Mesocosm experiment on the impact of invertebrate predation on zooplankton of a tropical lake

Invertebrate predation on zooplankton was investigated in mesocosms in the shallow tropical Lake Monte Alegre, Sauo Paulo State, Brazil, in the summer of 1999. Two treatments were applied: one with natural densities of prey and the predators Chaoborus brasiliensis and the water mite Krendowskia sp. (Pr+), and another without predators (Pr-). Three enclosures (volume: 6.6 m(3) of water per enclosure) per treatment were installed in the sediment of the deepest area of the lake (5.0 m). At the beginning, Chaoborus larvae were present in Pr- enclosures, because of technical difficulties in preventing their entrance, but they virtually disappeared in the course of the experiment. Water mites were almost absent in Pr- enclosures. Chaoborus predation negatively influenced the Daphnia gessneri population, but not the populations of the copepods Tropocyclops prasinus and Thermocyclops decipiens and the rotifers Keratella spp. Death rates of Daphnia were generally significantly higher in the Pr+ treatment; Daphnia densities increased after the disappearance of Chaoborus in Pr-. Copepod losses to predation in the experiment may be compensated by higher fecundity, shorter egg development time, and lower pressure on egg-bearing females, resulting in a lower susceptibility to Chaoborus predation. The predation impact of water mite on microcrustaceans and rotifers in the experiment was negligible.

Group size and composition of Guiana dolphins (Sotalia guianensis) (Van Bénèden, 1864) in the Paranaguá Estuarine Complex, Brazil

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

Resource use and coexistence of two syntopic hylid frogs (Anura, Hylidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nesting behavior of the swallow-tailed hummingbird, Eupetomena macroura (Trochilidae, aves)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Between-season attraction of cotton boll weevil, Anthonomus grandis Boh. (Coleoptera: Curculionidae) adults by its aggregation pheromone

O presente estudo teve como objetivo investigar a atratividade do bicudo do algodoeiro ao seu feromônio de agregação em período de inverno. Foram utilizados dois campos experimentais no município de Casa Branca, SP. em cada um destes, foram estabelecidas três áreas separadas de aproximadamente 500 metros, sempre próximas à vegetação de refúgio. Cada área foi dividida em três sub-áreas ou blocos de 100 m² para receber a aplicação do feromônio (2,5 g por bloco). Foi realizada uma contagem de bicudos adultos no solo antes, e mais cinco após a aplicação de feromônio. em cada bloco, foram observadas dez parcelas aleatórias, para a avaliação dos bicudos. Os adultos de A. grandis foram atraídos imediatamente após a aplicação do feromônio, sendo capturados por mais de 14 dias após. O índice mais elevado de atração foi observado 24 horas após a aplicação. A utilização do feromônio de agregação durante o inverno, pode aumentar a ação reguladora exercida pelos inimigos naturais, devido ao aumento de disponibilidade de presas. Controle químico pode ser recomendado 24 horas após a aplicação de feromônio em pequenas parcelas, como uma estratégia para a supressão de adultos de Anthonomus grandis em período de entressafra.

Carcass characteristics of broilers at 42 days receiving diets with phytase in different energy and crude protein levels

Objetivou-se, com este trabalho, estudar as características de carcaça e qualidade da carne do peito depois da inclusão de fitase em dietas para frangos de corte, com diferentes níveis de energia metabolizável aparente corrigida para nitrogênio (EMAn) e proteína bruta (PB) reduzida, suplementadas com aminoácidos essenciais seguindo o conceito de proteína ideal. Foram utilizados 1.500 frangos machos Cobb dos 22 aos 42 dias de idade com peso inicial de 833 ± 7 g e final de 2741 ± 48 g distribuídos em delineamento inteiramente casualizado em esquema fatorial 3x3+1 (três níveis de EMAn - 2950, 3100 e 3250 kcal/kg - e três de PB - 14, 16 e 18% - e um tratamento adicional - controle, sem fitase, com 3100 kcal/kg EMAn, 19,2% de PB e 0,4% de fósforo disponível) em seis repetições com 25 aves cada. Ao final do experimento, duas aves de cada parcela foram sacrificadas para a mensuração do rendimento de carcaça e de cortes e determinação da composição química da carne do peito. Os níveis de energia e proteína em rações com fitase influenciaram (P<0,05) os rendimentos de carcaça, peito e gordura abdominal a porcentagem de umidade, proteína e lipídios no músculo pectoralis major das aves, sendo os níveis de 3100 kcal EMAn/kg e 18% de PB os que proporcionaram maiores rendimentos de carcaça e de peito e menor deposição de gordura abdominal, mas em maior teor de lipídios na carne do peito. Conclui-se que a manipulação da energia em rações com reduzido teor de proteína e suplementadas com aminoácidos e fitase influencia o rendimento de cortes e a qualidade da carne do peito de frangos aos 42 dias.

