Nanismo em machos não é regra em aranhas oonopidae (Arthropoda, Arachnida) / Male dwarfism is not the rule in oonopidae spiders (Arthropoda, Arachnida)

Aranhas apresentam um característico dimorfismo sexual em relação ao seu tamanho corporal. Ao contrário da maioria das espécies animais, aranhas machos podem ser várias vezes menores que as fêmeas. Entretanto, pouco se sabe se há a prevalência dessa dicotomia morfológica entre sexos de espécies com tamanhos reduzidos – como em Oonopidae spp., que tem o tamanho em torno de 3 mm. Aqui, nós investigamos se existe diferença no tamanho entre machos e fêmeas de cinco espécies de Onoopidae. As aranhas foram  coletadas na Caatinga, Cerrado e Mata Atlântica. Em cada indivíduo medimos: comprimento total do corpo; comprimento prossomal; largura prossomal; altura prossomal e achatamento. Encontramos que nas espécies avaliadas, não houve diferença das métricas corporais entre os sexos,  contrariando o esperado para maioria das aranhas. É possível que, devido ao tamanho naturalmente reduzido dos indivíduos dessa família, as forças de seleção morfológicas presentes em outras aranhas não atuem sobre Oonopide. Isso implica que os comportamentos e mecanismos de seleção sexual envolvendo aspectos de tamanho, presentes em outros grupos de aranhas, devem atuar distintamente em Oonopidae. Este trabalho traz uma novidade para a biologia de aranhas e abre caminho para questionamentos sobre a relação entre machos e fêmeas nestes artrópodes

The use of tympanic arena as an alternative for behavioral vibroacoustic essays in termites (Blattodea: Isoptera).

In termites, substrate-borne vibrations play an important role in communication among nestmates. The adaptive significance of such an ability has led to an ever-increasing number of studies aimed at improving knowledge on vibroacoustic communication in these insects. Such studies are commonly carried out in laboratory arenas consisting of Petri dishes made of plastic or glass. However, the rigidness of such materials may limit the transmission of vibrational waves impairing accurate records of the feeble vibrations produced by termites. This is one of the reasons why such experiments must be carried out under strictly controlled conditions, using extremely sensitive equipment, usually connected to amplifiers. If, instead, arenas bear a flexible floor (hence simulating a tympanum), vibrations might not be dampened or even easily amplified, thereby overcoming the need for such a specialized setup. Here we test such a hypothesis, using an accelerometer to measure and record vibrations whose intensity was tailored to mimic the feeble vibrations of a small termite species, Constrictotermes cyphergaster. Results support the notion that tympanic arenas portray such vibrations far more accurately than arenas made of plastic or glass. We hence recommend this type of arena as a cheap, albeit accurate, alternative in studies of vibroacoustic behaviors of termites and other insects of comparable size, especially in situations where noise is minimally controlled. These arenas, then, can be useful in conducting such studies just after termite collection in remote regions where well-equipped labs are not available. In doing so, we minimize the stress involved in transporting termites over long distances.

Os múltiplos usos das fezes pelos cupins (Blattodea: Isoptera)

