Sex ratio and dynamic behavior in populations of the exotic blowfly Chrysomya albiceps (Diptera, Calliphoridae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Larval density, temperature and biological aspects of Chrysomya megacephala (Diptera: Calliphoridae)

Analisou-se o efeito de duas densidades larvais e duas temperaturas sobre a sobrevivência, fecundidade e tamanho corpóreo de C. megacephala em condições experimentais. Nenhum efeito simultâneo da densidade e temperatura foi encontrado sobre as variáveis investigadas em C. megacephala. Entretanto, foram observados efeitos isolados significativos da densidade e da temperatura sobre a fecundidade e tamanho corpóreo. A importância desses resultados para a dinâmica populacional de C. megacephala foi discutida.

Larval dispersal and predation in experimental populations of Chrysomya albiceps and Cochliomyia macellaria (Diptera: Calliphoridae)

In this study we investigated the larval dispersal associated with larval predation in experimental populations of Chrysomya albiceps and Cochliomyia macellaria. Frequency distribution of sampling units (G test) in the substrate was used to evaluate variation in larval dispersal. An experimental acrylic channel (1 x 0.1 x 0.2 m) covered with wood shavings was used to observe larval dispersal prior to pupation. The acrylic channel was graduated at 0.05 m intervals, each representing a sampling unit; hence, 20 sampling units were set up. A Petri dish containing third instar larvae of single and double species was deposited at one edge of the acrylic channel allowing larvae to disperse. The number of buried pupae (0, 1, 2, n) present in each sampling unit was recorded. For double species, the number of recovered larvae of C. albiceps was similar to the number initially released on the dish Petri. on the other hand, the number of recovered larvae of C. macellaria was significantly smaller than the initially released number. The results show that C. albiceps attacks C. macellaria larvae during the larval dispersal process. The larval distribution of C. albiceps did not differ significantly from C. macellaria in double species, but it differed significantly in single species. The larval aggregation level of C. macellaria decreased when C. albiceps was present and the larval aggregation level of C. albiceps increased when C. macellaria was present. The implications of such findings for the population dynamics of these species are discussed.

Rotifer abundance, biomass, and secondary production after the recovery of hydrologic connectivity between a river and two marginal lakes (São Paulo, Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The fish zonation of the Itanha,m river basin in the Atlantic Forest of southeast Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Larval dispersal and predation in experimental populations of Chrysomya albicieps and Cochliomyia macellaria (Diptera : Calliphoridae)

In this study we investigated the larval dispersal associated with larval predation in experimental populations of Chrysomya albiceps and Cochliomyia macellaria. Frequency distribution of sampling units (G test) in the substrate was used to evaluate variation in larval dispersal. An experimental acrylic channel (1 x 0.1 x 0.2 m) covered with wood shavings was used to observe larval dispersal prior to pupation. The acrylic channel was graduated at 0.05 m intervals, each representing a sampling unit; hence, 20 sampling units were set up. A Petri dish containing third instar larvae of single and double species was deposited at one edge of the acrylic channel allowing larvae to disperse. The number of buried pupae (0, 1, 2,...n) present in each sampling unit was recorded. For double species, the number of recovered larvae of C. albiceps was similar to the number initially released on the dish Petri. on the other hand, the number of recovered larvae of C. macellaria was significantly smaller than the initially released number the results show that C. albiceps attacks C. macellaria larvae during the larval dispersal process. The larval distribution of C. albiceps did not differ significantly from C. macellaria in double species, but it differed significantly in single species. The larval aggregation level of C. macellaria decreased when C. albiceps was present and the larval aggregation level of C. albiceps increased when C. macellaria was present. The implications of such findings for the population dynamics of these species are discussed.

Ploidy, sex and crossing over in an evolutionary aging model

Nowadays, many forms of reproduction coexist in nature: Asexual, Sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give I possible scenario. By studying the performance of Populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find all evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms oil Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations. (c) 2005 Elsevier B.V. All rights reserved.

Patch-size and isolation effects in the Fisher-Kolmogorov equation

We examine the classical problem of the existence of a threshold size for a patch to allow for survival of a given population in the case where the patch is not completely isolated. The surrounding habitat matrix is characterized by a non-zero carrying capacity. We show that a critical patch size cannot be strictly defined in this case. We also obtain the saturation density in such a patch as a function of the size of the patch and the relative carrying capacity of the outer region. We argue that this relative carrying capacity is a measure of the isolation of the patch. Our results are then compared with conclusions drawn from observations of the population dynamics of understorey birds in fragments of the Amazonian forest and shown to qualitatively agree with them, offering an explanation for the importance of dispersal and isolation in these observations. Finally, we show that a generalized critical patch size can be introduced resorting to threshold densities for the observation of a given species.

