Flight activity of Plebeia pugnax Moure (in litt.) was studied in six colonies coming from Cunha, SP, from July to October 1994. Twice a week, from 8:00 a.m. to 6:00 p.m., for 5 minutes every half-hour, all the bees entering and leaving the hives were counted. Six hundred counts were made and the materials that foragers carried were recorded. Data were analysed in relation to temperature, relative humidity, light intensity and day time. Foragers' flight activity was relatively constant in a wide range of temperature, from 22 degrees C to 34 degrees C. The minimum temperature for the beginning of flight activity was 14 degrees C. Effective flight activity (when foragers of all colonies were leaving the hives) occurred at 15 degrees C. These bees also flew within a wide range of relative humidity, from 30% to 100%, decreasing slowly after 50%. Flight activity increased as light intensity rose and it has also increased as the hours passed by, reaching a peak around midday and decreasing gradually afterwards. Pollen was collected all day long, while resin collection was relatively constant and debris transportation was slightly higher after 10:00 h. From all known Plebeia species, this one flew on the lowest temperature ever registered for this genus.
In this paper, the seasonal abundance of 25 sandfly species (1 of the Brumptomyia genus and 24 of the Lutzomyia genus) found at P1V5, municipal district of Buriticupu, Maranhão State, is discussed. The capture was carried out from 18:00 P.M. to 6:00 A.M., once a month, from January to December 1996. CDC light traps were set up in the forest, in the peri and intradomicile environments. Five species were only found in the rainy season (January to June), being represented by one or two individuals; eight species occurred only in the dry season (July to December) and eleven species appeared in both seasons. The most frequent species in the dry period were: L. whitmani (26.3%), L. serrana (23%), L. choti (22.8%), L. evandroi (7.5%), L. longipalpis (5.8%), L. termitophila (3.3%), L. shannoni (3%) and L. migonei (2.5%). In the rainy season, L. whitmani was the prevailing species (74%), followed by L. termitophila (4%), L. umbratilis (3.4%), L. serrana (2.8%), L. evandroi (2,8%) and L. claustrei (2.4%). L. whitmani was thought to be an annual species, occurring in the entire year of study. The others species, with exception to L. serrana and L. evandroi , showed a seasonal, punctual or peripheric pattern.
Four size fractions of the sediment of six environments of the upper Paraná River floodplain were analyzed for carbon, nitrogen, and phosphorus contents and microbial respiration (oxygen consumption). Particle size did not affect nitrogen and phosphorus content or microbial activity, but did affect carbon content (F = 4.274, df = 3; 20, p = 0.020). The carbon concentration of ultra-fine particles was significantly lower than that of other sizes of sediment particles. Microbial respiration values were well predicted by sediment chemical composition, as shown by multiple regression (microbial respiration = -0.39 - 0.210C + 0.108N + 0.796P; F = 7.0495, p = 0.0022). However, phosphorus was the element which best explained the microbial respiration (partial coefficient = 0.796, p = 0.0039, n = 23). Considering that i) phosphorus was the best predictor of microbial respiration; ii) phosphorus is trapped in the series of reservoirs located upstream from the section of the floodplain studied; and iii) microbial respiration is a measure of decomposition rates and nutrient cycling, we hypothesize that the long-term accumulation of litter detritus and reduction of nutrient cycling in environments of the upper Paraná River floodplain are probable impacts of this decrease in phosphorus caused by the upstream reservoirs.
Diet of 364 specimens of the dourado (Salminus maxillosus) was studied monthly at Cachoeira das Emas from November/1996 to May/1998, considered the breeding ground of this and other migrant fishes of Mogi-Guaçu River. Only adults were found at this site, and diet consisted exclusively of fish, with predominance of Leporinus sp. Seasonal variation in feeding activity was highest during some months of the rainy and hot season (September-December), when fish composition and number of prey species consumed also changed. These modifications were primarily attributed to an increase in food availability at the site of study during the rainy season, once most of the migrant species, including small Characidae concentrate there at this time of year. Apparently diet shifts, prey availability and rainfall are intimately related, representing a combination of factors that may account for the observed patterns of resource exploitation.
