Repositório RCAAP

This study was designed to characterize the interactions between Ludwigia elegans flowers and visiting bees during two years in two areas 200 km apart, at the same latitude (approximately 22º48'S) but at different altitudes (Alumínio, 600 m, and Campos do Jordão, 1500 m), in the State of São Paulo, Brazil. As these flowers open simultaneously in the morning and lose their petals by sunset, interaction with bees occurs only during the photophase. Flowers of L. elegans were mainly visited by bees, the most frequent species being: Tetraglossula anthracina (Michener, 1989) (Colletidae), Rhophitulus sp. (Andrenidae), and Pseudagapostemon spp. (Halictidae), all considered specialized bees for collecting pollen and nectar from these flowers, as well as the generalist bee Apis mellifera Linnaeus, 1758 (Apidae). The specialist bees were temporally adjusted to the opening schedule of the flower, which occurs primarily in the morning, but shows a circannual variation. T. anthracina appears in both study areas, but only between December and April. The annual activity patterns of these specialist bees are synchronized to the phenology of L. elegans. Photoperiod and temperature cycles are suggested as the main synchronizers of both bees and plants.

Spodoptera frugiperda, the fall armyworm, is a very significant polyphagous pest due to the damages it causes, and control difficulties. Lack of information about its impact on sweet corn motivated a comparison of its biology, with respect to the larval and pupal stages, among the genotypes ELISA, BR 400 (sweet corns), and BR PAMPA (field corn). In laboratory conditions (25 ± 1ºC; 70 ± 10% RH; photophase 12 hours), 35 caterpillars were individualized and fed daily with 3.14 cm² sections of corn leaves from the referred-to genotypes, cultivated in plots in the experimental area of the Departament of Fitossanidade, UFRGS, Porto Alegre, RS from October to November 2000. The caterpillars were weighed daily; after each molt, the cephalic capsules were collected and measured (in width), to establish growth rate; pupae were weighed and sexed when 24 hours old. The duration of the larval instars, the pupal sex ratio, and the mortality of larvae and pupae were evaluated. In the first three instars there were no differences registered in capsule width. In the fourth and fifth instars, capsules of caterpillars kept in BR 400 were smaller. The weight of caterpillars and pupae, instar duration and sex ratio did not differ among the genotypes. Pupal phase duration was less in females kept in BR 400. Mortality was greater in the larval phase in ELISA and in the pupal phase in BR PAMPA.

Twelve stream segments were sampled four times in 1998-1999 (one sampling per season) in the drainage basin of the upper São Francisco River (19º45'-21º25'S, 49º05'-51º30'W), situated in Serra da Canastra National Park, at altitudes ranging from 1,175 to 1,400 m. The macroalgae survey resulted in 30 species, with a predominance of Cyanophyta (12 species = 40%) and Chlorophyta (11 species = 36.5%) and a lower proportion of Rhodophyta (seven species = 23.5%). Two species, Klebsormidium rivulare (Chlorophyta) and Kyliniella latvica (Rhodophyta), were new records for Brazil. Capsosira sp. and Stigonema sp. (Cyanophyta) and the "Chantransia" stage of Batrachospermum (Rhodophyta) were the most widespread macroalgae, occurring in six sampling sites, whereas 11 species were found at only one site. The proportion of macroalgal morphological types were as follows: mats (33%), free filaments (27%), gelatinous filaments (27%), crusts (7%), tufts (3%), and gelatinous colonies (3%). The flora revealed few species in common (4%-8%) with stream macroalgae from other Brazilian regions. The macroalgal communities proved to have species richness values close to the highest values reported in previous studies. The patterns typical for stream macroalgal communities (patchy distribution and dominance of few species) were also found in this basin. However, the stream variables most influential in macroalgal distribution in this study (rocky substratum, low pH, high COD, water color, and current velocity) were essentially the same that best describe the limnological characteristics of this lotic ecosystem. In addition, this combination of variables differed sharply from results of previous studies in other Brazilian stream ecosystems.

Individuals of two populations of Trichogramma maxacalii (Hymenoptera: Trichogrammatidae) were collected from eggs of Euselasia apisaon (Lepidoptera: Riodinidae), a lepidopteran defoliator of Eucalyptus, in plantations in the states of São Paulo and Minas Gerais, Brazil. This study investigated the sex ratio, number of parasitoids per egg, and longevity of individuals of these two populations of T. maxacalii, when this parasitoid was reared receiving eggs of the factitious host Anagasta kuehniella (Lepidoptera: Pyralidae) in different periods after emergence, and with or without honey. Sex ratio of T. maxacalii varied from 0.44 to 0.60, and was affected by the interaction between populations, availability of food (honey), and length of time in which the parasitoid stayed without host eggs after their emergence. The population of T. maxacalii collected in São Paulo produced a larger number of individuals per egg of the host A. kuehniella and lived longer when fed.

