parasitoid and aphid species were conducted using cabbage plants (Brassica oleracea var. acephala) Da Geórgia. The host quality was investigated using climate chamber at 25 ± 1 º C, 60 ± 10% RH and 12 h photophase and considering the following biological variables of D. rapae: parasitism, developmental periods, percentage of adult emergence, sex ratio, longevity and size. The thermal requirements and fertility life tables were determined in climatic chambers at 15, 20, 25 and 30 ± 1 º C, 60 ± 10% RH and 12 hours photophase. The storage at low temperature was determined under constant temperature of 5 ± 1 ° C in the following periods: 0, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 34 and 36 days. Among the aphid species studied M. persicae showed high quality to D. rapae. The lower thermal threshold (Tb) and thermal constant (K) of the parasitoid were 4.0 °C and 245.3 GD, respectively. The temperature affected the reproductive performance of D. rapae, 25 ° C provided the best thermal conditions for the population growth of the specie. The storage of D. rapae at 5 °C for up to 32 days does not negatively affect the emergence and survival. The storage up to 36 days did not influence... (Complete abstract click electronic access below)

Orientador: Francisco Jorge Cividanes / Banca: Sergio Antonio De Bortoli / Banca: Nelson Wanderley Perioto / Banca: José Roberto Postali Parra / Banca: Marcus Vinicius Sampaio / Resumo: O parasitoide Diaeretiella rapae (McIntosh) é considerado um importante inimigo natural de pulgões em culturas de brassicáceas, apresentando potencial como agente de controle biológico desses insetos-praga. O presente estudo visou obter informações sobre D. rapae para subsidiar o desenvolvimento de programas de controle biológico de pulgões em cultivos de brassicáceas. Foram considerados os seguintes objetivos específicos: a) avaliar a qualidade hospedeira de Myzus persicae (Sulzer), Lipaphis erysimi (Kaltenbach) e Brevicoryne brassicae (L.); b) determinar as exigências térmicas; c) determinar as tabelas de vida de fertilidade em diferentes temperaturas e d) avaliar o efeito do armazenamento à baixa temperatura. Para condução dos experimentos e criação das espécies de pulgões e parasitoide utilizaram-se plantas de couve-manteiga (Brassica oleracea var. acephala) Da Geórgia. A qualidade hospedeira foi investigada utilizando-se câmara climatizada regulada a 25 ± 1ºC, 60 ± 10% UR e 12 horas de fotofase e considerando-se as seguintes variáveis biológicas de D. rapae: parasitismo, períodos de desenvolvimento, porcentagem de emergência de adultos, razão sexual, longevidade e tamanho. As exigências térmicas e tabelas de vida de fertilidade foram determinadas em câmaras climatizadas reguladas a 15, 20, 25 e 30 ± 1 ºC, 60 ± 10% UR e 12 horas de fotofase. Para o armazenamento à baixa temperatura utilizou-se câmara climatizada sob temperatura constante de 5 ± 1°C nos seguintes períodos: 0, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 34 e 36 dias. Entre as espécies de pulgões estudadas M. persicae foi a que proporcionou maior qualidade a D. rapae. O limite térmico inferior de desenvolvimento (Tb) e a constante térmica (K) do parasitoide foram 4,0°C e 245,3 GD, respectivamente. A temperatura afetou o desempenho reprodutivo de D. rapae, sendo 25°C... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The parasitoid Diaeretiella rapae (McIntosh) is considered an important natural enemy of aphids in Brassicaceae, showing potential as a biological control agent of insect pests. This study aimed at obtaining information about D. rapae to subsidize the development of programs for biological control of aphids in Brassicaceae. Were considered the following specific objectives: a) to assess the host quality Myzus persicae (Sulzer), Lipaphis erysimi (Kaltenbach) and Brevicoryne brassicae (L.), b) to determine the thermal requirements, c) to determine the fertility life tables at different temperatures and d) to evaluate the effect of storage at low temperature. The experiments and rearing of parasitoid and aphid species were conducted using cabbage plants (Brassica oleracea var. acephala) Da Geórgia. The host quality was investigated using climate chamber at 25 ± 1 º C, 60 ± 10% RH and 12 h photophase and considering the following biological variables of D. rapae: parasitism, developmental periods, percentage of adult emergence, sex ratio, longevity and size. The thermal requirements and fertility life tables were determined in climatic chambers at 15, 20, 25 and 30 ± 1 º C, 60 ± 10% RH and 12 hours photophase. The storage at low temperature was determined under constant temperature of 5 ± 1 ° C in the following periods: 0, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 34 and 36 days. Among the aphid species studied M. persicae showed high quality to D. rapae. The lower thermal threshold (Tb) and thermal constant (K) of the parasitoid were 4.0 °C and 245.3 GD, respectively. The temperature affected the reproductive performance of D. rapae, 25 ° C provided the best thermal conditions for the population growth of the specie. The storage of D. rapae at 5 °C for up to 32 days does not negatively affect the emergence and survival. The storage up to 36 days did not influence... (Complete abstract click electronic access below) / Doutor