Three options of water temperatures in a thermal gradient that changed from 22 to 35 degrees C were offered to Pantanal caiman (Caiman croocodilus yacare) hatchlings. Animals from two nests were submitted to temperatures during 19 days (Nest 1 -- 20 caimans caught in the nature hours after hatching), corresponding to 1 to 7 observations periods, and 13 days (Nest 2 -- 20 animals obtained by artificial incubation) relative to observation period 8. Caimans remain fasting during experimental period. Hatchlings were allocated in a enclosure containing three styrofoam boxes (120 L) disposed side by side enclosed by wire netting and filled with water to the top. Thus, the animals were free to access the boxes, which temperatures were changed at the end of each observation period to avoid position effects. Air temperature was keep close to 22 degrees C by air conditioning and water temperature was controlled by thermostats. The trial was divided in three phases determined by elimination of the less frequented temperature and its substitution by another temperature. In a first phase of the experiment that contained 1, 2 and 3 observation periods, the thermostats were regulated to 22 degrees C (BoxD), 26 degrees C (BxC) and 32 degrees C (BxA). In phase 2 to 26 degrees C, 29.5 degrees C (BxB) and 32 degrees C, including 4, 5 and 6 periods. In the third phase that included 7 and 8 periods, the thermostats were adjusted to 29.5 degrees C, 32 degrees C and 35 degrees C (BxE). The number of caimans in each box was recorded two to three times a day (8:00, 14:00 and 17:00h) before pointed water temperature. Mean water temperatures (+ standard deviation) and respective caiman frequency means by box/temperature were: Phase 1 (BxD/22.3 +/- 1.2 degrees C - 10.3%; BxC/27.0 +/- 2.4 degrees C - 32.0% and BxA/31.2 +/- 1.1 degrees C - 57.6%); Phase 2 (BxC/26.6 +/- 2.8 degrees C - 13.3%; BxB/29.3 +/- 2.2 degrees C - 27.7% and BxA/31.3 +/- 1.2 degrees C - 59.0%) and Phase 3 (BxB/29.5 +/- 3.6 degrees C - 23.7%; BxA/31.0 +/- 2.2 degrees C - 31.9 and BxE/34.0 +/- 2.2 degrees C - 44.4%). Observing that in the phases 1 and 2 the box with hottest water (CxA) was more frequented. In the phase 3, the difference between higher and smaller frequency straiten to 20.7%, in relation to almost 46.5% in phases 1 and 2, indicating that water temperatures between 29.5 and 35 degrees C resulted in body temperatures more next to the comfort zone, in the experimental conditions.
Nectar of nocturnal flowers may be used by diurnal species that occasionally accomplish secondary pollination. Thirteen bird species visited Caryocar brasiliense flowers in central Brazil. There is a temporal separation between nectarivores and non-nectarivores species. Nectarivores birds visited flowers late in the morning, while other species appear earlier. C. brasiliense nectar may be an alternative resource to birds visitors during the dry season.
The diet of the arboreal lizard E. bilineatus was assessed based on analysis of gut contents of specimens collected in the remnants of the Atlantic rainforest in Espírito Santo State, south-eastern Brazil. Stomachs of the lizards examined (SVL = 57.0-85.0 mm) contained nine arthropod orders. E. bilineatus utilizes a broad range of arthopodan prey type and sizes, and can be considered an arthropod generalist, which uses a sit-and-wait foraging strategy. Orthoptera represented the most important food item, followed by Dictyoptera and Hymenoptera. Hemiptera, Homoptera, Lepidoptera (larvae), Coleoptera, Araneae, and Diplopoda constituted the remainder of food items. The presence of Diplopoda, which are not generally found on tree trunks, provides particularly strong evidence the E. bilineatus forages in leaf litter on the ground.
