When touched with a contact stimulus, 50% of adult Uloborus glomosus jumped from the web; 33% remained motionless; 13% moved to the edge of the web; and 4% shook the web. In a population of juveniles, 45% moved to the edge of the web; 27% jumped from the web; 24% shook the web; and 4% remained motionless. Adults with either stabilimenta or eggsac chains in their webs showed a tendency to shake their webs in the morning and move to the edge in the evening. Those without web structures jumped from their webs throughout the day. Juveniles with stabilimenta shook their webs in the afternoon; those without stabilimenta shook their webs in the evening. Adults aligned with web structures remained motionless when disturbed. Marked adults observed over the course of 4 weeks moved to the edge of the web or remained motionless when contacted in the mornings and jumped in the afternoons and evenings. During this time, the frequency of the jumping behavior increased. An adult U. glomosus jumped from its web in response to contact by a spider-hunting wasp. Other spiders tested with a contact stimulus and the combined visual and vibratory stimuli produced by a tethered wasp responded only to contact. Females tending their eggsac chains exhibited two types of defensive behaviors when either the parasitoid Arachnopteromalus dasys or spiderlings were placed on their eggsacs. They jerked their webs and swept the eggsacs with their long front legs. / Master of Science

Thesis (MSc. (Zoology)) --University of Limpopo, 2008 / Refer to document / National Research Foundation - Thuthuka programme

The potential relationship between riparian arachnids and aquatic insect productivity was assessed in forest streams throughout the central South Island of New Zealand. Initially, a survey was conducted of thirty seven, first-third order forest streams. Streams were selected to represent a range of benthic invertebrate standing crops (as a surrogate measure of "productivity") from Banks Peninsula streams with relatively high benthic invertebrate densities to acid mine drainage streams near Reefton that were almost devoid of aquatic life. At each site benthic invertebrate densities and biomass were measured in riffle habitats and adjacent gravel bars were sampled for terrestrial invertebrates. At a sub-set of 16 sites, a 20 metre longitudinal web-building spider survey was conducted along each bank of the stream. As an additional component, a 20 metre transect starting at the stream margin and running perpendicularly into the forest was used to survey the density of web-building spiders with increasing distance from the stream. Results from the survey of in-situ stream insect biomass and gravel bar invertebrates showed a strong relationship between aquatic insect biomass and the biomass of riparian arachnids (R2 = 0.42, P < 0.001) having accounted for potentially confounding factors such as stream size, elevation, substrate and disturbance. The 20 metre longitudinal survey showed that streams with the highest in-situ insect biomass had significantly higher densities of web-building spiders along their banks (R2 = 0.28, P < 0.05), having accounted for potential confounding variables of elevation, habitat architecture and stream and channel width. The stream to forest survey showed a strong exponential decay in web-building spider densities with increasing distance from the stream (R2 = 0.96, P < 0.0001). Regardless of stream productivity web-building spiders were most abundant at the stream margins and rapidly declined to very low densities 20 metres from the stream. In order to further test the relationship between riparian web-building spider densities and stream insect productivity, a stream fertilization experiment was conducted on six first-second order streams in the Maimai experimental catchment, Reefton. Three streams were enriched by the addition of a fertiliser solution mainly consisting of sodium nitrate for seven months, and the other three streams were used as controls. Water chemistry, benthic invertebrate communities, emerging aquatic adults, and the densities of web-building spiders along the stream corridor and in the forest were monitored in three seasons (spring, summer and autumn) over the course of the nutrient-addition. By the end of the experiment, conductivity was significantly higher in nutrient-addition streams than in the control streams (F = 80.5, P < 0.001), but chlorophyll concentrations showed no significant differences between treatments. Both benthic mayfly densities (F = 6.15, P < 0.05) and the biomass of adult aquatic dipterans (Chironomidae, Simuliidae) (F = 9.25, P < 0.01) were significantly higher in nutrient-addition streams in the last sampling round. Spiders recorded from intercept traps indicated that by the end of the experiment spider activity was significantly higher within 2.5 metres of the nutrient-addition streams (F = 5.70, P < 0.01). However, seasonal densities of web-building spiders along the stream margin and in the forest decreased with no significant differences observed between nutrient-addition and control streams. The results from these studies indicate that adult insects emerging from streams represent an important source of prey that could influence the biomass and abundance of riparian arachnids. Additionally, the results imply that stream productivity and size could mediate the strength of the interaction between riparian and stream habitats. Moreover, feedback mechanisms present in both systems could have implications for such interactions. The elevated densities of web-building spiders observed at the stream margin led to the proposal of the "Highway Robber" hypothesis. This hypothesis suggests that such higher densities of spiders are the result of increased insect activity along the stream corridor: the emergence of adult aquatic insects was predicted to vary less over temporal and spatial scales than that of terrestrial insects due to the poorly synchronized life histories in many New Zealand stream insects. I conclude by suggesting that there are numerous anthropocentric perturbations such as loss of heterogeneity, introduced species, pollution and habitat degradation that could undermine and decouple the intimate linkages between aquatic and terrestrial ecosystems.

