A new phytophagous Bracon Fabricius (Hymenoptera, Braconidae) associated with Protium ovatum Engl. (Burseraceae) fruits from Brazilian savannah

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

Direct and indirect top-down effects of previous contact with an enemy on the feeding behavior of blowfly larvae

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

The ecological causes of individual specialisation

University of Tennessee, KnoxvilleNational Science Foundation (NSF)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Horizontal distribution of megalopae of Brachyura (Crustacea, Decapoda) in a South American tropical estuary

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Big fish are the best: Seed dispersal of Bactris glaucescens by the pacu fish (Piaractus mesopotamicus) in the Pantanal, Brazil

We studied the potential role as seed disperser of the pacu fish (Piaracrus mesopotamicus, Characidae) in the Pantanal of Brazil. The most important food item in the diet of the pacu in the wet season was fruits of the palm Bactris glaucescens found in the guts of 73 percent of all fishes collected (N = 70). We found a positive relationship between fish length, weight, and gape size and the number of intact seeds in their gut. Therefore, large pacus are especially important in dispersing B. glaucescens seeds within the studied system. Since the best seed dispersers are the largest fishes, which are preferred by commercial fisheries, we predict that the ongoing over fishing in freshwater ecosystems will have major impacts on the dispersal system of fish-dependent plants. We suggest that it is paramount to change the attitudes in fisheries management of fruit-eating fishes and urgent to evaluate the impact of fishing on forest regeneration.

Chromosome analysis in Pseudopaludicola (Anura, Leiuperidae), with description of sex chromosomes XX/XY in P-saltica

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

Duration of Protopolybia exigua exigua (de Saussure) nests and related aspects as influenced by phorid fly infestation (vespidae, polistinae, epiponini)

The main characteristics of 55 nests of Protopolybia exigua exigua were periodically evaluated in Ribeirão Preto, southeastern Brazil. Although the queens' life-span can eventually reach one year, nests barely thrive for six months because most of them are periodically invaded by the scavenger phorid fly, Megaselia aff. picta. Under heavy infestation the adult wasp population partially closes the nest entrance, migrates and constructs a new nest in the neighborhood. Afterwards the old-nest's entrance can be completely closed by the wasps which results in blocking the parasitoid flies inside. In the tropics, predation by ants is considered the main selective pressure which shaped most of the bionomic characteristics of Polistinae wasps. It is suggested that Megaselia can easily overcome the usual wasps defensive tactics just because they are so specialized against ants. Aerial raids, fast erratic-jerking movements, rapid and efficient oviposition behavior, etc. can eventually turn Megaselia into a very important enemy of some social wasps.

Attack on Chestnut-bellied Euphonia nestlings by army ants

I report some observations of a Chestnut-bellied Euphonia (Euphonia pectoralis) nest in a lowland Atlantic Forest of southeastern Brazil during the early nestling period. During 7.5 hours of observations, the nest was attended 46.3% of the time, 45.6% by the female and 0.7% by the male. Unattended periods lasted 16-38 min. Parents visited the nest most of the time together at 36-59 min intervals. There were 1.06 feeding visits per nestling per hour. The two nestlings in the nest ended up preyed upon by army ants (Labidus praedator, Ecitoninae). The low height of the nest (0.8 m) may have facilitated its detection by the ants.

Feeding ecology, density and biomass of the freshwater turtle, Phrynops geoffroanus, inhabiting a polluted urban river in south-eastern Brazil

This study examines the ecology of a population of Geoffroy's side-necked turtle Phrynops geoffroanus inhabiting a polluted urban river in Ribeirão Preto city, São Paulo state, south-eastern Brazil. Adult turtles fed mainly on Chironomidae larvae and pupae (Chironomus cf. plumosus, 100% of occurrence frequency) and domestic waste, but they also consumed terrestrial items (cockroach, snails) and carrion. Juvenile turtles showed more feeding diversity than the adults and exhibited a trend for predation on Chironomidae pupae, but this is not reflected in resource partitioning. The elevated number of turtles (170-230 turtles/ha of river) and biomass (255-345 kg/ha of river) inhabiting this urban river is probably the result of the abundance of sewage and organic waste produced by humans, the absence of predators, and increased availability of nesting areas. Such factors convert this area into an environment highly advantageous for the survival of Geoffroy's side-necked turtle.

Sloths in the diet of a Harpy Eagle nestling in eastern Amazon

-Prey remains of a nestling Harpy Eagle (Harpia harpyja) over 15 months in eastern Amazon, Brazil included 11 two-toed sloths (Choloepus didactylus), 9 three-toed sloths (Bradypus variegatus), and 1 gray four-eyed opossum (Philander opossum). We found no evidence of predation on primates despite their abundance in the area and their importance to Harpy Eagles studied elsewhere. We observed no sloths in 605 km of line transects, a finding that suggests the inadequacy of transect data to estimate prey density for Harpy Eagles.

