Biology and behaviour of the neotropical ant-mimicking spider Aphantochilus rogersi (Araneae: Aphantochilidae): nesting, maternal care and ontogeny of ant-hunting techniques

Aphantochilus rogersi is an ant-mimicking spider that preys exclusively on cephalotine ants. The spiders oviposit in close proximity to nests of the model ant Zacryptocerus pusillus, and emergent spiderlings tend to remain in the vicinity of natal egg sacs. Females of A. rogersi actively defend their egg sacs against approaching workers of Z. pusillus, but the latter may sometimes destroy the eggs. Feeding specialization on these ants is confirmed by more than 300 observations of young and adult A. rogersi carrying ant corpses in the held. Although A. rogersi possesses several behavioural traits which may reduce the risk of being injured by ants during subjugation, field and laboratory observations showed that social defence by Z. pusillus may cause mutilation to the spiders. Tests in captivity revealed an ontogenetic change in the prey-capture techniques employed by A. rogersi. Early-instar spiderlings can apparently only seize the ant's petiole tightly if they are able to approach the ant from the front. As the ant is paralysed, the spiderling positions itself vertically in relation to the substratum. Larger spiders, on the other hand, attack ants most frequently from behind, and seem better equipped to seize the ant's petiole firmly with their larger chelicerae. Owing to their greater strength, late-instar spiders are able to Lift the struggling ant aloft. The selection of a suitable oviposition site, the mother's ability to defend herself and the eggs from nearby ants, and the capacity to capture and subdue ants safely from emergence to maturity, are regarded as crucial traits inherent in the mimetic and feeding specialization by A. rogersi.

Bird species of black water inundation forests in the Jau National Park (Amazonas state, Brazil): their contribution to regional species richness

We compared the relative contribution of blackwater inundation forest (igapo) and unflooded (terra firme) forest for regional bird species diversity in the lower Rio Negro region. For analyses of habitat preference we used mist-net samples and an unpublished bird species check-list. The igapo forest had lower bird species diversity than the terra firme forest. However, some 14% of the forest bird species in the region are restricted to igapo forest. Species composition was found to be distinct between the understories of the two forest types. Common forest bird guilds in the Neotropics such as ant-following birds avoid igapo forest. The differential habitat selection among birds in the inundated and unflooded forest is likely to result from vegetation structure and biological interactions such as aggressive behaviour. Since the inundated forest has a typical biota, conservation efforts needs to be directed to protect these habitats. Unfortunately, inundation forests are threatened by several human actions, especially dam construction. The extent of protected areas in the Brazilian Amazon is insufficient for the adequate protection of the inundated habitats, because it includes only 3% of the total area.

Isolation and sequence determination of peptides in the venom of the spider wasp (Cyphononyx dorsalis) guided by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry

Micro-scale (sub-pmol) isolation and sequence determination of three peptides from the venom of the solitary spider wasp Cyphononyx dorsalis is described. We isolated two novel peptides Cd-125 and Cd-146 and a known peptide Thr(6)-bradykinin from only two venom sacs of solitary spider wasp Cyphononyx dorsalis without bioassay-guided fractionation. but instead guided by MALDI-TOF MS. The MALDI-TOF MS analysis of each fraction showed the purity and molecular weight of the components, which led to the isolation of the peptides virtually without loss of sample amount. The sequences of the novel peptides Cd-125 (Asp-Thr-Ala-Arg-Leu-Lys-Trp-His) and Cd-146 (Ser-Glu-Thr-Gly-Asn-Thr-Val-Thr-Val-Lys-Gly-Phe-Ser-Pro-Leu-Arg) were determined by Edman degradation together with mass spectrometry. and finally corroborated by solid-phase synthesis. The known peptide Thr(6)-bradykinin (Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg) was identified by comparison with the synthetic authentic specimen. This is the first example for any kinins to be found in Pompilidae wasp venoms. The procedure reported here can be applicable to studies on many other components of solitary wasp venoms with limited sample availability. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Conductive composites of natural rubber and carbon black for pressure sensors

Composites of natural rubber and carbon black have attracted great interest due to their technological applications. In this work natural rubber (NR) and carbon black (CB) were compounded, aiming the development of composites with good mechanical properties, processability and electrical conductivity for use as pressure sensors. The electrical conductivity changes from 10(-11) to 10(-2) S.cm(-1) depending on the percentage of CB in the composite. It was also observed that the conductivity varies reversibly and linearly with the applied pressure. The latter demonstrates that this material can be used as pressure sensors.