O gênero Plesiopelma Pocock, 1901 é revisado taxonomicamente e realizada análise cladística de suas espécies. A matriz com 30 táxons terminais e 49 caracteres foi analisada com dois programas para reconstrução filogenética, considerando tanto caracteres aditivos como não-aditivos. As quatro análises apresentaram diferenças na topologia, porém três delas demonstram que Plesiopelma é um gênero monofilético. A diagnose e a distribuição geográfica das espécies são apresentadas. São consideradas válidas as espécies P. flavohirtum (Simon, 1889), P. semiaurantiacum (Simon, 1897),P. myodes Pocock, 1901, P. insulare (Mello-Leitão, 1923), P. physopus (Mello-Leitão, 1926), P. minense (Mello-Leitão, 1943) e P. simoni (Soares e Camargo, 1948). É proposta a sinonímia de P. rectimanum (Mello-Leitão, 1923) e P. longisternale (Schiapelli e Gerschman, 1942) com P. myodes. São reconhecidas seis espécies novas para o Brasil. É proposta a transferência de P. imperatrix Piza, 1976 para o gênero Megaphobema Pocock, 1901 e P. gertschi (Caporiacco, 1955) é considerada Incertae sedis. / The genus Plesiopelma Pocock, 1901 is taxonomically revised and a cladistic analysis of its species is done. The matrix with 30 terminal taxa and 49 characters was analysed with two programs for phylogenetic reconstruction. The four analyses showed different topologies on the internal group, however, three of them show Plesiopelma being a monophyletic genus. The diagnoses and geographic distribution of all species are presented. It is herein considered valid the species P. flavohirtum (Simon, 1889), P. semiaurantiacum (Simon, 1897), P. myodes Pocock, 1901, P. insulare (Mello-Leitão, 1923), P. physopus (Mello-Leitão, 1926), P. minense (Mello-Leitão, 1943) and P. simoni (Soares e Camargo, 1948). The species P. rectimanum (Mello-Leitão, 1923) and P. longisternale (Schiapelli & Gerschman, 1942) are considered junior-synonyms of P. myodes. It is recognized six new species from Brazil. It is proposed the transfer of P. imperatrix Piza, 1976 to Megaphobema Pocock, 1901 and P. gertschi (Caporiacco, 1955) is considered Incertae sedis.

O Brasil é o maior produtor mundial de citros, com aproximadamente 455 milhões de caixas por ano. No país os principais problemas da cultura estão relacionados a fitopatologias e ataques de fitófagos, que diminuem a produtividade e afetam os preços do produto no mercado. Nesse contexto, o controle desses insetos se faz necessário para que sejam evitadas perdas econômicas e produtivas. Assim, as aranhas surgem como potenciais agentes de controle, devido à estratégia trófica que adotam, sendo completamente dependentes da predação, auxiliando na regulação de espécies-praga em cultivos comerciais. O presente trabalho teve como finalidade lançar mão da análise dos isótopos estáveis 13C e 15N, para determinar as principais fontes de carbono e nível trófico das principais famílias e grupos de aranhas presentes em cultivos de citros no município de Gavião Peixoto - SP. Foram coletados 4.832 indivíduos, distribuídos em 17 famílias, das quais 12 eram comuns às duas áreas estudadas; as famílias foram classificas em sete guildas funcionais. Através análise dos isótopos 13C e 15N foi possível determinar o percentual de carbono dos citros presente na alimentação das principais famílias e grupos amostrados, além do nível trófico médio. Os resultados indicaram que as famílias diferem na dependência de teias alimentares baseadas nos citros. Além disso, os dados coletados sugerem que a estrutura do ambiente, a arquitetura vegetal, o estado fenológico dos citros, as práticas de manejo e variações sazonais do clima, podem ter sido os principais fatores de variação na abundância das famílias e dependência do carbono dos citros por parte das aranhas. Salticidae e Theridiidae foram as principais famílias amostradas, por apresentarem maior abundância relativa e estarem presentes ao longo de todo o período de coletas. / Brazil is the world largest citrus producer, with about 455 million boxes per year. In the country the main problems faced by the planters are related to phytopathologies and phytophagous attacks that reduce productivity and can affect the prices of the product in the market. In this scenario, the control of phytophagous is necessary to avoid economic and productivity losses. Thus, spiders populations emerge as a potential control agent, due to the trophic strategy, completely dependent upon predation, therefore assisting in the regulation of pest species in the field. This study aimed to determine, through the analysis of 13C and 15N isotopes, the main sources of carbon and the trophic level of the most abundant families of spiders collected in two citrus orchards in the municipality of Gavião Peixoto - SP. 4832 spiders distributed among 17 families were collected, of which 12 were common to the two studied areas. The families were assembled into 7 functional guilds. By analyzing the isotopes 13C and 15N it was possible to measure the percentage of carbon coming from the citrus, present in tissues of the main spider families and groups sampled, plus the average trophic level. The results indicated that families differ in dependence on food webs based on citrus. Furthermore, the data allow to hypothesize that the structure of the environment, architecture of the vegetation, phenological state of the plants, management practices and seasonal variations of the weather, may have been the main factors of variation in the abundance of families and dependence on citrus food webs by the spiders. Salticidae and Theridiidae were the main sampled families, due to their larger relative abundance and presence throughout the sampling period.

