A catalog of the Coleoptera of America north of Mexico family : Cupesidae /

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Phylogeography of the scarab beetle Antitrogus parvulus Britton (Coleoptera : Scarabaeidae) in south-eastern Queensland, Australia

This study surveys the population genetic structure of Childers canegrub, Antitrogus parvulus, to elucidate its population dynamics and gene flow. Antitrogus parvulus is a pest of sugarcane in the Bundaberg region and this knowledge can be used to optimise integrated pest management practices. Here, base-pair differences in the cytochrome oxidase II gene (COII) were used to characterise haplotypic diversity, infer levels of gene flow, and phylogenetic relationships of alleles and their phylogeographical structure. There were 28 unique haplotypes among the 70 sequenced individuals from the seven locations. All three variance components (among regions, among populations, within populations) are highly significant, with highest genetic diversity among regions and lowest among populations within regions. A positive correlation between migration rates and geographical distance and significant phylogeographical structure between four main geographical regions. The main implication of these findings for pest management is that if a grower can eliminate an existing infestation within a field, then reinvasion will be slow and further outbreaks within that field are unlikely to occur. The low dispersal ability of females also means that any resistance to insecticides that develops is likely to remain localised, but will rapidly become dominant within the affected population.

Evaluation of different models to describe egg and pupal development of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka

Abstract Development data of eggs and pupae of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka, at constant temperatures were used to evaluate a linear and seven nonlinear models for insect development. Model evaluation was based on fit to data (residual sum of squares and coefficient of determination or coefficient of nonlinear regression), number of measurable parameters, the biological value of the fitted coefficients and accuracy in the estimation of thresholds. Of the nonlinear models, the Lactin model fitted experimental data well and along with the linear model, can be used to describe the temperature-dependent development of this species.

Ecological genetics of Melaleuca quinquenervia (Myrtaceae): Population variation in Florida and its influence on performance of the biological control agent Oxyops vitiosa (Coleoptera: Curculionidae)

Melaleuca quinquenervia (Cav.) Blake (Myrtaceae) was imported into Florida from Australia over a century ago as a landscape plant. A favorable climate and periodic wildfires helped M. quinquenervia thrive; it now occupies about 200,000 hectares in southern Florida. A biological control (i.e., biocontrol) program against M. quinquenervia has been initiated, but not all biocontrol releases are successful. Some scientists have argued that poor biocontrol agent success may relate to genetic differences among populations of invasive weeds. I tested this premise by determining (1) the number and origins of M. quinquenervia introductions into Florida, (2) whether multiple introduction events resulted in the partitioning of Florida's M. quinquenervia populations into discrete biotypes, and (3) whether Oxyops vitiosa, an Australia snout beetle imported to control this weed, might discriminate among putative M. quinquenervia biotypes. Careful scrutiny of early horticultural catalogs and USDA plant introduction records suggested at least six distinct introduction events. Allozyme analyses indicated that the pattern of these introductions, and the subsequent redistribution of progeny, has resulted in geographic structuring of the populations in southern Florida. For example, trees on Florida's Gulf Coast had a greater effective number of alleles and exhibited greater heterozygosity than trees on the Atlantic Coast. Essential oil yields from M. quinquenervia leaves followed a similar trend; Gulf Coast trees yielded nearly twice as much oil as Atlantic Coast trees when both were grown in a common garden. These differences were partially explained by the predominance of a chemical phenotype (chemotype) very rich in the sesquiterpene (E)-nerolidol in M. quinquenervia trees from the Gulf Coast, but rich in a mixture of the monoterpene 1,8-cineole and the sesquiterpene viridiflorol in trees from the Atlantic Coast. Performance of O. vitiosa differed dramatically in laboratory studies depending on the chemotype of the foliage they were fed. Larval survivorship was four-fold greater on the (E)-nerolidol chemotype. Growth was also greater, with adult O. vitiosa gaining nearly 50% more biomass on the (E)-nerolidol plants than on the second chemotype. The results of this study thus confirmed the premise that plant genotype can affect the population dynamics of insects released as weed biocontrols. ^