This study describes the morphology of the digestive apparatus and the size and organic content of the ingested food of five species of benthic-feeding fishes (Prochilodus lineatus, Steindachnerina insculpta, Loricariichthys platymetopon, Trachydoras paraguayensis e Iheringichthys labrosus). The samples were taken in the floodplain of the up Paraná River in February and August 1991. The results suggested that these species have different mouth, teeth, gill rakers, stomach and intestine length. These morphologic characteristics were related with the type, size and nutritional quality of the food ingested. Although these species feed on the bottom, the morphologic divergences probably explain the differences in diet.
The objective of the present study was to adapt techniques for the histological processing of Dugesiidae cocoons for the study of embryo development. The cocoons were fixed with formalin, SUSA, Bouin or paraformaldehyde/glutaraldehyde and subsequently embedded in Paraplast or glycol methacrylate (Historesin). Paraplast embedding yielded reasonable results only after the cocoon was perforated or fixed for a prolonged period of time using softening techniques with acid solutions. When the SUSA or Bouin fixative and Historesin embedding techniques were used the results were good for light microscopical analysis. Fixation with paraformaldehyde/glutaraldehyde and glycol methacrylate embedding resulted in better tissue preservation, and did not require prolonged fixation or softening techniques. Thus, we suggest this technique for light microscopical analysis of embryo development in Dugesiidae.
The reproductive and feeding biology of the lined seahorse, Hippocampus erectus, was studied in Chesapeake Bay. Seahorses are monogamous, and males incubate the eggs received from females in a closed brood pouch (= marsupium). Females do not play any parental care after mating. Total sex ratio and the operational sex ratio was strongly skewed toward females. Males and females had similar number of eggs/embryos and hydrated oocytes, respectively. The number of eggs/embryos found in the male brood pouch varied from 97 to 1,552 (fish from 80 to 126 mm TL), whereas the number of hydrated oocytes in female varied from 90 to 1,313 (fish from 60 to 123 mm TL). Both, the number of eggs/embryos and hydrated oocytes were better linearly correlated to total weight than to total length. The small snout and mouth size limits the feeding of the lined seahorse to small prey size. Amphypods were the predominant food items found in the guts, especially Ampithoe longimana, Gammarus mucronatus, and Caprella penantis. The lined seahorse is not abundant in Chesapeake Bay, but keeps a breeding population which is probably brought inside the bay by currents on drifting vegetation. Chances to find a partner may be difficult because of its low abundance, due to turbid waters, and its sedentary behavior.
The present paper reports the presence of great quantities of electrondense intercellular material in the follicular epithelium of P. microps. The material apparently is uptaken from circulation and enter the follicle through the intercellular spaces accumulating in the epithelial median-apical intercellular spaces and in perioocytic space. The accumulation starts in the early growth of the primary oocyte and proceed until vitellogenesis. The possible chemical nature and function of the deposits are discussed.
I studied the existence of sentinels in Saltator atricollis in a 'campo-cerrado' (Brazilian savanna) during the breeding seasons of 1994-95 and 1995-96. Groups of this species consisted of two to seven birds (N = 25). Sentinels were present (mean +/- sd) 62% +/- 9% of the time, and most sentinel bouts lasted from less than one to six minutes (although in some occasions for more than 30 min.). Overlap of two or more sentinels occurred on average only 3.2% of the time with birds on guard. Sentinels commonly gave contact calls in the beginning and/or at the end of a sentinel bout. The group size had no effect on time with sentinels. However the encounter rate between raptors and groups significantly influenced the time guarded. The results of this study suggests that the ability of sentinels to detect predators may play a central role as an anti-predator device.
