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1.
Naturwissenschaften ; 111(1): 7, 2024 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-38315245

RESUMO

Individuals can experience accentuated disputes for resources when living with many conspecifics, even in situations in which cooperative behaviors assure benefits associated with an increase in the frequency of food acquisition and in diet breadth. Thus, intraspecific competition may exert a significant selective pressure on social animals. Theoretical models suggest that females of social species could improve their fitness by producing relatively large offspring, since body size can provide competitive advantages during foraging activities. As female reserves are limited, the production of large offspring would occur at the expense of their number. Using five Anelosimus (Araneae, Theridiidae) species, we assessed whether the social ones produce fewer and larger eggs than the subsocials. In addition, we tested the effect of female size on the adoption of each particular reproductive strategy. Small females could hypothetically invest in producing large offspring since they cannot produce as many offspring as large females. Our results suggested that, indeed, sociality influences reproductive strategies. Females of social species produced fewer and larger offspring than females of subsocial species. Subsociality, in turn, would benefit the production of many small spiderlings, possibly because a large number of siblings is important to maintain and expand new webs and to subdue prey during their initial instars. Our results also indicated that large females produce more eggs without necessarily reduce their sizes. We discussed how the costs and benefits of group living may influence reproductive strategies.


Assuntos
Reprodução , Aranhas , Humanos , Animais , Feminino , Comportamento Social , Tamanho Corporal
2.
Ecol Lett ; 24(5): 1089-1102, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33617134

RESUMO

Despite the important roles of assortative mating for understanding evolutionary processes, our knowledge on the variation in assortative mating across populations and breeding periods has been overshadowed by the greater attention given to general patterns. Obtaining data on mating pairs are difficult for most species; therefore, researchers often group data from different populations or breeding periods, which can increase positive biases in detecting and estimating assortative mating. We used a meta-analytic approach to investigate the biases caused by spatially or temporally pooling data and the assortative mating consistency across populations and breeding periods. We describe assortative mating patterns across and within animal taxa. We performed a systematic review to search studies reporting measures of size-assortative mating (SAM). Grouping data from multiple populations and seasons incurred positive biases. Overall, assortative mating moderately exhibited low repeatability in space and time, but it was inconsistent for most taxa. After excluding pooled measures, the average estimate for assortative mating was moderate and positive. Thus, our findings demonstrate that pooling data can produce misleading results. We also highlight the importance of further investigation of hypotheses that explain spatial and temporal variation in assortative mating, after its detection. Our study reinforces the significance of investigating mating patterns at various spatial and temporal scales before drawing broad conclusions.


Assuntos
Preferência de Acasalamento Animal , Animais , Viés , Evolução Biológica , Reprodução , Estações do Ano
3.
Zootaxa ; 4750(2): zootaxa.4750.2.5, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32230474

RESUMO

Craspedisia cornuta (Keyserling, 1891), is redescribed on the basis of SEM data after more than fifty years after its last records. We also provide information on its natural history. SEM images for the proboscis, ventral plates of abdomen and male palp and epigynal plate are provided. Data on natural history using specimens collected in the Serra do Japi, from the state of São Paulo were analyzed and presented for the first time for this little-known species of Pholcommatinae theridiid spider.


Assuntos
Aranhas , Distribuição Animal , Animais , Brasil , Masculino
4.
Zootaxa, v. 4750, n. 2, p. 211-224, mar. 2020
Artigo em Inglês | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP | ID: bud-2986

RESUMO

Craspedisia cornuta (Keyserling, 1891), is redescribed on the basis of SEM data after more than fifty years after its last records. We also provide information on its natural history. SEM images for the proboscis, ventral plates of abdomen and male palp and epigynal plate are provided. Data on natural history using specimens collected in the Serra do Japi, from the state of São Paulo were analyzed and presented for the first time for this little-known species of Pholcommatinae theridiid spider.

5.
Zootaxa ; 4750(2): 211–224, 2020.
Artigo em Inglês | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP | ID: but-ib17562

RESUMO

Craspedisia cornuta (Keyserling, 1891), is redescribed on the basis of SEM data after more than fifty years after its last records. We also provide information on its natural history. SEM images for the proboscis, ventral plates of abdomen and male palp and epigynal plate are provided. Data on natural history using specimens collected in the Serra do Japi, from the state of São Paulo were analyzed and presented for the first time for this little-known species of Pholcommatinae theridiid spider.