Structure determination of an organometallic 1-(diazenylaryl)ethanol: A novel toxin subclass from the web of the spider Nephila clavipes

A novel chemical subclass of toxin, [1-(3-diazenylphenyl) ethanol]iron, was identified among the compounds present in the web of the spider Nephila clavipes. This type of compound is not common among natural products, mainly in spider-venom toxins; it was shown to be a potent paralytic and/or lethal toxin applied by the spider over its web to ensure prey capture only by topical application. The structure was elucidated by means of ESI mass spectrometry, H-1-NMR spectroscopy, high-resolution (HR) mass spectrometry, and ICP spectrometry. The structure of [1-( 3-diazenylphenyl)ethanol] iron and the study of its insecticidal action may be used as a starting point for the development of new drugs for pest control in agriculture.

Isolation and chemical characterization of PwTx-II: A novel alkaloid toxin from the venom of the spider Parawixia bistriata (Araneidae, Araneae)

Brazil has many species of spiders belonging to Araneidae family however, very little is known about the composition, chemical structure and mechanisms of action of the main venom components of these spiders. The main objective of this work was to isolate and to perform the chemical characterization of a novel beta-carboline toxin from the venom of the spider Parawixia bistriata, a typical species of the Brazilian 'cerrado'. The toxin was purified by RP-HPLC and structurally elucidated by using a combination of different spectroscopic techniques (UV, ESI-MS/MS and H-1 NMR), which permitted the assignment of the molecular structure of a novel spider venom toxin, identified as 1-4-guanidinobutoxy-6-hydroxy-1,2,3,4-tetrahydro-beta-carboline, and referred to here as PwTx-II. This compound is toxic to insects (LD50 = 12 +/- 3 eta g/mg honeybee), neurotoxic, convulsive and lethal to rats (LD50 = 9.75 mg/kg of male Wistar rat). (c) 2005 Elsevier Ltd. All rights reserved.

Relative growth of spider crab Acanthonyx scutiformis (Dana, 1851) (Crustacea, Decapoda, Majidae)

The dimensions of chelar propodus and abdomen were utilized for the morphometric analysis about the relative growth studies of Acanthonyx scutiformis (Dana, 1851). A total of 297 specimens (114 males and 183 females), was collected in Ubatuba, State of São Paulo, Brazil. The animals were sexed and soarted to maturation phase (immature and mature). The following measurements were made: carapace (length and width), abdomen width and chelar propodus (length and height). In this study was applicated the power function (y= a.x(b)), in which the growth was considered positive allometric with isometric with b=1, and negative allometric with b<1. The alometry becomes isometric, when the results concerning immature and mature females and males are analysed. In the Brachyura male chelipeds are utilized in territorial defense, fight, display and courtship and female abdomens are utilized as a chamber that protect and incubate the eggs.

MOLECULAR DIAGNOSIS of LEISHMANIA AMAZONENSIS IN A CAPTIVE SPIDER MONKEY IN BAURU, São Paulo, BRAZIL

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

Acid Black 48 dye biosorption using Saccharomyces cerevisiae immobilized with treated sugarcane bagasse

The textile industry consumes large quantities of water and chemicals, especially in dyeing and finishing processes. Textile dye adsorption can be accomplished with natural or synthetic compounds. Cell immobilization using biomaterials allows the reduction of toxicity and mechanical resistance and opens spaces within the matrix for cell growth. The use of natural materials, such as sugarcane bagasse, is promising due to the low costs involved. The aim of the present study was to evaluate the use of sugarcane bagasse treated with either polyethyleneimine (PEI), NaOH or distilled water in the cell immobilization of Saccharomyces cerevisiae for textile dye removal. Three different adsorption tests were conducted: treated sugarcane bagasse alone, free yeast cells and bagasse-immobilized yeast cells. Yeast immobilization was 31.34% with PEI-treated bagasse, 8.56% with distilled water and 22.54% with NaOH. PEI-treated bagasse exhibited the best removal rates of the dye at all pH values studied (2.50, 4.50 and 6.50). The best Acid Black 48 adsorption rates were obtained with use of free yeast cells. At pH 2.50, 1 mg of free yeast cells was able to remove 5488.49 g of the dye. The lowest adsorption capacity rates were obtained using treated bagasse alone. However, the use of bagasse-immobilized cells increased adsorption efficiency from 20 to 40%. The use of immobilized cells in textile dye removal is very attractive due to adsorbed dye precipitation, which eliminates the industrial need for centrifugation processes. Dye adsorption using only yeast cells or sugarcane bagasse requires separation methods.

