Forest culicinae mosquitoes in the environs of samuel hydroeletric plant, state of Rondônia, Brazil

Data on frequency and seasonal distribution of culicinae were recorded in the forest near a recently constructed hydroelectric plant - Samuel, in the State of Rondônia, Brazilian Amazon. Collections were performed almost daily from August 1990 to July 1991, between 6 and 9 p.m., using human bait. A total of 3,769 mosquitoes was collected, representing 21 species, including seven new records for the State of Rondônia. The most frequently collected species were Aedes fulvus (25%) and Ae. pennai (12.3%). The highest density for the majority of mosquito species coincided with the rainy season.

The parasitism of Ixodes luciae (Acari: Ixodidae) on marsupials and rodents in Peruvian Amazon

In this work the infestation with I. luciae on Didelphimorphia and Rodentia in different environments of Peruvian Amazon was studied. Didelphimorphia was represented by the family Didelphidae. Specimens belonging to Caluromys lanatus, Didelphis marsupialis, Marmosops sp.2, Metachirus nudicaudatus, Philander andersoni and Philander opossum were infested with adults I. luciae and one Micoureus sp. was infested with larvae. In Rodentia, the infestation with I. luciae nymphs was restricted to Hylaeamys perenensis, Hylaeamys yunganus and Oligoryzomys microtis, while one Oecomys bicolor (all Cricetidae) was infested with larvae of this species. The few larvae were found on rodents captured in primary forest. The only significant difference (P < 0.05) in prevalence of adult ticks on Didelphimorphia was between P. andersoni and M. nudicaudatus (chi-square distribution). Adult tick distribution was significant different in P. andersoni in comparison with M. nudicaudatus, P. opossum and D. marsupialis (Kruskal-Wallis test). No significant effect of month or environment was detected in relation to adult tick infestation on Didelphimorphia. The prevalence of nymphal infestation as well as tick distribution showed that H. perenensis and H. yunganus were significantly more prone to be infested with nymphs of I. luciae than O. microtis. Prevalence of nymph infestation was higher in primary and secondary forest than rural areas while abundance was higher in secondary forest when compared with rural areas (P < 0.05). Kruskal-Wallis test showed differences (P < 0.05) for nymphal infestation during December in relation to January, March, April and June. The natural cycle of I. luciae appeared to be continuous, bound to adult tick infestation on Philander and nymphal infestation on Hylaeamys in forested environs.

Effect of bird density on the decision to join a group in the Sicalis flaveola pelzeni (Passeriformes, Emberizidae)

A change in bird density within a captive flock of Sicalis flaveola pelzeni (Sclater, 1872) affected the decision to join a group. Ruling out inter-individual differences and maintaining constant the size of a food patch, birds were found to fly more often to the food source and spend a longer time in its environs when kept in greater groups.

Biologia do saguirú (Characidae, Curimatinae)