6.
PLoS One ; 14(10): e0213887, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31577810

RESUMO

Niche theory suggests that the coexistence of ecologically similar species in the same site requires some form of resource partitioning that reduces or avoids interspecific competition. Here, from July 2013 to December 2015, we investigated spatial niche differentiation at three different scales of two sympatric congeneric spiders, Peucetia rubrolineata and P. flava, along an altitudinal gradient in shaded and open areas in an Atlantic forest in Serra do Japi, SP, Brazil. These spiders are peculiar in that they present an exclusive association with the plant Trichogoniopsis adenantha (Asteraceae). In theory, the coexistence of two Peucetia species could be explained by: (1) microhabitat segregation with individuals from different species occupying different parts of the same plants; (2) mesohabitat segregation with different species using plant in different environments; (3) macrohabitat segregation, where different species would not co-occur along the altitudinal gradient. With respect to micro-habitat use, in both species, different instars used different plant parts, while the same instars of both species used the same type of substrate. However, the two Peucetia species segregated by meso-habitat type, with P. rubrolineata preferring T. adenantha plants in shaded areas and P. flava preferring those in open areas. Our results support the hypothesis of niche partitioning begetting diversity, and highlight the importance of analyzing habitat use at multiple scales to understand mechanisms related to coexistence.


Assuntos
Asteraceae , Florestas , Aranhas/fisiologia , Simpatria/fisiologia , Animais , Brasil
7.
J Hymenopt Res, v. 66, p. 15-21, 2018
Artigo em Inglês | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP | ID: bud-2594

RESUMO

Epipompilus Kohl comprises 52 species of wasps that are parasitoids of spiders; 16 species occur in the Neotropical region and 36 species occur in the Australian region. The biological knowledge of this genus is limited and its interactions and host spiders are still incipient. Here, we report some behavioural and biological characteristics of E. excelsus, a parasitoid of the tube-dwelling spider Ariadna mollis. We observed an E. excelsus female attacking an adult female of A. mollis in São Paulo, Brazil. We photographed daily the larval development of the wasp, from the egg stage to adult emergence. The entire developmental cycle of the wasp took 24 days. This period was shorter than the developmental periods of wasps belonging to other genera of Pompilidae. Although all species within Pompilidae use spiders as host, they present great behavioural diversity, characterized by different ethological sequences. In conclusion, this study demonstrated that the Neotropical species of Epipompilus exhibit biological characteristics similar to the Australian species, acting as a koinobiont ectoparasitoid, but displays differences in larval morphology. Studies on other species could elucidate the extent of these differences and similarities, contributing to our understanding of the evolutionary history of Epipompilus, and consequently of Pompilidae.

8.
J. Hymenopt. Res. ; 66: p. 15-21, 2018.
Artigo em Inglês | Sec. Est. Saúde SP, SESSP-IBPROD, Sec. Est. Saúde SP | ID: but-ib15657

RESUMO

Epipompilus Kohl comprises 52 species of wasps that are parasitoids of spiders; 16 species occur in the Neotropical region and 36 species occur in the Australian region. The biological knowledge of this genus is limited and its interactions and host spiders are still incipient. Here, we report some behavioural and biological characteristics of E. excelsus, a parasitoid of the tube-dwelling spider Ariadna mollis. We observed an E. excelsus female attacking an adult female of A. mollis in São Paulo, Brazil. We photographed daily the larval development of the wasp, from the egg stage to adult emergence. The entire developmental cycle of the wasp took 24 days. This period was shorter than the developmental periods of wasps belonging to other genera of Pompilidae. Although all species within Pompilidae use spiders as host, they present great behavioural diversity, characterized by different ethological sequences. In conclusion, this study demonstrated that the Neotropical species of Epipompilus exhibit biological characteristics similar to the Australian species, acting as a koinobiont ectoparasitoid, but displays differences in larval morphology. Studies on other species could elucidate the extent of these differences and similarities, contributing to our understanding of the evolutionary history of Epipompilus, and consequently of Pompilidae.

9.
Sci Rep ; 7(1): 9188, 2017 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-28835630

RESUMO

One fundamental question in prey luring systems is to understand how visual signals are interpreted by the receiver. Predators lure prey by falsely imitating the signal of a model, or may exploit sensory preferences of the receivers, which search for rewarding signals. Crab spiders reflect ultraviolet (UV) light, ambush pollinators on flowers, and manipulate flower UV signals altering the behavior and response of prey. Whereas crab spiders typically depend on flowers to forage, adult Epicadus heterogaster departs from this standard behavior by preying on pollinators upon green leaves, even in the absence of flowers nearby. This species has a conspicuous abdomen resembling the shape of a flower, which may reflect UV signals similar to that of flowers, and thus attract pollinators. Nevertheless, no empirical evidence is available that E. heterogaster foraging on leaves mimics flowers, nor how this crab spider interacts with its prey. Field and laboratory experiments demonstrated that UV reflection of adult E. heterogaster is the main signal responsible for the attraction of pollinators. This is the first study to demonstrate that a crab spider attracts pollinators regardless of flower UV signal, which may represent an evolutionary pathway beyond the dependence of flowers.