As fezes são notoriamente um tópico desagradável para a maioria das pessoas. Entretanto, elas estão presentes no dia a dia de todos os animais e exercem funções muito além da excreção. Embora existam diversos exemplos de uso das fezes pelos animais, raros são os casos em que esses usos envol- vam as fezes de conspecı́ficos. Isso porque estas fezes podem representar um alto risco de infecção de patógenos, já que nelas, patógenos podem se desenvolver. Apresentamos neste trabalho uma revisão investigando os usos das fezes pelos animais e em especı́fico o caso dos cupins que são um dos raros grupos de animais que passam a vida em contato direto com a próprias fezes. O uso das fezes pelos cupins vale-se principalmente devido a ação dos microorganismos ali residentes, e foi se incrementando ao longo da evolução das linhagens de cupins. Tamanha relevância dessa massa fecal presente nos ninhos dos cupins, que ela é atualmente considerada a resistência estendida à doenças desses indivı́duos, como já demonstrado para Coptotermes formo- sanus por Chouvenc et al. (2013). No interior dos ninhos dessa espécie há uma massa composta por fezes e madeira triturada, onde vivem micróbios que agem no controle de patógenos dos cupins. Aqui, apresentamos também um trabalho empı́rico onde investigamos os mecanismos por trás desta resistência estendida. Verificamos se os patógenos poderiam ser impedidos de se desen- volver (i) por efeito de exclusão competitiva promovida pelos microorganismos benéficos, ou (ii) por um efeito de supressão direta oriundo de substâncias presentes na massa fecal, sejam estas substâncias liberados pelos microorganismos benéficos ou pelo metabolismo dos próprios cupins. Usamos a massa fecal de ninhos Cornitermes cumulans para avaliar seu efeito na sobrevivência desses cupins expostos à infecção de um fungo patogênico. Além disso, usamos essa massa fecal com e sem a supressão de microorganismos para investigar se eles afetam a germinação do termitopatógeno. Verificamos que a massa fecal não impede a infecção patogênica e consequente surgimento de doenças no corpo dos cupins, mas diminui a reprodução do patógeno. E esse efeito é devido nã somente aos microorganismos da massa fecal, mas também à massa fecal em si. Assim, esses resultados demonstram que a massa fecal de alguns cupins não atua aumentando a resistência a doenças diretamente nos indivı́duos, mas pode contribuir para sua saúde geral. Mais que isso, a massa fecal prejudica o desenvolvimento dos patógenos no ninho, atuando assim como uma agente profilático para a colônia, mesmo se os microorganismos benéficos nela residentes forem eliminados. Palavras-chave: Entomopatógeno. Infecção. Insetos. Microorganismos. Solo.Feces are notoriously an unpleasant topic for most people. However, they are present in the daily lives of all animals and perform functions far beyond ex- cretion. Although there are several examples of the use of feces by animals, there are rare cases in which these uses involve conspecific feces. It is because these feces can represent a high risk of infection, since pathogens can grow on them. We present here a review investigating the uses of feces by animals and especially for the case of termites, which are one of the rare groups of animals that spend their lives in direct contact with their own feces. We found that the use of feces by termites is mainly due to the action of microorganisms residing there, and it was increased over the evolution of termites lineages. Such is the relevance of the fecal mass in termite nest, that it is currently considered to pose extended resistance to diseases, as already demonstrated for C. formosanus by Chouvenc et al. (2013). Inside the nests of this species, there is a mass composed of feces and crushed wood, where live the microbes that control pathogens of termites. Here, we present an empirical work where we investigate the mechanisms behind such an extended disease resistance. We verified whether pathogens would be impaired (i) by competitive exclusion from beneficial microorganisms, or (ii) by direct supression originated from substances present in the fecal mass, be those liberated from microorganisms or from termite metabolism itself. We used the fecal mass of nests C. cumu- lans to evaluate its effect on the survival of these termites exposed to fugal pathogenic infection. Besides, we use this fecal mass with and without the suppression of microorganisms to investigate whether they affect the germination of termitopathogens. We found that the fecal mass does not prevent pathogenic infection and the consequent emergence of diseases in the body of termites, but it reduces the reproduction of the pathogen. And this effect is not only due to the microorganisms in the fecal mass, but also to the some yet unknown component of the fecal mass. Thus, these results demonstrate that the fecal mass of some termites does not act to increase resistance to disease in individuals themselves, but it can contribute to their overall health. Mo- reover, it impairs the development of pathogens in the nest, thus acting as a prophylactic agent for the colony, even if the beneficial microorganisms therein resident would be elliminated. Keywords: Entomopathogen. Infection. Insects. Microorganisms. Soil