In Brazil all the fishes belonging to the sub-family Curimatinae are called « saguirú ». The present work gives a biological study of the Curimatus elegans Steind., a small fish without any economical importance, which is to be found along the whole brazilian coast, down till Paraguay. The specimens utilized for the present study come from Fortaleza (Ceará, north-eastern Brazil). The C. elegans is « ilyophagus », that means, it feeds itself exclusively with those organic materials to be found in mud, specially with microscopical algae. The intestines are very extent, some of them measuring about 9 to 11 times body's length. Studies have been made about growth and age of the C. elegans; the biggest sizes found were of 153 mm. for females and 88 mm. for males. The C. elegans shows developed sexual glands during a long period (April to September). The movements of the spermatozoa, in contact with water is of 40 to 50 seconds of intense movements, ceasing after 70 to 100 seconds. In contact with 0.5% NaCl-solution spermatozoa show a big increase in movements-time, that can last till about 25 minutes. The eggs' diameter measures 0.70 to 0.73 mm., mature and hydrated it attains 0.93 to 1,00 mm. There is a certain correlation between the size of the body and the quantity of eggs. Big specimens can produce a total of 200.000 eggs. The average quantity contained in 1 gr. and 1 cc. is 6018 and 6229 eggs, respectively. Maturity and spawning in laboratory has been obtained due to injections of suspension of fish-hypophysis. Three or four hours after the injection, fishes show more movement and evident signs of excitation, proceeding spawning after 5 to 6 hours. Males, persecuting females, describe successive circles (merry-go-round) - carroussel), swimming side by side with females up to water's surface, where sexual products are start beating dry, for there is no blood yet. Circulation-scheme is to be found on fig. 4 and 5. The swim-bladder and the stomach are but delineated; the intestine is formed by a cylindric tube, all closed. At the place, where later on there will open the mouth, we find a group of ciliary hairs that produce a liquid current, very evident by the semi-circle formed by attached solid particles. After 36 hours, opening of the mouth and formation of the gill slits begin. At the age of 90 hours (4 mm.) the larvas swim well and start to feed themselves; the digestive tube is now all open and the swimbladder works already. During the first days of life, larvas have an adhesive organ situated at their frontal region (fig. 7) in form of a crescent, by means of which they hang to surrounding vegetation (fig. 6). When the larva begins to swim and to feed itself and its yolk are having been absorbed. the adhesive organ retracts and disappears. While larvas and alevins feed themselves with plancton, they have small eye-teeth, which disappear,. when fishes become « ilyophagus ». There exist too, during their life as larvas, pharyngeal-teeth. The lateral line appears in the larva after 16 to 18 days; more or less at the same time all fins are completely developed. Shortly after, first scales appear (20 to 23 days). Evolution of intestines twisting followed (fig. 9). Larvas show at different parts of their bodies small of organs excretory functions, that are constituted by bottons in serial disposition, every one with an excretory canal that opens towards the outside. These formations disappear suddenly when larvas attain their phase of alevin. The existence of a great number of said formations at the caudal fin (fig. 12) is of great interest. In our experiences of breeding we have employed several thousands of C. elegans larvas in different environs and we made conditions of surrounding change (illumination), depth of water, temperature, presence of sand at bottom of aquariums and without sand, food). In this way we could compare the results obtained, estimate the action of each factor for the realisation of a good bring-up of larvas.

Physa acuta Draparnaud, 1805 (Gastropoda: Physidae): a study of topotypic specimens

A description is given of Physa acuta Draparnaud, 1805, based on topotypic specimens from the Garonne river basin, and additional samples from the environs of the French cities of Montpellier and Perpignan. It proved indistinguishable, in shell and anatomy, from topotypic Physa cubensis Pfeiffer, 1839, thus leading the authors to admit the synonymy of the two nominal species under the older name, P. acuta.

Diversity of Pentatomoidea (Hemiptera) in riparian forests of southern Brazil: taller forests, more bugs

Riparian forests are important features of any ecosystem, especially on grassland and savannah vegetation types. However, riparian forests in southernmost Brazil have received much less attention than elsewhere. This is the first quantitative study of pentatomoid (Hemiptera) diversity in the Pampa biome, surveying riparian forests of brooks and rivers in the environs of the municipality of Bagé, Rio Grande do Sul state, southern Brazil. The aim was two-fold: taxonomic characterization of the fauna and a primary ecological study of bug diversity. Sweeping net and beating tray were used to sample trees and shrubs on the border of sampling sites; sampling was carried out during three consecutive days, from March 28th to 30th 2006. Overall 154 individuals of 32 species of Pentatomoidea were captured, almost all species are new records for the local fauna. Taller forest canopy sites had higher abundance overall and higher species richness than shorter forest canopy sites. Of the 32 species, 11 were singletons and four were doubletons. There were no differences for pentatomoid species composition between the two environments differing in vegetation structure. Association to the Pampa biome of the most abundant species found are discussed. Although based on a rapid assessment protocol of faunal inventories, our results add important bioecological information to the pentatomoid fauna of the Pampa biome, especially associated to riparian forests.