A survey was conducted to determine the density and species composition of viable seeds buried in four stands of a tropical montane forest at Parque Estadual Intervales, Brazil. The objective was to understand: (1) how numbers and composition of the soil seed bank change as the forest regrows, and (2) how such changes affect the species available for regeneration if forests of different ages are cut down. In each forest stand (5, 18, 27-yr-old and a mature forest), 57 soil samples were collected (0-2.5 and 2.5-5 cm deep). Viable seed density of herbaceous species ranged between 11,003 seeds. m-2 (5-yr-old vegetation) and 482 (mature forest), and between 25 (5-yr-old vegetation) and 389 seeds. m-2 (mature forest) for woody plant species in the 0-5 cm soil layer, suggesting a decrease in seed stocks in the course of forest regeneration. Seeds buried in the 0-2.5 cm soil layer represented between 56.9% and 67.4% of all viable seeds. Most of the viable seeds belonged to weeds of Asteraceae, Poaceae, Malvaceae and Solanaceae. The results provide evidence that, in forests of different ages, the soil does not store seeds of the same key ecological groups involved in the regeneration of Atlantic forest. Allochthonous seeds from remaining patches of forest, as well as their vertebrate dispersers, are needed for forest regeneration since the soil seed bank does not store large seeds of shade-tolerant species.
Associated to the sting apparatus of the aculeate hymenopterans is found the poison gland, originated from the glands associated to the ovipositor of the non-aculeate hymenopterans and the less derived Dufour gland, homologue of the coletterial gland of other insects, and found in all hymenopteran females. The Dufour gland functions is mostly uncertain in hymenopterans but in ants it is involved with communication and defense and in non social bees with the nest building and protection. In wasps possibly with kin-recognition. Differences in morphology and chemical composition of the gland secretion were observed among species, in the same species, between the castes in the social species and among individual of the same caste playing different tasks or belonging to different nest. Its original function of egg-protective substance producing, or favoring the oviposition, appear to have been replaced or complemented in hymenopterans by the production of semiochemicals with function in communication.
The isothermal deterministic model adherence was studied to evaluate the population dynamic of Synthesiomyia nudiseta (Diptera, Muscidae). The linear form of equation obtained for the experiments in the several phases, were for Egg: 1/D = -0.18 + 0.02. T; Larva: 1/D = -0.028 + 0.01. T; Pupa: 1/D = -0.069 + 0.01. T; and Adult: 1/D = -0.4178 + 0.02. T. In function of temperature, S. nudiseta can present from 4.18 to 8.95 and from 4.91 to 8.99 generations per year, when calculated through the equations of development and through the simulations, respectively. And the higher the temperature the larger the generation number. Through variance analysis it was verified the significance for the regression equations in relation to the annual generation number (Ng/year) of S. nudiseta in function of the isothermals, for two studied situations. It was obtained a significance of 0,1%. The regression equations obtained for these situations were: Ng/year = 5.4 + 0.5. T and Ng/year = 5.1 + 0.52. T. The number of generations of S. nudiseta varies linearly with the isothermal. Besides that, the number of annual generations for each isothermal does not differ statistically when calculated through the development equations or through the simulations. Such conditions suggest the adaptation of the deterministic model adopted.
Species richness, abundance, distribution and similarity between cave invertebrate communities were compared among seven caves located in the Peruaçu River valley, north of Minas Gerais State, Brazil. Such comparisons aimed to determinate the degree of biological complexity in the sampled caves, calculated by the "Index of Biological Complexity in Caves", presented in this manuscript. The presence of potential or real impacts on the cave fauna was also investigated. A total of 1,468 individuals belonging to 57 families of: Acarina, Pseudoscorpionida, Araneida, Opilionida, Amblypygi, Isopoda, Geophilomorpha, Scutigeromorpha, Spirostreptida, Coleoptera, Collembola, Diptera, Dictyoptera, Ephemeroptera, Ensifera, Heteroptera, Hymenoptera, Lepidoptera, Plecoptera, Psocoptera, and Trichoptera was collected. Caves with higher resource availability (as those hidrologicaly actives) had a higher biological complexity than those with less resource. There are two types of impacts that occur in the area: the natural (geological) and the anthropic, as intense "stepping" and visitation or use of cave entrances as cattle shelters. There are caves with different preservation degrees in the area, with invertebrate communities in varied complexity states. The communities of these caves undoubtedly deserve care, since the area is extremely important in the Brazilian biospeleological context.