I used a theoretical model to determine the conditions under which Cactoblastis cactorum populations would be expected to experience positive population growth. Results from simulations suggest that host species richness, host quality, and the C. cactorum death rate interact to determine the probability of C. cactorum positive population growth. I also studied the influence of host diversity empirically. Cactoblastis cactorum prevalence was significantly higher when O. stricta was present in the community. Also, higher species richness within host assemblages led to a higher prevalence of infestation than in single-species host assemblages. Finally, I explored cooccurrence patterns of native cactuseeding insects in an effort to document the impact of C. cactorum to native insect assemblages. The presence of C. cactorum in a community did not appear to affect the structure of native cactuseeding insect assemblages.

No description available.

Cette étude porte sur l’écologie saisonnière des parasitoïdes des œufs de l’arpenteuse de la pruche (Lepidoptera : Geometridae), un important défoliateur du Québec (Canada). Premièrement, nous décrivons les patrons saisonniers de parasitisme d’hôtes sentinelles par Telenomus coloradensis, T. droozi, T. flavotibiae (Hymenoptera : Scelionidae), et Trichogramma spp., dans la région du Bas-Saint-Laurent. Telenomus flavotibiae et Trichogramma spp. parasitent rarement les œufs de l’arpenteuse de la pruche alors que T. coloradensis et T. droozi sont très abondants au printemps. En laboratoire, la convenance des hôtes pour T. coloradensis diminue rapidement avec leur développement embryonnaire au printemps, affectant négativement les niveaux de parasitisme, ainsi que la survie, la taille, le temps de développement et la longévité de la progéniture. Telenomus coloradensis et T. droozi sont actifs très tôt en saison, alors que les températures sont froides (4°C) pour profiter du développement embryonnaire peu avancé de l’hôte. À partir de paramètres empiriques, nous estimons que la progéniture de T. coloradensis issue du parasitisme printanier émerge au milieu de l’été, alors que l’hôte est totalement absent de l’environnement forestier. La nouvelle génération de femelles serait donc susceptible d’entrer précocement en diapause reproductive. D’ailleurs, nos résultats de laboratoire démontrent qu’une période de privation d’hôtes affecte négativement l’activité parasitaire de T. coloradensis. Ce phénomène pourrait expliquer les niveaux très faibles de parasitisme des œufs de l’arpenteuse de la pruche à l’automne. Étonnamment toutefois, les hôtes en début de diapause (à l’automne) sont de meilleure qualité énergétique que les hôtes en post-diapause (au printemps). Alors que des études précédentes ont démontré que T. coloradensis peut survivre à l’hiver en tant qu’immature à l’intérieur des hôtes, nos résultats indiquent que ce sont principalement les femelles fertilisés qui passent l’hiver en diapause reproductive, avec un point de surfusion automnal moyen de -30,6°C. / This study focuses on the seasonal ecology of egg parasitoids of the hemlock looper (Lepidoptera: Geometridae), a major forest defoliator in the province of Quebec (Canada). At first, we describe the seasonal occurrence of parasitism in sentinel hosts by Telenomus coloradensis, T. droozi, T. flavotibiae (Hymenoptera: Scelionidae) and Trichogramma spp., in the Lower St.Lawrence region. Telenomus flavotibiae and Trichogramma spp. rarely parasitize eggs of the hemlock looper, while T. coloradensis and T. droozi are very abundant in spring. In the laboratory, the host suitability for T. coloradensis decreases rapidly with their embryonic development in spring, affecting negatively the levels of parasitism, as well as the survival, size, development time and longevity of offspring. Accordingly, female T. coloradensis and T. droozi are active very early in season, when temperature is cold (4° C), presumably to benefit from low embryonic development of the host. From developmental parameters measured in the laboratory, we estimate that the spring progeny of T. coloradensis emerges in mid-summer, when eggs of the hemlock looper are totally absent from the forest environment. The new generation of female parasitoids is thus expected to enter in a early reproductive diapause : our laboratory results show that an extended host deprivation period negatively affects parasitism by T. coloradensis. This may contribute to explain the very low levels of parasitism of hemlock looper eggs in fall. Our laboratory tests also show that unfertilized eggs in the fall do not allow the development of T. coloradensis. Surprisingly, however, host eggs in early-diapause (in autumn) are energically more suitable than hosts in post-diapause (in spring). While previous studies have shown that T. coloradensis may overwinter as immature eggs inside the host, our field and laboratory results indicate that it is mainly the fertilized females of this species that overwinter in reproductive diapause, with a supercooling point of -30.6 °C in fall.