The influence of the photoperiod on the biology and seasonal morphs of Dichelops melacanthus (Dallas, 1851) was studied in the laboratory. Four different photoperiods (11, 12, 13, and 14 hL = hours of light) were tested, keeping the temperature at 25 ± 1ºC and the relative humidity at 65 ± 5%. Nymph developmental time tended to be longer under shorter photophases (11 and 12 hL). The 14-hour photophase (long day) resulted in lower nymph mortality rates. Females maintained at 13 and 14 hL showed greater weight gain (1st-28th day) than females under 12 hL. D. melacanthus showed reproductive oligopause induced by short photophases, especially when exposed to 11 hL. Under 13 and 14 hL, 85% and 65% of females oviposited, respectively, in comparison to 10% and 15% of females ovipositing under 11 and 12 hL, respectively. Fecundity (number of egg masses and number of eggs/female) was greater in the longer than under the shorter photophases. Seasonal dimorphism induced by photoperiod was observed in D. melacanthus adults. Under short-day conditions (11 and 12 hL), adults showed short and rounded shoulder spines, grayish brown abdomen (mainly in 11 hL), high lipid contents, and lower percentage of mature reproductive organs. Under long-day conditions (13 and 14 hL), the stink bugs showed greatly developed shoulder spines, green abdomen, low lipid contents, and mature reproductive organs.

Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.

The main objective of this study was a bio-economic survey of artisanal fishing so as to compare average profit of the fishermen, in two different environments (reservoirs and river) and seasons (dry and rainy). To carry out financial comparisons of artisanal fisheries in Urubupungá Complex in the middle Paraná River (Brazil), three habitats were considered: I) Ilha Solteira and Jupiá reservoirs; II) the Paraná River between the Jupiá and Primavera dams; III) the Paraná River downstream from the Primavera dam. Data collection was done through questionnaires addressed to a total of 187 fishersmen; just 164 of the resulting interviews were considered valid. They were held in July 1998 (dry season) and February 1999 (rainy season). The daily average profit of the resevoir fisherman was R$ 13.19 during the dry and R$ 19.54 during the rainy season; R$ 4.10 and R$ 12.92 for fishermen located on the Paraná River between Jupiá and Primavera dam; and R$ 1.48 and R$ 23.01 for those located on the Paraná River below Primavera dam (R$ 1.00 = US$ 0.86 during the dry season; R$ 1.00 = US$ 0.52 during the rainy season). A linear model had been tried to explain the profit variable, in relation to those variables directly linked to fishing (e.g., as habitats; seasons, dry or rainy; gear used; days spent fishing) as well as several sociological variables (age, marital states, number of dependents, and education). However, due to large variability in profits, the proposed model only explained 48.4% of variability, and the only significant factors were education, type of gear, and covariant fishing days.

In this study we describe the ultrastructure of the endocrine cells observed in the midgut of M. quadrifasciata anthidioides. This bee has two types of endocrine cells, which are numerous on the posterior midgut region. Cells of the closed type are smaller and have irregular secretory granules with lower electrondensity than those of the open cell type. The open cell type has elongated mitochondria mainly on the basal area, where most of the secretory granules are also found. Besides the secretion granules and mitochondria, endocrine cells in this species have well-developed autophagic vacuoles and Golgi complex elements.

The presence of the marine leech, Stibarobdella loricata (Harding, 1924) (Hirudinea, Piscicolidae), is reported on the southern coast of Brazil, based on seven lots with 47 specimens, between 71 and 182 mm in total length, collected on the dorsal region of angel sharks, Squatina argentina (Marini, 1930); S. guggenheim Marini, 1936; S. punctata Marini, 1936 (Chondrichthyes, Squatinidae); and on the head of a sandtiger shark, Carcharias taurus Rafinesque, 1810 (Chondrichthyes, Carchariidae). This is the first record of S. loricata in the western Atlantic and of its parasitic association with S. argentina, S. guggenheim, S. punctata, and C. taurus.

The state of development of the internal reproductive organs of male and female Oebalus poecilus (Dallas) as well as the body fat amount in the abdominal cavity during hibernation, of individuals sampled in bamboo litter in Eldorado do Sul (30º02'S and 51°23'W), RS, Brazil was investigated. Females and males showed the abdominal cavity filled with body fat in the beginning of the hibernation phase. The decrease in fat reserve level occurred from August on for males and from October on for females. Ovaries and testis doubled in length and tripled in width from immature to the reproductive phase. Male sexual maturation occurred in the hibernation sites while for females it occurred later on outside of the sites. Reproductive organ immaturity and abdominal body fat hypertrophy characterized the diapause of O. poecilus.

In the present work we aimed to register the occurrence of galls, inductors, inquilines, and parasitoids in plants of three natural vegetation areas in Delfinópolis, MG, Brazil. Results obtained showed 22 types of galls collected from leaf, vein leaf, petioles, stem, and inflorescence of nineteen species belonging to fifteen distinct families. Concerning gall morphology, the following were collected: globoid, conicle, discoidal, fusiform, shell-shape, indefinite, and one substituition of an ovary by an immature. As principal inducers were found insects of the families Cecidomyiidae (Diptera), Psyllidae, and Diaspididae (Sternorrhyncha/Hemiptera). As parasitoids the most common are of the Chalcidoidea superfamily (Hymenoptera) and, as occasional inquilines, Polyxenidae (Diplopoda) and Psocodea (Psocoptera). The results of this study contribute to existing of knowledge host-plant diversity and gall-associated insects in rocky fields, cerrado, and gallery forests.