The Energetic Equivalence Rule (EER) is a controversial issue in ecology. This rule states that the amount of energy that each species uses per unit of area is independent of its body size. Here, we perform a meta-analytical procedure to combine and compare the slopes of population density and body size relationships across independent studies of mammals and birds. We then compared a distribution of 50,000 bootstrap combined slopes with the expected slope (b = -0.75) under the EER. The combined slopes obtained for mammals and birds separately were -0.755 and -0.321, respectively. The homogeneity hypothesis (i. e. within studies the slopes differ by no more than would be expected due sampling variation) was rejected in both cases. So, EER cannot be supported since the use of an exponent of -0.75 is, in fact, an oversimplification. Significant heterogeneity of slopes within each group (mammals and birds) is an indicator of inferential problems related with variation in body size, spatial scale, the regression model adopted and phylogenetic relationships among species. So, we consider that questions regarding the estimation and validity of slopes is the next challenge of density-body size relationship studies.
To investigate the influence of the pineal gland through melatonin secretion on the physiological and morphological parameters of pancreatic islets, we studied the plasma biochemistry and morphological and morphometric characteristics of the endocrine pancreas of male Wistar rats. The animals were distributed into five groups of ten rats each: NC - normal control group; NS -- sham-operated group; Px (25) -- pinealectomised group, studied 15--25 days after surgery; Px (70) -- pinealectomised group, studied 60-70 days after surgery; ALX - alloxan monohydrate-treated group. Data are analyzed statistically by ANOVA and by the Kruskal-Wallis test. Although there was no significant difference in plasma glucose or insulin levels between the Px (25), Px (70) and NC groups, Px (25) animals showed a tendency to increased glucose and reduced insulin levels. The ALX group showed a clear elevation of plasma glucose and a reduction of plasma insulin compared to the other groups. Morphometric analysis showed a larger pancreatic islet area and a lower pancreatic islet density in the pancreas of Px (70) animals and an increase in degenerative pathological processes in the pancreatic islets of the Px (25) and ALX groups. The present results suggest that melatonin, in addition to acting on tissue sensitivity to insulin (as reported in other studies), affects the secretory action of beta cells, as demonstrated by the morphological and morphometric changes observed in pinealectomised animals.
Three tinctures samples from extracts of the popular medicinal plant Thuya occidentalis were tested in vitro through two short term tests for measuring the activity of genotoxic chemicals. Using the Salmonella/mammalian-microsome (Mutatest) assay and the SOS-chromotest (induction of beta-galactosidase in Escherichia coli), none of the extract was effective in inducing mutagenesis or beta-galactosidase synthesis (as an indicator of general and early sign of DNA damage), even with metabolization.
Food habits and daily feeding activity of fish populations are important ecological variables for understanding their role in the ecosystem. Diel changes in feeding activity and dietary composition of juvenile whitemouth croaker Micropogonias furnieri, shortfin corvina Isopisthus parvipinnis, shorthead drum Larimus breviceps and of juvenile and adult banded croaker Paralonchurus brasiliensis were investigated from samples taken over a 24 hours period from 4 to 5 September 1987 on the continental shelf off South-eastern Brazil. Whitemouth croaker and banded croaker had a benthic diet based on polychaetes and some caridean shrimps and showed no diel feeding pattern. Shortfin corvina and shorthead drum fed on crustaceans and teleostean fish, the former species primarily on pelagic sergestid shrimps and benthic caridean shrimps, and the latter mainly on pelagic sergestid shrimps, mysidacean and benthic caridean shrimps. Shortfin corvina is primarily a diurnal feeder, but preyed on some items only at night. Shorthead drum is a night feeder, with minimum stomach fullness values between dawn and daytime, and maximum values between dusk and night time.