Cette étude porte sur l’écologie saisonnière des parasitoïdes des œufs de l’arpenteuse de la pruche (Lepidoptera : Geometridae), un important défoliateur du Québec (Canada). Premièrement, nous décrivons les patrons saisonniers de parasitisme d’hôtes sentinelles par Telenomus coloradensis, T. droozi, T. flavotibiae (Hymenoptera : Scelionidae), et Trichogramma spp., dans la région du Bas-Saint-Laurent. Telenomus flavotibiae et Trichogramma spp. parasitent rarement les œufs de l’arpenteuse de la pruche alors que T. coloradensis et T. droozi sont très abondants au printemps. En laboratoire, la convenance des hôtes pour T. coloradensis diminue rapidement avec leur développement embryonnaire au printemps, affectant négativement les niveaux de parasitisme, ainsi que la survie, la taille, le temps de développement et la longévité de la progéniture. Telenomus coloradensis et T. droozi sont actifs très tôt en saison, alors que les températures sont froides (4°C) pour profiter du développement embryonnaire peu avancé de l’hôte. À partir de paramètres empiriques, nous estimons que la progéniture de T. coloradensis issue du parasitisme printanier émerge au milieu de l’été, alors que l’hôte est totalement absent de l’environnement forestier. La nouvelle génération de femelles serait donc susceptible d’entrer précocement en diapause reproductive. D’ailleurs, nos résultats de laboratoire démontrent qu’une période de privation d’hôtes affecte négativement l’activité parasitaire de T. coloradensis. Ce phénomène pourrait expliquer les niveaux très faibles de parasitisme des œufs de l’arpenteuse de la pruche à l’automne. Étonnamment toutefois, les hôtes en début de diapause (à l’automne) sont de meilleure qualité énergétique que les hôtes en post-diapause (au printemps). Alors que des études précédentes ont démontré que T. coloradensis peut survivre à l’hiver en tant qu’immature à l’intérieur des hôtes, nos résultats indiquent que ce sont principalement les femelles fertilisés qui passent l’hiver en diapause reproductive, avec un point de surfusion automnal moyen de -30,6°C. / This study focuses on the seasonal ecology of egg parasitoids of the hemlock looper (Lepidoptera: Geometridae), a major forest defoliator in the province of Quebec (Canada). At first, we describe the seasonal occurrence of parasitism in sentinel hosts by Telenomus coloradensis, T. droozi, T. flavotibiae (Hymenoptera: Scelionidae) and Trichogramma spp., in the Lower St.Lawrence region. Telenomus flavotibiae and Trichogramma spp. rarely parasitize eggs of the hemlock looper, while T. coloradensis and T. droozi are very abundant in spring. In the laboratory, the host suitability for T. coloradensis decreases rapidly with their embryonic development in spring, affecting negatively the levels of parasitism, as well as the survival, size, development time and longevity of offspring. Accordingly, female T. coloradensis and T. droozi are active very early in season, when temperature is cold (4° C), presumably to benefit from low embryonic development of the host. From developmental parameters measured in the laboratory, we estimate that the spring progeny of T. coloradensis emerges in mid-summer, when eggs of the hemlock looper are totally absent from the forest environment. The new generation of female parasitoids is thus expected to enter in a early reproductive diapause : our laboratory results show that an extended host deprivation period negatively affects parasitism by T. coloradensis. This may contribute to explain the very low levels of parasitism of hemlock looper eggs in fall. Our laboratory tests also show that unfertilized eggs in the fall do not allow the development of T. coloradensis. Surprisingly, however, host eggs in early-diapause (in autumn) are energically more suitable than hosts in post-diapause (in spring). While previous studies have shown that T. coloradensis may overwinter as immature eggs inside the host, our field and laboratory results indicate that it is mainly the fertilized females of this species that overwinter in reproductive diapause, with a supercooling point of -30.6 °C in fall.