O veneno produzido pela aranha Phoneutria nigriventer causa priapismo. O pré-tratamento de camundongos com inibidores da Óxido nítrico-sintase, antes de se injetar a toxina, inibe este priapismo. A toxina causa ativação do gene c-fos no núcleo paraventricular do hipotálamo (NPV). Este estudo tem como objetivo ampliar os conhecimentos relacionados ao mecanismo da ereção peniana causada pela toxina Tx2-6. A toxina foi injetada no NPV e os resultados não mostraram o envolvimento direto do mesmo com o priapismo. Procuramos então avaliar se há aumento na produção de óxido nítrico (NO) quando o tecido é submetido à TX2-6 e o resultado foi negativo. Foram feitos também experimentos com animais que sofreram ablação cirúrgica bilateral dos nervos cavernosos. Estes, quando injetados com a toxina, tiveram ereção peniana, porém não apresentaram exposição total do pênis, possivelmente devido à fibrose causada pela denervação. Estes resultados nos levam a crer que a ereção causada pela toxina Tx2-6 pode não ser mediada pela produção de NO e não depende da inervação peniana. / The venom produced by Phoneutria nigriventer spider causes priapism. Mice pretreatment with Nitric oxide-synthase inhibitors, before injecting the toxin, inhibits the priapism. The toxin causes c-fos gene activation in paraventricular nucleus of hypothalamus (PVN). This study aims to widen some knowledge concerning penile erection mechanism caused by Tx2-6 toxin. The toxin was injected in the PVN and the results didnt show its direct relation with the priapism. We analyzed if there is any increase of nitric oxide (NO) production when the tissue is submitted to TX2-6 and the result was negative. Experiments were carried out on mice which suffered bilateral surgical ablation of the cavernosum nerves. When these animals were injected with the Tx2-6 toxin, there was penile erection. However, the erection of the denervation group didnt present total penis exposition possibly due to the fibrosis caused by the denervation. These results reveal that erection caused by Tx2-6 toxin might not be mediated by NO production and it does not depend on penile nerves.

Large volumes of antisera were generated against Apis melli/era venom with which to develop a novel, platform technology for the inexpensive production of anti venoms. The ovine sera contained high levels of specific antibodies which neutralised the myotoxic, phospholipase A2 and in vivo activities of the venom. Methods of processing the antisera to provide Fab or F(ab')2 were investigated. F(ab')2 was thought to be clinically advantageous and, by determining the conditions necessary for the preferential breakdown of Fc and serum components other than F(ab')2' it was possible to avoid salt precipitation. Diafiltration was then used to remove most of the unwanted small fragments and anion-exchange chromatography to remove any remaining acidic impurities such as pepsin and large aggregates. The F(ab')2 was -97% pure and the yield - 199 per L of serum. This is the first specific therapy for mass envenoming by European or Africanised bees. Spiders of the genus Latrodectus (black widows) are distributed widely and about 2,500 bites are reported annually in the USA. The neurotoxic effects of the venom were studied on the isolated phrenic nerve diaphragm preparation. Low venom concentrations (ImgIL) were stimulatory while high concentrations (IOmg/L) caused nerve blockade which was potentiated by increased calcium levels. Although effective, the Merck antivenom, which is unprocessed horse serum, causes unacceptable risks. The second purpose of this project was to prepare an improved Latrodectus spider antivenom using the new platform technology. Different immunisation schedules were studied to optimise the humoral immune response. Sheep immunised with 2mg La. hesperus venom produced the highest levels of specific antibodies as assessed by ELISA, using the isolated nerve diaphragm preparation or in vivo in mice. The new process provided a pure F(ab')2 antivenom retaining 78% of the original antisera ED so neutralising power and was - twice as effective as the Merck antivenom.