Determinants of distribution and morphology of tropical forest soil spiders

As condições e recursos de um habitat são os fatores que frequentemente demonstram efeitos na distribuição e atuam como pressão de seleção sobre as espécies. Esses fatores são mais estudados em pequena escala geográfica e limitados a determinadas espécies ou ambientes. Determinar os fatores que predizem a riqueza e abundância das espécies em larga escala geográfica e para várias espécies, é um dos grandes desafios da ecologia. Este conhecimento se faz cada vez mais urgente frente às ameaças à conservação da biodiversidade em refúgios da biodiversidade, como as florestas tropicais, que estão sofrendo cada vez mais com a ação antrópica. Neste estudo investigamos quais fatores, em escala geográfica, predizem a riqueza e abundância de aranhas de solo. Além disso, testamos se o hábitat atua como pressão seletiva, favorecendo morfologias mais achatadas de aranhas que se locomovem no interior, comparadas às que se locomovem sobre a serapilheira. Nossa hipótese é que as condições são mais importantes para explicar a riqueza e abundância desses indivíduos do que os recursos, por serem precursores dos fatores bióticos. Entre as variáveis de condições, antecipamos que a altura da serapilheira seria a característica de hábitat mais importante para explicar a riqueza e abundância de aranhas de solo. Encontramos que apenas uma condição, a profundidade da serapilheira, explicou a riqueza e abundância de aranhas, o que corroborou as duas hipóteses propostas. Além da distribuição dessas aranhas, investigamos também se a serapilheira além de atuar como determinante na distribuição de aranhas de solo, ela exerce pressão na morfologia desses organismos. Nossas hipóteses para isso é que aranhas da família Oonopidae, que vivem dentro da serapilheira, possuem maior achatamento dorsoventral do que aranhas da família Ctenidae e zoodariidae que vivem sobre a serapilheira. Também que o achatamento dorsoventral dos indivíduos das famílias Oonopidae pode ser influenciado de acordo com o nível de compactação da serapilheira. Encontramos que os indivíduos das famílias Oonopidae possuem maior achatamento dorsoventral do que indivíduos da família Ctenidae e Zodariidae. Entretanto, esse achatamento dorsoventral dos indivíduos de Oonopidae não é influenciado pelos diferentes níveis de compactação da serapilheira. Concluímos que a serapilheira é uma condição que propicia não só recursos importantes para as aranhas de solo, como disponibilidade de alimento, mas também outras condições como seus microclimas. Por isso, a serapilheira tem importância na distribuição das aranhas de solo em macroescala geográfica. E talvez por isso exerce pressão de seleção na morfologia das famílias que vivem dentro da serapilheira, selecionando tamanhos mais achatados que permitem melhor manobrabilidade dos organismos entre os diferentes níveis de compactação dos seus micro-habitats.The conditions and habitat resources are factors that often show effects on the distribution and act as selection pressure on the species. These factors are most studied in small geographical scales and limited cases of species and environments. Determine the factors that predict the richness and abundance of species on a large geographic scale and multi-species, it is one of the great challenges of ecology. These knowledge is increasingly urgent threats front of biodiversity conservation in havens of biodiversity, such as tropical forests, which are suffering increasingly with anthropic action. We investigated what factors in large scale, can predict the richness and abundance of soil spiders in 16 forest environments in Brazil. In addition, we tested the litter acts as a selective pressure by selecting different morphologies of these spiders. Our hypothesis is that the conditions are more important to explain the richness and abundance of these individuals than the resources, because they are precursors of biotic factors. And that between the conditions, the height of the litter better explain the richness and abundance of soil spiders. We found only one condition, the depth of litter, he explained the richness and abundance of spiders, which corroborated the two hypotheses proposed. In addition to the distribution of these spiders, also investigated the litter as well as acting as a determinant in the distribution of soil spiders, it exerts pressure on the morphology of these organisms. Our hypothesis for this is that the spider’s Oonopidae family living within the litter, have a higher dorsoventral flattening than Ctenidae and Zodariidae families of spiders living on the litter. In addition, the dorsoventral flattening of individuals of Oonopidae family can be influenced according to the compression level of litter. We found that individuals of Oonopidae family have higher dorsoventral flattening of individuals of Ctenidaeand Zodariidae families. However, this dorsoventral flattening of individuals of Oonopidae and Zodariidae is not influenced by the different levels of compression of litter. We conclude that litter is a condition that not only provides important resources for soil spiders as food availability, but also other conditions as their microclimates. Therefore, the litter is important in the distribution of soil spiders macro geographic scale. Maybe because it, the litter exerts selection pressure on the morphology of families living within the litter, selecting flatter sizes that enable better handling of organisms between the different levels of compression of their microhabitats.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Attack behavior of two wasp species of the Polysphincta genus group (Hymenoptera, Ichneumonidae) on their Orb-Weaver Spider Hosts (Araneae, Araneidae)

Species in the Polysphincta genus group, as far as is known, are exclusively koinobiont ectoparasitoids of spiders. These wasps attack their hosts, inflicting a temporary paralysis, and then lay one egg on the host’s abdomen or prosoma. Parasitoid attack behavior is highly variable among species, including occasions where the wasp darts directly and holds the spider, as well as instances involving complex behavioral sequences. In the present study, we describe the attack behavior of Polysphincta sp. nr. purcelli and P. janzeni on Cyclosa fililineata and C. morretes, respectively. All attacks occurred at night. Initially, the female wasp landed on the web hub at the position occupied by the spider, with the spider always escaping from this initial attack. Subsequently, the wasp waited for up to 14 h at the web hub for the spider’s return. The wasp then inserted its ovipositor into the mouth of the spider, after which the spider became paralyzed and remained motionless for at least 30 min. The wasp laid one egg on the surface of the host’s abdomen and remained on the web for at least 1 h thereafter. The lie-in-wait and attack only after the return of the host to the web hub, as well as the permanence of the wasp on the web after the attack are not frequent behaviors described for polysphinctines. Behavioral idiosyncrasies, such as those observed here, are common among polysphinctines, suggesting a high level of specific adaptive matching of polysphinctine parasitoid behavior to their hosts’ biological characteristics