Causas e consequências da onivoria de peixes em ecossistemas aquáticos

Omnivory is a predominant feeding strategy among tropical fishes, but knowledge about its causes and consequences of this pattern is scarce. In this study we hypothesized that tropical fish feed lower in food web as a way to compensate a higher energetic demand, which increases with increasing water temperature and body size. Information about 8172 freshwater and marine fish species from whole world, from tropical and temperate ecosystems, showed that the trophic position of non-carnivore fish decreases with increasing body size in tropical but not in temperate ecosystems. This result indicates that the higher energetic demand of large-bodied tropical fish should exert a selective force in favor of omnivory. As a consequence, trophic dynamics in tropical freshwater ecosystems should have different patterns comparing to temperate ones, with major implications for water management and restoration of eutrophic aquatic ecosystems. Another hypothesis of this work was that effects of tropical omnivorous planktivorous fish on planktonic communities depend of primary producers stoichiometric composition, which depends of light availability relative to nutrients ratios. A mesocosm experiment, manipulating light availability and planktivorous fish presence, confirmed our hypothesis indicating that resource stoichiometric composition (consequently nutritional quality), determine trophic structure of pelagic food webs in tropical lakes. Finally another mesocosm experiment indicated that the removal of omnivorous benthivorous fish should be more efficient than removal of omnivorous planktivorus fish, as a way to improve water quality in tropical lakes and reservoirs. This last experiment showed that omnivorous planktivorous fish increase phytoplankton biomass due to trophic cascade interactions, without increasing nutrient concentrations in the water column. On the other hand, omnivorous benthivorous fish, feeding on detritus and other benthonic food sources and excreting nutrients in the water column, are responsible for translocate nutrient from sediments to the water column, increasing phosphorus pool and phytoplankton biomass. Thereby, internal phosphorus supply should be reduced and water quality of eutrophicated lakes could be improved by removing omnivorous benthivorous fish.

Causas e consequências da onivoria de peixes em ecossistemas aquáticos

Omnivory is a predominant feeding strategy among tropical fishes, but knowledge about its causes and consequences of this pattern is scarce. In this study we hypothesized that tropical fish feed lower in food web as a way to compensate a higher energetic demand, which increases with increasing water temperature and body size. Information about 8172 freshwater and marine fish species from whole world, from tropical and temperate ecosystems, showed that the trophic position of non-carnivore fish decreases with increasing body size in tropical but not in temperate ecosystems. This result indicates that the higher energetic demand of large-bodied tropical fish should exert a selective force in favor of omnivory. As a consequence, trophic dynamics in tropical freshwater ecosystems should have different patterns comparing to temperate ones, with major implications for water management and restoration of eutrophic aquatic ecosystems. Another hypothesis of this work was that effects of tropical omnivorous planktivorous fish on planktonic communities depend of primary producers stoichiometric composition, which depends of light availability relative to nutrients ratios. A mesocosm experiment, manipulating light availability and planktivorous fish presence, confirmed our hypothesis indicating that resource stoichiometric composition (consequently nutritional quality), determine trophic structure of pelagic food webs in tropical lakes. Finally another mesocosm experiment indicated that the removal of omnivorous benthivorous fish should be more efficient than removal of omnivorous planktivorus fish, as a way to improve water quality in tropical lakes and reservoirs. This last experiment showed that omnivorous planktivorous fish increase phytoplankton biomass due to trophic cascade interactions, without increasing nutrient concentrations in the water column. On the other hand, omnivorous benthivorous fish, feeding on detritus and other benthonic food sources and excreting nutrients in the water column, are responsible for translocate nutrient from sediments to the water column, increasing phosphorus pool and phytoplankton biomass. Thereby, internal phosphorus supply should be reduced and water quality of eutrophicated lakes could be improved by removing omnivorous benthivorous fish.