Ant exclusion and reproduction of Croton sarcopetalus (Euphorbiaceae)

A total of 20 insect species were observed on the extrafloral nectaries (EFNs) of Croton sarcopetalus. The most frequent ant species were Zacryptocerus sp., Crematogaster brevispinosa, C. scelerata, and Linepithema humile. Ants continuously patrolled the plants taking extrafloral nectar. Experimental data showed that there were no significant differences in either the degree of herbivory or in the reproductive output between control stems (with ants) and treated ones (without ants). We found no significant evidence of protection by ants mediated by EFNs in C. sarcopetalus. It is possible that the plant has other mechanisms than ant protection to prevent herbivore damage (e.g., hairs, latex, chemical defense). As this species occupies the southernmost distribution for the genus, the presence of EFNs in this species may be the remnant of a mutualistic interaction with the ants in tropical regions, where the abundance and diversity of ants and herbivores are comparatively higher. To draw accurate patterns in the genus Croton, further investigations in other species from tropical regions of South America are needed.

Energetic and physiological correlates of prey handling and ingestion in lizards and snakes

In this review, we summarize the energetic and physiological correlates of prey handling and ingestion in lizards and snakes. There were marked differences in the magnitude of aerobic metabolism during prey handling and ingestion between these two groups, although they show a similar pattern of variation as a function of relative prey mass. For lizards, the magnitude of aerobic metabolism during prey handling and ingestion also varied as a function of morphological specializations for a particular habitat, prey type, and behavior. For snakes, interspecific differences in aerobic metabolism during prey handling seem to be correlated with adaptations for prey capture (venom injection vs. constriction). During ingestion by snakes, differences in aerobic metabolism might be due to differences in cranial morphology, although allometric effects might be a potentially confounded effect. Anaerobic metabolism is used for prey handling and ingestion, but its relative contribution to total ATP production seems to be more pronounced in snakes than in lizards. The energetic costs of prey handling and ingestion are trivial for both groups and cannot be used to predict patterns of prey-size selection. For lizards, it seems that morphological and ecological factors set the constraints on prey handling and ingestion. For snakes, besides these two factors, the capacity of the cardio-respiratory system may also be an important factor constraining the capacity for prey handling and ingestion. © 2001 Elsevier B.V.

Breeding biology and nest site characteristics of the scarlet ibis in southeastern Brazil

The breeding biology of the only Scarlet Ibis Eudocimus ruber colony in southeastern Brazil was studied during the 1996-97 breeding season. The ibises began to visit their colony site by mid-September. Nest building and egg laying took place in early November and was synchronous, making the first nesting pulse. Mean clutch size in this pulse was 2.45 eggs/nest, and 0.67 young/nest reached age three weeks, when they were able to walk about the nest tree and environs. Predation was the main cause of nest failures (74% of all losses), followed by nest collapses (19%). A second nesting pulse, also synchronous, started in late December, when the young from the first nests were already able to wander about the colony and make short flights. Mean clutch size of this pulse was 2.05 eggs/nest and productivity was 0.34 young/nest. Nest collapses during storms accounted for 58% of the losses, and predation for a further 27%. A third pulse, with only a few nests, started when the second pulse young were in their third week, but no nest was successful. The incubation time was 21-24 days, and the young were able to fly well when 40 days old, deserting the colony by age 75 days. Nesting early in the breeding season yielded greater success. Nests were built close to each other (a sphere with a 1.8 m radius and centered on an average nest would include the four nearest neighbors) and there was always more than one nest per tree. Most nests were built on the upper third of the nest-tree and had some cover from overhanging branches. There was a trend for the ibises building their nests in even closer proximity during the second pulse, perhaps as a strategy to lessen individual predation risks. Received 30 August 2000, accepted 4 October 2000.

Structural characterization of nuclear phenotypes during Scinax fuscovarius spermatogenesis (Anura, Hylidae)

In anuran amphibian Scinax fuscovarius, the spermatogenesis occurs in structures called seminiferous loculi, in which germ epithelium is organized in spermatocysts. Each cyst contains cells in the same stage of cytodifferentiation. Characteristics of each cellular type and their groups made the identification and differentiation of the germ lineage cells possible. In the basis of the epithelium there are the spermatogonia I, the biggest cells and always associated with the Sertoli cell. After the phase of mitotic proliferation, the cysts containing variable number of spermatogonia II are originated, quite smaller and with cellular boundaries a little distinct. After differentiation and growth in volume, the spermatocytes I appear, the nuclei of which are spherical and with different degrees of compaction of the nuclear material. Starting the meiotic process, the spermatocytes II are originated, which by means of the second meiotic division become haploid cells, the spermatids I. These two last spermatocysts are very similar. In this phase, the cells will go through a prominent process of differentiation until they form the spermatids II, which are elongated and begin to be organized in bundles supported by prominent Sertoli cells. With the process of spermiogenesis, spermatozoa appear, usually observed in compact bundles with tails turned to the lumen and their heads fitted in their support cells. In more advanced stages, the spermatozoa can be observed free in the locular lumen, ready to follow the spermatic path.