248 resultados para FEMALE-BIASED SEX RATIO


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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Aiming qualitative improvements in the mass rearing of Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) in laboratory, tests were conducted with adults feed before parasitism on Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) larvae, using 14 artificial diets based on sucrose, brewer yeast and honey. The design was completely randomized with 15 treatments and five replications. The biological parameters evaluated in F1 and F2 generations were: number of adults emerged; sex ratio; adult emergence percentage; weight of pupae mass; and male and female longevity. The highest average of emerged adults were 85 in diet with sucrose 5% for F1 generation, and 91 in diet with sucrose 5% + yeast brewer 2,5% for F2; the smaller average of adult emergency were 63.60 in diet with honey 5% + yeast brewer 2.5 % for F1 generation and 66.80 in diet with honey 5% for F2. Diets that produced more females were honey 5% + yeast brewer 2.5%, showing the sex ratio of 0.82 for F1 generation, and sucrose 10% + 2.5% yeast brewer 2.5% (0.75) for F2, while sucrose 10% + yeast brewer 2.5% (0.60 for F1) and honey 2.5% (0.59) provided fewer females for F2 generation. The highest percentage of adult emergence were 93.90% with the diet containing sucrose 2.5% + yeast brewer 2.5%) and 93.89 % with honey 5% + yeast brewer 2.5%, and the lowest 81.71% (honey 5% + yeast brewer 2.5%) for F1 and 78.96 % (honey 5%) to F1 and F2, respectively. The diet with Mel 2.5% produced greater weight of pupae mass. The adult longevity did not differ significantly for all diets in F1 and F2 generations. Diets containing 5% or 10% of sucrose or honey provide, in general, improve the qualitative development of C. flavipes in mass rearing.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The aim of this study is to characterize some population biology parameters of P. squamosissimus, A. altiparanae and S. maculatus, the dominant fish species of the Santa Bárbara river, a tributary of the Nova Avanhandava reservoir, low Tietê river. Fish samplings were performed monthly between September/2002 and August/2003, using gill nets with different mesh sizes. Females of all species have larger standard lengths than males (Mann-Whitney, p < 0.0001), and are more frequent in superior size classes (Kolmogorov-Smirnov, p < 0.0001). All populations presented isometric growth, but differences between males and females were observed. Only P. squamosissimus presented a gender ratio different from 1:1, with a higher proportion of males (1:2, X2, p < 0.05). The onset of gonadal maturation occurs at 15 cm in P. squamosissimus, 9 cm in S. maculatus and at 8.9 cm in A. altiparanae. In all species populations, the adults predominate over juveniles. The allometric condition factor (K) of P. squamosissimus and S. maculatus presented higher values in the periods from March-May and June-August, and A. altiparanae in the period from March-May (Kruskal-Wallis, p < 0.05). These results indicate that the populations successfully exploit the lentic environment, and present life cycle tactics adapted to their particular means of environment occupation.

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Sexual development prior to gonadal sex differentiation is regulated by various molecular mechanisms. In fish, a molecular sex-differentiation period has been identified in species for which sex can be ascertained prior to gonadal sex differentiation. The present study was designed to identify such a period in a species for which no genetic sex markers or monosex populations are available. Siberian sturgeons undergo a slow sex-differentiation process over several months, so gonad morphology and gene expression was tracked in fish from ages 3-27 months to identify the sex-differentiation period. The genes amh, sox9, and dmrt1 were selected as male gonad markers; cyp19a1a and foxl2a as female gonad markers; and cyp17a1 and ar as markers of steroid synthesis and steroid receptivity. Sex differentiation occurred at 8 months, and was preceded by a molecular sex-differentiation period at 3-4 months, at which time all of the genes except ar showed clear expression peaks. amh and sox9 expression seemed to be involved in male sexual development whereas dmrt1, a gene involved in testis development in metazoans, unexpectedly showed a pattern similar to those of the genes known to be involved in female gonadal sex differentiation (cyp19a1 and foxl2a). In conclusion, the timing of and gene candidates involved with molecular sex differentiation in the Siberian sturgeon were identified. Mol. Reprod. Dev. 2015. © 2015 Wiley Periodicals, Inc.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The hermit crab Paguras brevidactylus (Crustacea: Anomura: Paguridea) from the infralittoral area of Anchieta Island, Ubatuba, was characterized by population Structure (size, sex ratio, reproduction and recruitment) and growth. Animals were collected monthly during 1999 by SCUBA diving. A total of 1525 individuals was collected (633 males and 892 females), 695 of them were ovigerous females. Overall sex ratio was 0.7:1 in favour of females. The crabs showed a unimodal distribution with males significantly larger than females. Ovigerous females were collected during all months and in high percentages from 1.0 mm of shield length, demonstrating intense and Continuous reproduction. The longevity was approximately 24 months for males and 18 for females, which showed larger growth rate and reached sexual maturity earlier (two months) than males. The low number of males in this Population may be due to the longer life span. Moreover, the sexual dimorphism favours males during the intra- and interspecific fights by shell, food, reproduction and territory. Females demonstrated a short life cycle and intense reproduction.

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

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Biological aspects of the blackmouth bass Synagrops bellus from the outer shelf and upper slope along the coast of São Paulo, southeastern Brazil, are presented. The species represented about 71.6% and 9.7% in number of the total catch performed by balloom trawl in the isobaths of 300m and 500m respectively. Body sizes of 266 individuals ranged between 130 and 265mm total length, with sex ratio of 55.9% males, and 44.1% females, where most individuals were in maturation stage. Twenty two food items were found, pointing out Myctophidae fishes, Penaeidea and Caridea shrimps, Brachyuran megalopae, Enoploteuthidae and Cranchiidae cephalopods, pteropods and tunicates. The intestinal coefficient increases as the body size increase, and the number of gill rakers ranged between 16 and 17. Length-weight relationship was WT = 6.0 x 10-6 x TL3.12, r2 = 0.9495. Synagrops bellus is an important link between zooplankton and micronekton, and demersal and pelagic predators in the outer shelf and upper slope in southwestern Brazilian coast.

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