A monofilia da subfamília Cteninae é testada com uma análise cladística usando o método da parcimônia. O resultado da análise demonstra que a subfamília é polifilética como atualmente delimitada. A monofilia de Cteninae requer a exclusão do gênero Celaetycheus e de cinco espécies de Ctenus, C. anahitiformis, C. bulimus, C. inazensis, C. miserabilis e C. tarsalis. A subfamília é composta por Ctenus, gênero que contém a espécie-tipo da família, e pelos gêneros Africactenus, Amauropelma, Anahita, Centroctenus, Isoctenus, Ohvida, Parabatinga, Petaloctenus, Phoneutria, Thoriosa, Trogloctenus e pelo menos mais sete linhagens independentes. A subfamília Cteninae pode ser reconhecida por uma sinapomorfia não-ambígua: campo mediano do epígino protuberante. O clado Cteninae também é sustentado por cinco sinapomorfias ambíguas: êmbolo fixo por membrana, apófise média em forma de copo, condutor hialino, mais largo que longo, quatro dentes na retromargem da quelícera e quelícera com dentículos intermarginais. Apenas duas sinapomorfias descritas acima estão presentes em todas as espécies de Cteninae usadas na análise: o setor mediano do epígino protuberante e a apófise média em forma de copo. O gênero Ctenus, com maior número de espécies da família (cerca de 240), aparece como um grupo polifilético como atualmente delimitado. A monofilia de Ctenus requer a exclusão de 22 espécies usadas nesta análise. As 12 espécies que permanecem em Ctenus sensu estrito formam um clado sustentado por duas sinapomorfias nãoambíguas: campo mediano do epígino com região da abertura de copula projetada e abertura de copulação como um lobo. Alguns padrões evolutivos observados na análise são discutidos. O gênero Celaetycheus Simon é revisado e transferido para a subfamília Calocteninae com base nos resultados da análise cladística de Cteninae. A espécie-tipo, Celaetycheus flavostriatus Simon, é redescrita e oito espécies novas são descritas, todas coletadas no Estado da Bahia, Brasil: Celaetycheus sp. 1 de Uruçuca e Barro Preto; Celaetycheus sp. 2 de Mascote, Pau Brasil, Jussari e Camacan; Celaetycheus sp. 3 de Coaraci, Itagibá e Jequié; Celaetycheus sp. 4 de Prado e Itamarajú; Celaetycheus sp. 5 de Salvador, Mata de São João, Cachoeira e Cruz das Almas; Celaetycheus sp. 6 de Porto Seguro; Celaetycheus sp. 7 de Ilhéus e Uruçuca; Celaetycheus sp. 8 de Camacan. A espécie Celaetycheus modestus Bryant é transferida para o gênero Ohvida Polotow & Brescovit. Um mapa de distribuição das espécies é fornecido. / A cladistic analysis using the parcimony method is used to test the monophyly of the subfamily Cteninae. The results of the analysis indicate that the subfamily is poliphiletic as currently delimited. The monophyly of Cteninae requires the exclusion of the genus Celaetycheus and five Ctenus species, C. anahitiformis, C. bulimus, C. inazensis, C. miserabilis and C. tarsalis. The subfamily is composed by Ctenus, the genus which contain the type species of the family, and by the genera Africactenus, Amauropelma, Anahita, Centroctenus, Isoctenus, Ohvida, Parabatinga, Petaloctenus, Phoneutria, Thoriosa, Trogloctenus and at least more seven independent lineages. The subfamily Cteninae can be recognized by one non-ambiguous synapomorphy: swollen median field of the epigynum. The Cteninae clade is also supported by five ambiguous synapomophies: embolus fixed by membranous area, cup-shaped median apophysis, hyaline conductor wider than long, four teeth in the chelicerae retromargin and chelicerae with intermarginal denticles. Only two of the synapomorphies described above are present in all Cteninae species used in the analysis: swollen median field of the epigynum and cup-shaped median apophysis. The genus Ctenus, with the high number of species of the family (about 240), appears as a poliphylec group as currently delimited. The monophyly of Ctenus requires the exclusion of 22 species used in this analysis. The 12 species which remain in Ctenus sensu strict form a clade supported by two non-ambiguous synapomorphies: median field of the epigynum with area of the copulatory opening projected and copulatory opening as a lobe. Some evolutive patterns observed in the analysis are discussed. The genus Celaetycheus Simon is revised and trasferred to the subfamily Calocteninae with basis on the new results of the cladistic analysis of Cteninae. The type species, Celaetycheus flavostriatus Simon is redescribed and eight new species are described, all collected in the State of Bahia, Brazil: Celaetycheus sp. 1 from Uruçuca and Barro Preto; Celaetycheus sp. 2 from Mascote, Pau Brasil, Jussari and Camacan; Celaetycheus sp. 3 from Coaraci, Itagibá and Jequié; Celaetycheus sp. 4 from Prado and Itamarajú; Celaetycheus sp. 5 from Salvador, Mata de São João, Cachoeira and Cruz das Almas; Celaetycheus sp. 6 from Porto Seguro; Celaetycheus sp. 7 from Ilhéus and Uruçuca; Celaetycheus sp. 8 from Camacan. The species Celaetycheus modestus Bryant is transferred to Ohvida Polotow & Brescovit. A distribution map is provided.