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The photodocumentation technique was used weekly to observe until the end of the regenerative process of eyes in three species of Dugesia. Morphometric data based on the measurement of 96 samples of the species: Dugesia tigrina, D. schubarti, and D. anderlani were analyzed A comparative analysis was made through graphic representation of statistical parameters of the following morphometric characters: the length of the transversal and longitudinal axes of the macula alba, pigment spot, and ocular opening. An interesting feature appeared in D. schubarti: the average of ocular opening during the regenerative process is bigger than in the original samples.

Longitudinal changes in composition, abundance, and distribution of copepods were studied at the transition zone of Paranapanema River-Jurumirim Reservoir (SP, Brazil). The interchange of biotic material between marginal lakes and the river system was also examined. Water samples were obtained from 6 stations along a stretch of 13 km of the Paranapanema River, from an upstream reach with high water velocity up to the river mouth into Jurumirim Reservoir. Two other sites in lateral lakes were also sampled. Nine copepod taxa were identified: 3 calanoids (Argyrodiaptomus furcatus Sars, Notodiaptomus iheringi Wright, and N. conifer Sars) and 6 cyclopoids (Eucyclops Claus, Microcyclops Claus, Mesocyclops longisetus Thiébaud, Thermocyclops decipiens Fischer, T. minutus Lowndes, and Paracyclops Claus). Harpacticoids were also collected. Calanoid and cyclopoid nauplii and copepodids, and harpacticoids were the most abundant organisms. In general, there was a longitudinal decrease in copepod abundance, whereas an increase was detected near the lakes. The abundance of most copepods was inversely correlated with current velocity and suspended solids. Higher abundance was observed in the river main course during the rainy season, during which there is a higher connectivity between the lakes and the main river. This promotes exportation of biologic material from marginal lakes to the river system, a biotic exchange reflecting the importance of marginal lakes to the river community structure.

The ultrastructure of the body tegument of Metamicrocotyla macracantha (Alexander, 1954) Koratha, 1955, parasite of Mugil liza from Brazil, was studied by transmission electron microscopy. The body tegument is composed of an external syncytial layer, musculature, and an inner layer containing tegumental cells. The syncytium consists of a matrix containing three types of body inclusions and mitochondria. The musculature is constituted of several layers of longitudinal and circular muscle fibers. The tegumental cells present a well-developed nucleus, cytoplasm filled with ribosomes, rough endoplasmatic reticulum and mitochondria, and characteristic organelles of tegumental cells.

Richness and diversity of ant species are related to environmental factors such as vegetation, soil, presence of heavy metals, and insecticides, which allow the use of the assemblage members as terrestrial indicators of environmental conservation status. This study presents the results of ground ants surveyed in Minas do Camaquã in the municipality of Caçapava do Sul (Camaquã Basin), State of Rio Grande do Sul. Collections were performed in four sites, with high levels of copper in the soil, three of which - a mine, a liquid reject, and a solid reject -, had sparse or no plant cover, and one site where Pinus has been used for rehabilitation. Parque das Guaritas was the control site, since it presented normal levels of copper and a dense savanna cover. For each site, three transect lines extending 100 m were draw, and at each 10 m sardine baits were distributed; after two hours the ants present were collected. Hand collections in all five sites were performed during one hour (capture effort). A total of 51 species belonging to 17 genera were collected. The control site was the richest in ant species (r = 45). Sites with high level of copper and poor plant cover presented the lowest richness: mine (r = 14), solid reject (r = 15), and liquid reject (r = 16). In contrast, the site planted with Pinus presented an increment in richness (r = 24) of ground-dwelling ants, suggesting a reahabilitation process.

Macroecological variables of Anuran species found in a local assemblage from Central Brazil (Silvânia, Goiás State) were linked to population dynamics statistics of these species. Geographical range size (GRS), body size, and species' midpoints were the macroecological variables investigated for those species found in the local assemblage and for all other species (105 in the total) found in the Cerrado biome. For each species found in the local assemblage, data on abundance was obtained. Using this data, local population variability as expressed by the coefficient of variation was estimated. Distribution of means, medians, maximum, variances, and skewness (g1), for both GRS and body size, estimated in the local assemblage were compared, using null models, with the data extracted from the overall Cerrado species pool. The results indicated a clear macroecological relationship between GRS and body size and a decrease in local abundance when distance between the locality analyzed and species midpoint increased. According to null models, both body size and GRS values measured in the local assemblage can be considered a random sample from the regional species pool (Cerrado region). Finally, a three-dimensional analysis using body size, GRS, and local population estimates (abundance and variability), indicated that less abundant and more fluctuating species fell near the lower boundary of the polygonal relationship between GRS and body size. Thus, macroecological results linked with local data on population dynamics supported the minimum viable population model.