Consequences of refuge for the functional response of Dermestes ater (Coleoptera : Dermestidae) to Musca domestica (Diptera : Muscidae)

It is well known that a predator has the potential to regulate a prey population only if the predator responds to increases in prey density and inflicts greater mortality rates. Predators may cause such density-dependent mortality depending on the nature of the functional and numerical responses. Yet, few studies have examined the relationship between the addition of refuges and the characteristic of functional response fits. We investigated whether addition of a refuge changed the type of functional response exhibited by Dermestes ater on Musca domestica, comparing the inherent ability of D. ater to kill houseflies in the absence and in the presence of refuge. An additional laboratory experiment was also carried out to assess handling and searching times exhibited by D. ater. Logistic regression analyses revealed a type III functional response for predator-prey interaction without refuge, and results were described by the random predator equation. The mean number of prey killed did not differ between experimental habitats, indicating that the addition of refuge did not inhibit predation. However, predators that interacted with prey without refuge spent less time searching for prey at higher densities, increasing predatory interaction. We concluded that this interaction may be weak, because data from experiments with refuge fitted poorly to models. However, the high variability and the nonsignificance of the data from the experiment with refuge show the importance of refuge for promoting spatial heterogeneity, which may prevent prey extinction.

Modeling the age-specific per capita growth and reproduction of Rhizobius lophanthae (Col: Coccinellidae)

A per capita model for the growth, development and reproduction of the coccinellid predator Rhizobius lophanthae (Blaisd) feeding on the oleander scale (Aspidiotus nerii Bouche (Homoptera: Diaspididae)) was developed. A thermal threshold for development of 9.4 degrees C was found. Under conditions of unlimited food, the relationship of mass at time t+1 to that at t (in days at 25 degrees C) suggests an 8.7 percent growth rate per mg larvae per day at 25 degrees C. An adult female beetle produces approximately 20 eggs per day while consuming an average of 8.5 scales/day. This is approximately 2.16 eggs per scale consumed above the maintenance level of 1.88 scales per day. More precisely, this compensation point is 0.12 mg of prey/mg of predator/day at 25 degrees C and the egestion rate is 1 - beta = 0.63.

A description of the growth of the major body components of 2 broiler chicken strains

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

The frog Dermatonotus muelleri (Boettger 1885) (Anura Microhylidae) shifts its search tactics in response to two different prey distributions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of Dietary Lysine Levels and Arginine:Lysine Ratios on Performance of Broilers Exposed to Heat or Cold Stress during the Period of Three to Six Weeks of Age

Four trials of identical experimental design were conducted to determine the effects of temperature, dietary Lys level, and dietary Arg:Lys ratios on performance and carcass yield of male broilers. Birds of a commercial strain were grown from 21 to 42 d of age in wire-floored finishing batteries placed in environmental chambers. The chambers were programmed to provide either a constant thermoneutral temperature (21.1 C), a constant cold temperature (15.5 C), or a cycling hot diurnal temperature (25.5 to 33.3 C). Within each environment there was a factorial arrangement of three Lys levels (1.0, 1.1, and 1.2%) with four Arg:Lys ratios (1.1:1, 1.2:1, 1.3:1, and 1.4:1). Environmental temperature significantly influenced virtually every characteristic examined. Hot cyclic temperatures reduced weight gain, feed intake, and breast meat yield, and increased feed conversion, dressing percentage, leg quarter yield, and abdominal fat content. The cold environment promoted increased feed intake and mortality. Ascites and cardiomyopathy were the leading causes of death under cold exposure and thermoneutral conditions, whereas complications arising from heat exposure were the main cause of death under hot cyclic conditions. Levels of Lys affected leg quarter yield and abdominal fat content over all environments but increased breast meat yield only under cold conditions. Increasing Arg: Lys ratios improved feed conversion and dressing percentage and reduced abdominal fat content; it could not be determined whether these responses were consistent with Arg per se or were due to a nonspecific N response. As increasing Lys levels or Arg:Lys ratios did not improve weight gain, increase breast meat yield, or attenuate adverse effects due to heat or cold exposure, it is concluded that the levels of Lys and Arg suggested for 21 to 42 d by the NRC are adequate for birds of this age under the environmental conditions encountered.