Estudo da distribuição de metais em água, sedimento e organismos aquáticos de rios e reservatórios pertencentes à rede de monitoramento da qualidade dos sedimentos do estado de São Paulo, Brasil

Dissertação (Mestrado)

Invertebrados aquáticos no detrito de Salvinia herzogii de la Sota em lagos rasos do sul do Brasil

A colonização por invertebrados aquáticos no detrito de Salvinia herzogii foi estudada em dois lagos rasos subtropicais de diferentes estados tróficos (eutrófico e oligotrófico) localizados no campus Carreiros da Universidade Federal do Rio Grande, extremo sul do Brasil. Aproximadamente 6g (peso úmido) de S. herzogii foram incubados em experimentos com litter bags (30 X 20 cm com 10 mm de malha) e a decomposição do detrito acompanhada durante 110 dias (entre setembro de 2008 e janeiro de 2009), período no qual o detrito decompôs-se cerca de 95%. Quatro réplicas foram retiradas após os intervalos de 1, 30, 60, 90 e 110 dias de incubação e o detrito foi limpo em água corrente sob peneira de 250µm de malha para que fossem retidos os organismos e depois fixados em álcool 80%. As plantas depois de limpas foram secas à 60ºC por 72 horas para obtenção do peso seco, depois trituradas, para as análises de nitrogênio e fósforo total e para obtenção do peso seco livre de cinzas, equivalente a porcentagem de massa remanescente (%R). Os invertebrados foram identificados até o menor nível taxonômico possível e depositados na coleção de Invertebrados Límnicos – ICB - FURG. Para cada amostra foram calculadas a riqueza e a densidade de táxons, os índices de diversidade de Shannon - Wiener (H’), homogeneidade de Pielou (J). Para determinar qual grupo de invertebrados foi mais importante para a estruturação da comunidade em cada lago, foi realizada a análise de espécies indicadoras (indicator especies analysis). Um total de 32.399 organismos distribuídos em 38 táxons foram registrados para os lagos estudados. Dezoito táxons foram comuns entre os lagos em cada experimento. Um total de 1.449.612 ind. 100g PS no ambiente eutrófico e 372.380 ind. 100g PS para o ambiente oligotrófico foi registrado (p=0,4771). O táxon mais abundante encontrado para o lago eutrófico foi Goeldichironomus (Chironomidae; 81% de todos os organismos coletados), enquanto queno lago oligotrófico, o táxon mais abundante foi Caenis (Caenidae; 29,1% de todos os organismos coletados). A colonização do detrito foi rápida, nas primeiras 24 horas foram registrados 10 táxons nos lagos eutrófico e oligotrófico, sendo os predadores o grupo dominante (52 e 70%, respectivamente) neste período. Durante o período do experimento,no lago eutrófico, os coletores-catadores foram os mais abundantes (91,2 % do número total de organismos), seguido de coletores-filtradores (4,7 %) e predadores (3,5 %). No lago oligotrófico, os coletores-catadores foram os mais abundantes (34,1 % do número total de organismos), seguido de predadores (26,8 %), raspadores (24,9 %) e fragmentadores (10,5 %). O Índice de diversidade acompanhou os aumentos de densidade durante os experimentos, sendo que o valor máximo observado foi no lago oligotrófico(H’=2,31) no 60º dia de incubação, enquanto que o menor valor foi registrado para o lago eutrófico (H’=0,19) no 110º dia de incubação. A taxa de decomposição de S. herzogii foi diferente no lago eutrófico (k = 0,019; R2 = 0,88) e oligotrófico (k = 0,021; R2 = 0,81),porém essa diferença não foi significativa (ANCOVA; F = 6,38 e p = 0,6755).