Host behavioural manipulation of two orb-weaver spiders by parasitoid wasps

Parasitic infection or tissue consumption by parasitoids typically leads to several phenotypic alterations in hosts, including distinct changes in behavioural, morphological, or life history traits. Some of these changes may not result solely from host responses, but actively induced changes by parasites/parasitoids to manipulate the host to acquire some benefit (e.g. parasite/parasitoid survivorship or dispersal ability). Field experiments investigating the effects of host behavioural alterations on parasite or parasitoid survivorship and the mechanisms involved in these changes are important for confirmation of behavioural manipulation. In the present study, we examined web design modification in the host spider species Cyclosa fililineata and Cyclosa morretes, which are attacked by the polysphinctine ectoparasitoid wasps Polysphincta sp. nr. purcelli and Polysphincta janzeni, respectively. We tested whether changes in orb spider web design (1) result from nutritional restrictions imposed by parasitoids and (2) increase the chances of adult wasp emergence from the cocoon. Furthermore, we describe changes in web design consistent with parasitoid larval development. Results, for both spider species, showed that web design modifications occurred only during the night preceding host spider death, and that modifications involved a reduction in the number of spirals and radii of orb webs. Food restriction did not generate web design modification, suggesting that observed changes in host behaviour resulted from direct actions of parasitoid larvae rather than as a by-product of nutritional deficiencies. Rain events were the major factor causing web rupture and subsequent parasitoid mortality. Modifications in web design reduced the frequency of web ruptures, increasing parasitoid adult emergence, and thus survivorship probability, during the pupal stage. These results confirm that web modifications by spiders are adaptive to parasitoid wasps

The use of tympanic arenas to improve accuracy in vibroacoustic bioassays using termites (Blattodea: Isoptera)

<p>Termites communicate, make foraging decisions and detect enemies via substrate-borne vibrations.  The adaptive significance of such an ability has led to an ever increasing number of studies aimed at improving knowledge on vibroacoustic communication in these insects. Such studies are commonly carried out in laboratory arenas consisting of Petri dishes made of plastic or glass. However, the rigidness of such materials may limit the transmission of vibrational waves impairing accurate records of the feeble vibrations produced by termites. It follows that arenas bearing a flexible floor (hence simulating a drum or a tympanum) would stand as a suitable alternative to minimize interferences on such vibrations, thereby producing cleaner and finely detailed datasets. Here we test such a hypothesis, using an accelerometer to measure and record vibrations whose intensity was tailored to mimic the feeble vibrations of a small termite species, \textit{Constrictormes cyphergaster}. Results support the notion that tympanic arenas portray such vibrations more authentically than arenas made of plastic or glass. We hence recommend this type of arena to be used in studies of vibroacoustic behaviors of termites and other insects of comparable size. Funding: CNPq.</p

The use of tympanic arena as an alternative for behavioral vibroacoustic essays in termites (Blattodea: Isoptera) Lívia Nunes, Federal University of Viçosa

<p>In termites, substrate-borne vibrations play an important role in communication among nestmates. The adaptive significance of such an ability has led to an ever increasing number of studies aimed at improving knowledge on vibroacoustic communication in these insects. Such studies are commonly carried out in laboratory arenas consisting of Petri dishes made of plastic or glass. However, the rigidness of such materials may limit the transmission of vibrational waves impairing accurate records of the feeble vibrations produced by termites. This is one the reasons why such experiments must be carried out under strictly controlled conditions, using extremely sensitive equipment, usually connected to amplifiers. If, instead, arenas bear a flexible floor (hence simulating a tympanum), vibrations might be not dampened or even easily amplified, thereby overcoming the need for such a specialized setup. Here we test such a hypothesis, using an accelerometer to measure and record vibrations whose intensity was tailored to mimic the feeble vibrations of a small termite species, <em>Constrictormes</em><em> cyphergaster.</em> Results support the notion that tympanic arenas portray such vibrations far more accurately than arenas made of plastic or glass. This type of arena as a cheap, albeit accurate, alternative in studies of vibroacoustic behaviors of termites and other insects of comparable size especially in situations where noise is minimally controlled. These arenas, then, can be useful in conducting such studies just after termite collection in remote regions where well-equipped labs are not available. In doing so, we minimize the stress involved in transporting termites over long distances. Funding: CNPq.</p

Núcleos de Ensino da Unesp: artigos 2013: volume 2: metodologias de ensino e a apropriação de conhecimento pelos alunos

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

Núcleos de Ensino da Unesp: artigos 2013: volume 2: metodologias de ensino e a apropriação de conhecimento pelos alunos

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