Expanded food choice as a possible factor in the evolution of sociality of Vespidae (Hymenoptera)

A recent theory suggests that economic considerations are more important than genetic ones in the emergence and maintenance of social behavior. Evolution of social behavior in wasps, thus, could be based on the development of worker castes, which increase the efficiency of brood care and energy use of the colony. If so, social wasps should collect a larger range of prey, favoring polyethism, as social behavior should increase the adaptive value of social species among wasps by increasing the range of prey accessible. We explored the literature and showed that the Eumeninae, which are mostly solitary, draw prey from significantly fewer orders of arthropods than wasps in the subfamily Vespinae and Polistinae, which are mainly social, supporting the hypothesis that social behavior may have emerged as a more efficient way to feed and care for the young by opening a wider range of food sources, increasing the amount of food and quality of care provided to the young. Two alternative explanations of this data are also discussed.

Cryptococcosis outbreak in psittacine birds in Brazil

An outbreak of cryptococcosis occurred in a breeding aviary in São Paulo, Brazil. Seven psittacine birds (of species Charmosyna papou, Lorius lory, Trichoglossus goldiei, Psittacula krameri and Psittacus erithacus) died of disseminated cryptococcosis. Incoordination, progressive paralysis and difficulty in flying were seen in five birds, whereas superficial lesions coincident with respiratory alterations were seen in two birds. Encapsulated yeasts suggestive of Cryptococcus sp. were seen in faecal smears stained with India ink in two cases. Histological examination of the birds showed cryptococcal cells in various tissues, including the beak, choana, sinus, lungs, air sacs, heart, liver, spleen, kidneys, intestines and central nervous system. High titres of cryptococcal antigen were observed in the serum of an affected bird. In this case, titres increased during treatment and the bird eventually died. Yeasts were isolated from the nasal mass, faeces and liver of one bird. Cryptococcus neoformans var. gattii serovar B was identified based on biochemical, physiological and serological tests. These strains were resistant (minimum inhibitory concentration 64 μ g/ml) to fluconazole. This is the first report of C. neoformans var. gattii occurring in psittacine birds in Brazil. © 2004 ISHAM.

Osteologia craniana de Nyctibiidae (Aves, Caprimulgiformes)

The Potoos form an exclusively neotropical family of nocturnal birds distributed throughout Central and South America, except Chile, and reaching their highest diversity in the Amazon region. The seven currently recognized species are certainly among the most poorly known birds of this region. They are characterized by a distinctive mimicry of vegetal trunks, where they remain almost motionless during daytime. For this reason, their nocturnal and cryptic habits make them exceedingly difficult to study. Published accounts on behavior and natural history of the family are scarce and contributions regarding its anatomy are rare. Here we sample six of the seven currently recognized species of Nyctibiidae, including Nyctibius grandis, N. aethereus, N. griseus, N. jamaicensis, N. leucopterus and N. bracteatus, in order to conduct a detailed and illustrated description of the skull and jaw osteology. High interspecific variation in skull osteology was observed in the family. Species of this family possess a highly modified skull, adapted to their life habits, which shelters their well developed eyes and permits a large mouth opening. The bones that form the palate structure exhibit a dorsoventral flattening, particularly in the pterigoid and parasphenoid bones, with the palatine bone being a broadly developed, wing-shaped structure. In the maxilar region, near the jugal arch, there is a tooth-like projection, unique among birds, which may assist in the retention of prey upon capture. The vomer bone is highly variable within the family, showing varying numbers of rostral projections amongst species. The broad occipital region exhibits large spacing between the quadrate bones, which are vertically disposed and possess a reduced processus orbitalis. The mandible, which is flexible and elastic, has an extremely short symphyseal region and sindesmotic joints in both mandibular rami. As a family, potoos possess a highly specialized skull which provides insight into the relationship between the form of the structures and the feeding habits of the species. Furthermore, the large interspecific variation in skull morphology emphasizes the needs for taxonomic revision within the family, which at present is lumped into a single genus.

Experimental infection of commercial layers with wild or attenuated Salmonella Gallinarum mutant strains: Anatomic pathology, total blood cell count and serum protein levels

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