The heterogeneity in species assemblages of epigeal spiders was studied in a natural forest and in a managed forest. Additionally the effects of small-scale microhabitat heterogeneity of managed and unmanaged forests were determined by analysing the spider assemblages of three different microhabitat structures (i. vegetation, ii. dead wood. iii. litter cover). The spider were collected in a block design by pitfall traps (n=72) in a 4-week interval. To reveal key environmental factors affecting the spider distribution abiotic and biotic habitat parameters (e.g. vegetation parameters, climate parameters, soil moisture) were assessed around each pitfall trap. A TWINSPAN analyses separated pitfall traps from the natural forest from traps of the managed forest. A subsequent discriminant analyses revealed that the temperature, the visible sky, the plant diversity and the mean diameter at breast height as key discriminant factors between the microhabitat groupings designated by the TWINSPAN analyses. Finally a Redundant analysis (RDA) was done revealing similar environmental factors responsible for the spider species distribution, as a good separation of the different forest types as well as the separation of the microhabitat groupings from the TWINSPAN. Overall the study revealed that the spider communities differed between the forest types as well as between the microhabitat structures and thus species distribution changed within a forest stand on a fine spatial scale. It was documented that the structure of managed forests affects the composition of spider assemblages compared to natural forests significantly and even small scale-heterogeneity seems to influence the spider species composition. / Um die Anpassungsfähigkeit von Organismen, bei sich ändernden Umweltbedingungen, sicher zu stellen, spielt die Erhaltung der Biologischen Vielfalt auf allen ökosystemaren Ebenen eine entscheidende Rolle. Eben diese Anpassungsfähigkeit kann durch waldbauliche Maßnahmen einschränkt werden, und zur Instabilität des Systems führen. Daher kommt der Untersuchung von aus der Nutzung genommenen Naturwaldzellen eine immer größere Bedeutung zu. Einerseits um die potentiell natürliche Diversität in Naturwäldern mit der in Wirtschaftswäldern zu vergleichen, andererseits um die ökologischen Zusammenhänge in einer natürlichen Waldentwicklung zu verstehen. Ziel diese Studie war es eben diese natürlichen Waldynamiken auf das Artengefüge von Spinnen (Araneae) zu untersuchen. Dabei sollte Mithilfe eines experimentellen Fangdesigns, auch der kleinräumige Einfluss von Strukturheterogenität untersucht werden.

Webs are fundamental to the ecology of Nephila clavipes, the golden orb-weaver spider, because they serve as sites for prey capture, reproduction, competition, predation, and parasitism. In addition to the presence of the female N. clavipes, males and kleptoparasites reside on the web in varying numbers. Webs are also found in clusters with conspecific females. Web site selection and length of web tenure is a behavioral decision vital to the spider’s fitness and the ecology of her species. I conducted a field census to quantify these factors and analyze their influence on web tenure, compare web ecology between a forest and non-forest habitat, as well as explain the significance of N. clavipes’ web as central to many interactions. Web tenure, as well, was influenced differently by the factors between both environments. In the forest habitat, increase in prey capture rate decreased web tenure and inclusion in cluster increased web tenure. In the non-forest habitat, only increase in spider size was related to increased web tenure. There were significant differences between the two habitats in the sizes of the female spider and quantity of males and kleptoparasites. Results also showed that spider size influenced quantity of males and web diameter influenced quantity of kleptoparasites. Explanation of these results can be attributed to the complex relationships among the variables and the consequences of living in habitats impacted by human occupation.