Stochastic Skellam model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modelagem matemática aplicada ao controle biológico de Ceratitis capitata Wiedemann (Diptera: Tephritidae) por Diachasmimorpha longicaudata Ashmed (Hymenoptera: Braconidae) em Citrus

O modelo matemático apresentado tem como objetivos: (1) simular as dinâmicas populacionais de um sistema hospedeiro parasitóide de três níveis tróficos composto pelas populações de mosca-do-mediterrâneo Ceratitis capitata (Wiedemann), vespa braconídea parasitóide Diachasmimorpha longicaudata (Ashmed) e frutos cítricos; (2) auxiliar no melhor entendimento dos principais fatores biológicos e ecológicos que regem as interações populacionais e (3) colaborar com programas mais eficientes de controle biológico para o sistema em questão. A metodologia empregada baseou-se na formulação de sistemas de equações de diferenças que descrevessem os processos de interação do sistema trófico. Posteriormente, foram elaboradas resoluções numéricas desses sistemas de equações e sua representação gráfica, utilizando-se o programa computacional Matlab, versão 6.1. Os dados biológicos e ecológicos necessários para a formulação das equações matemáticas foram fornecidos por especialistas em controle de C. capitata e retirados da literatura referente ao controle biológico das moscas-das-frutas em plantações de citros no Brasil, principalmente através da utilização de vespas parasitóides, como D. longicaudata. Os resultados obtidos nas simulações sugerem que o modelo proposto descreve adequadamente o sistema ecológico em questão e permite entender melhor suas principais características biológicas e ecológicas. em conseqüência pode auxiliar na escolha do modo e momento para liberação da vespa parasitóide para o controle mais efetivo de C. capitata.

Dinâmica populacional de ácaros fitófagos (Acari, Eriophyidae, Tenuipalpidae) em seis clones de seringueira no sul do Estado de Mato Grosso

Foi estudada a dinâmica populacional de Calacarus heveae Feres, 1992, Phyllocoptruta seringueirae Feres, 1998 (Eriophyidae) e Tenuipalpus heveae Baker, 1945 (Tenuipalpidae) em seis clones de seringueira (Hevea brasiliensis Muell. Arg.), com o intuito de conhecer a sazonalidade e as possíveis diferenças nos níveis de infestação dessas espécies sobre os diferentes clones, em seringal localizado no sul do Estado de Mato Grosso. Para isso, no período de março de 2004 a março de 2005, foram realizadas coletas num intervalo médio de catorze dias em seis parcelas clonais. em cada amostragem, foram analisados 100 folíolos de cada parcela, registrando-se o número total de ácaros encontrados em ambas as faces. Os níveis de infestação das espécies variaram entre os diferentes clones. O clone RRIM 600 apresentou maior abundância de T. heveae, enquanto que PB 235 e PB 260 de P. seringueira e C. heveae, respectivamente. Por outro lado, esse último clone apresentou menor número de indivíduos de T. heveae e P. seringueirae, e PB 235 de C. heveae. O primeiro semestre foi o período crítico de infestação, porém a duração da ocorrência e o pico de abundância dos fitófagos variaram nos diferentes clones.

Predicting the occurrence of alate aphids in Brassicaceae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Pragas e inimigos naturais na soja e no milho cultivados em sistemas diversificados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ácaros da família Phytoseiidae associados aos citros no município de Lavras, Sul de Minas Gerais

A ocorrência das espécies de ácaros predadores pertencentes à família Phytoseiidae, em folhas de laranjeira `Valência' (Citrus sinensis Osbeck), foi avaliada durante três anos em Lavras (MG), através de levantamentos quinzenais. Iphiseiodes zuluagai Denmark & Muma e Euseius alatus DeLeon foram as espécies mais freqüentes, a primeira representando 66,2% dos ácaros coletados e a segunda 29,8%. Ambos os ácaros foram encontrados ao longo de todos os anos, sendo que I. zuluagai apresentou maior ocorrência entre abril e setembro (outono e inverno), período de temperaturas amenas e baixa precipitação pluvial. A espécie E. alatus, ao contrário, apresentou maior ocorrência entre outubro e fevereiro, que correspondeu a um período de temperaturas elevadas e alta precipitação pluvial. Outras espécies levantadas e respectivas porcentagens de ocorrência foram: Amblyseius compositus Denmark & Muma (2,6 %), Amblyseius herbicolus (Chant) (1,1 %) e Phytoseiulus macropilis (Banks) (0,3 %), sendo A. compositus a mais freqüente e as demais ocasionais.

Dog culling and replacement in an area endemic for visceral leishmaniasis in Brazil

Measures employed to control visceral leishmaniasis in Brazil have focused on vector control by residual insecticide spraying and diagnosis of infection with elimination of positive dogs. We describe dog culling and replacement in a Brazilian endemic area (the Alvorada District, Aracatuba, SP) in order to better understand dog population dynamics when elimination of the dog reservoir is adopted as the main control measure. From August 2002 to July 2004, 60.9% of the estimated dog population for the area was culled with a mean age of 34 months old. The presence of anti-Leishmania sp. antibodies was recorded for only 26.7% of the euthanized canines. Replacement was observed in 38.8% of the cases, some of them by 2 or more dogs and in a mean time of 4 months. Dogs were replaced mostly by puppies of both sexes with a mean age of 6.8 months. From August 2002 to April 2005 we were able to follow-up 116 of these dogs, during a mean time of 8.7 months. Canine visceral leishmaniasis seropositivity by ELISA was observed in 42.2% of the followed dogs, 30.6% of which were already positive at the first evaluation. By the end of the follow-up period 37% of the dogs were submitted to euthanasia, with a mean age of 18.3 months. In the studied CVL endemic area of Brazil, euthanasia and the subsequent replacement ratio were high, increasing the dog population turnover and leading to a younger population that might be more susceptible to a variety of other infectious diseases in addition to CVL. Dog culling as a control strategy for VL should be reassessed. (C) 2008 Elsevier B.V. All rights reserved.