Efeitos do cobre na macrófita potamogeton pectinatus L. e sua possível utilização o monitoramento ou remediação de ambientes aquáticos contaminados por este metal

O cobre é um metal essencial para as plantas, porém considerado tóxico quando em elevadas concentrações na água. No caso de macrófitas aquáticas já foi demonstrado que este metal inibe o processo fotossintético e provoca alterações pigmentares. Neste contexto, expusemos (96h) a macrófita aquática Potamogeton pectinatus (L.) à diferentes concentrações de cobre 1, 10, 100 e 1000 µM para avaliar o potencial bioacumulador da planta, e às concentrações de 1, 10 e 100 µM de Cu para verificar os possíveis efeitos do metal na taxa fotossintética (24 e 96h) em diferentes intensidades luminosas (17, 100, 300 e 500 µmol/m2 /s), no teor pigmentar (96h) e no crescimento das macrófitas (30 dias). Para os experimentos de bioacumulação mantivemos um grupo de plantas controle (sem adição de cobre no meio), enquanto que para os outros testes mantivemos um grupo controle e um grupo em solução nutritiva de Hoagland 100%, que contem cobre e outros micronutrientes em concentrações ideais para sobrevivência e crescimento de P. pectinatus. Nossos resultados mostram que a macrófita P. pectinatus é capaz de acumular altas concentrações de cobre, sendo que este acúmulo aumenta com a elevação dos níveis do metal na água. Apesar de basicamente não haver diferença estatística entre a concentração do metal nos diferentes órgãos da planta, as raízes mostraram-se capazes de acumular mais cobre que as folhas e caule com base no fator de bioconcentração. Com relação aos teores de clorofila “a”, “b” e carotenoides, estes foram menores nas folhas das plantas controle em comparação com as plantas em solução de Hogland, mas esta diferença só foi significativa nas plantas expostas ao cobre, que apresentaram menor concentração dos teores pigmentares já à 1 µM de Cu. Quanto à fotossíntese, em 24h de exposição, novamente observamos um efeito negativo da ausência e presença de cobre nas concentrações de 1, 10 e 100 µM, bem como, um efeito da luminosidade, de forma que as plantas em solução de Hoagland apresentaram maior taxa fotossintética quando em 100 µmol/m2 /s. Em virtude de um aumento na respiração em 96h, a fotossíntese, quando ocorreu, foi menor que em 24h e não diferiu entre os grupos e luminosidade. Em relação ao crescimento, as plantas perderam biomassa, mas mantiveram seus comprimentos e apenas aquelas em solução de Hoagland aumentaram seu número de folhas. Ainda, verificou-se clorose e necrose nas plantas controle e expostas ao cobre. Diante do exposto, concluímos que a macrófita P. pectinatus acumula altas concentrações de cobre, principalmente na raiz, sendo capaz e refletir as concentrações do metal no meio. Esta condição, sugere seu uso no biomonitoramento e fitorremediação de locais contaminados por cobre. Por outro lado, elas mostram-se sensíveis ao metal pela redução no teor pigmentar e fotossíntese, sugerindo estes como mecanismos toxicidade do cobre.

Wpływ czynników środowiskowych na układ odpornościowy i wczesno-sezonową aktywność chrząszczy z rodzaju Nicrophorus (Coleoptera: Silphidae)

Wydział Biologii: Instytut Biologii Środowiska

Influence of phosphine resistance genes on flight propensity and resource location in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae): the landscape for selection

Phosphine resistance in Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) has evolved through changes to enzymes involved in basic metabolic pathways. These changes impose metabolic stress and could affect energy-demanding behaviours. We therefore tested whether phosphine resistance alleles impact the movement of these insects in their quest for new resources. We measured walking and flight parameters of four T. castaneum genotypes: (1) a field-derived population, (2) a laboratory cultured, phosphine-susceptible reference strain, (3) a laboratory cultured, phosphine-resistant reference strain, and (4) a resistant introgressed strain that is almost identical genetically to the susceptible population. The temporal pattern of flight was identical across all populations, but resistant beetles took flight significantly less, walked more slowly, and located resources less successfully than did susceptible beetles. Also, the field-derived beetles (proved not to be carrying resistance genes) walked significantly faster and more directly towards food resources, and had a higher propensity for flight when compared to the susceptible laboratory beetles. These negative effects suggest survival of beetles with the resistance alleles will be compromised should they leave phosphine application sites. The field for selection therefore extends beyond the site at which phosphine fumigant imposed its effect, and other mutations are also likely to be affected in this way.