Size distribution and sex ratio in the spider crab Epialtus brasiliensis (Dana 1852) associated with seaweed on a rocky shore in southeastern Brazil (Crustacea, Decapoda, Brachyura, Majoidea, Epialtidae).

This study analyzed a population of the spider crab Epialtus brasiliensis, in regard to its size distribution, sex ratio and Sexual maturity. The study was conducted on a rocky shore in the Ubatuba region, state of Silo Paulo, Brazil, where a wide strip of algae covers the intertidal zone. A total of 378 specimens were obtained: 200 males (128 juvenile and 72 adult crabs) and 178 females (46 juveniles and 132 adults). Their Sizes ranged from 3.4 to 16.7 mm carapace length (CL). Taking into account that the pubertal and terminal molts are coincident in majid crabs, the maximum sizes attained by males and females are especially dependent on the factors that influence sexual maturity, mainly food resources, temperature and intraspecific competition. Males of E. brasiliensis occurred in all size classes, whereas females occurred only as far the 10th size class (12-13 min CL). file total sex ratio did not differ statistically from 1 : 1, but when the juvenile and adult specimens were analyzed separately the differences between sexes were significantly different, with higher proportions of immature males and mature females. The CL50 calculated for males and females was 10.4, and 6.9 min CL, respectively. Thus, males reach their sexual maturity at a larger size than females. This feature may be important for the reproductive strategy of this species, because larger males probably have greater reproductive Success.

Plant glandular trichomes mediate protective mutualism in a spider-plant system

1. Although several species of Peucetia (Oxyopidae) live strictly in association with plants bearing glandular trichomes worldwide, to date little is known about whether these associations are mutualistic.2. In this study we manipulated the presence of Peucetia flava on the glandular plant Rhynchanthera dichotoma in the rainy and post-rain season, to test the strength of its effects on leaf, bud, and flower damage and plant reproductive output. In addition, we ran independent field experiments to examine whether these sticky structures improve spider fidelity to plants.3. Peucetia suppressed some species of foliar phytophages, but not others. Although spiders have reduced levels of leaf herbivory, this phenomenon was temporally conditional, i.e. occurred only in the post-rain but not in the rainy season. Floral herbivory was also reduced in the presence of spiders, but these predators did not affect plant fitness components.4. Plants that had their glandular trichomes removed retained fewer insects than those bearing such structures. Spiders remained longer on plants with glandular trichomes than on plants in which these structures had been removed. Isotopic analyses showed that spiders that fed on live and dead labelled flies adhered to the glandular hairs in similar proportions.5. Spiders incurred no costs to the plants, but can potentially increase individual plant fitness by reducing damage to reproductive tissues. Temporal conditionality probably occurred because plant productivity exceeded herbivore consumption, thus dampening top-down effects. Specialisation to live on glandular plants may have favoured scavenging behaviour in Peucetia, possibly an adaptation to periods of food scarcity.

Spider assemblages in widely-separated patches of cerrado in São Paulo State, Brazil.

Brazilian cerrado is a biologically-rich, poorly understood, yet rapidly disappearing habitat. Composition of the spider assemblages from areas of cerrado from three separate sites in the State of São Paulo, Brazil were sampled by beating the canopies and adjacent shrubs of three Myrcia (Myrtaceae; "myrtle") tree species. These produced a total of 859 spiders 'belonging to 21 families and 75 species. The most undisturbed and densest cerrado habitat had the largest number and greatest diversity of spider species, encompassing stalkers, ambushers, space web-weavers, and foliage runners. The other two areas were dominated by foliage runners. Spider distribution in this natural and complex habitat was evaluated by classifying the samples into 12 habitat/microhabitat groups according to local of the patch, tree species, and microhabitat (target tree or adjacent shrub). Correspondence analysis was used for ordination of species and groups based on their abundance. Environmental factors such as patches type (p=0.027) and plant species (p=0.046) had significant effects in explaining the ordination. Canonical correspondence analysis was applied for relating the patterns in species richness and/or abundance to the significant environmental factors. A comparison of the results showed that the family composition among the patches is rather similar, and there is a tendency of spiders species overlap an interregional level (patches effect, p=0.027). However, the most similar spider assemblages living on woody vegetation occurred in Myrcia venulosa and Myrcia guianensis at São Carlos and Pirassununga, demonstrating an interregional similarity (plant species effect, p=0.046) that indicates an association between spiders and particular vegetation.