Assuntos
Meio Ambiente , Comportamento Predatório , Aranhas , Fatores Etários , Animais , Comportamento Animal , Cor , Modelos Teóricos , Polinização
10.
Arq. Inst. Biol ; 82: 1-4, 2015. tab
Artigo em Português | LILACS, VETINDEX | ID: biblio-1026348

RESUMO

Este estudo teve como objetivo realizar um levantamento das famílias de himenópteros parasitoides em área de mata atlântica da Reserva Municipal Serra do Japi (23°13' 52,24"S, 46°56'09,00" O), Jundiaí, São Paulo, Brasil. Foram coletados 1.300 himenópteros parasitoides de oito superfamílias e de 23 famílias. A coleta foi realizada durante cinco dias utilizando-se armadilha Malaise, armadilha Moericke e varredura na vegetação. As famílias de maior abundância relativa foram: Diapriidae (45,92%), Braconidae (15,00%), Ichneumonidae (12,92%) e Platygastridae (6,15%). Quatorze famílias tiveram abundância relativa inferior a 1%. Foram registrados na área estudada espécimes de Perilampidae (0,62%) e de Pelecinidae (0,15%). Este estudo é o segundo levantamento da fauna de himenópteros parasitoides na Serra do Japi.(AU)


This study aimed at surveying the families of parasitic Hymenoptera in the area of the Atlantic Forest in Reserva Municipal Serra do Japi (23°13' 52,24"S, 46°56'09,00" W), Jundiai, São Paulo, Brazil. There, 1,300 hymenoptera parasitoids of eight superfamilies and 23 families were collected. The collection was performed for five days using Malaise trap, Moericke trap and "Sweeping" in the Vegetation. Families with the highest relative abundance were: Diapriidae (45.92%), Braconidae (15,00%), Ichneumonidae (12,92%) and Platygastridae (6,15%). Fourteen families showed relative abundance below 1%. Te study area registered specimens of Perilampidae (0,62%) and Pelecinidae (0,15%). Tis work represents the second survey of the hymenoptera parasitoid fauna in Serra do Japi.(AU)


Assuntos
Vespas , Biodiversidade , Himenópteros , Brasil , Insetos
11.
Zoolog Sci ; 31(12): 820-30, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25483794

RESUMO

Ladybird beetles in the tribe Epilachnini include notorious crop pests and model species studied intensively in various fields of evolutionary biology. From a combined dataset of mitochondrial (ND2) and nuclear (28S) DNA sequences, we reconstructed the phylogeny of 46 species of Epilachnini from Asia, Africa, America, and the Australian region: 16 species in Epilachna, 24 species in Henosepilachna, and one species each in Adira, Afidenta, Afidentula, Afissula, Chnootriba, and Epiverta. In our phylogenetic trees, both Epilachna and Henosepilachna were reciprocally polyphyletic. Asian Epilachna species were monophyletic, except for the inclusion of Afissula sp. Asian and Australian Henosepilachna species likewise formed a monophyletic group, excluding H. boisduvali. African Epilachna and Henosepilachna species did not group with their respective Asian and American congeners, but were paraphyletic to other clades (Epilachna species) or formed a separate monophyletic group (Henosepilachna species) together with Chnootriba similis. The American Epilachna species were monophyletic and formed a clade with American Adira clarkii and Asian Afidentula manderstjernae bielawskii; this clade was the sister group to Asian and Australian Henosepilachna, but was distant from Asian Epilachna. Chnootriba was embedded in the African Henosepilachna clade, and Afissula in the Asian Epilachna clade. Epiverta, which is morphologically unique, was the sister group to Asian Epilachna, although with weak support. From reconstructions of biogeographical distribution and host-plant utilization at ancestral nodes, we inferred an African origin for the common ancestor of the species studied, and found the frequency of host shifts to differ greatly between the two major lineages of Epilachnini examined.


Assuntos
Distribuição Animal , Besouros/genética , Besouros/fisiologia , Filogenia , Plantas/classificação , Animais , Filogeografia , Especificidade da Espécie
12.
J Med Entomol ; 51(3): 547-59, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24897847

RESUMO

The medically important spiders Loxosceles intermedia Mello-Leitão and Loxosceles laeta (Nicolet) are segregated in Curitiba, southern Brazil, where L. intermedia is more abundant and widespread than L. laeta. Because they share similar microhabitat preferences and wander in search of web sites, agonistic encounters are likely to occur. The purposes of this study were to describe agonistic interactions and interpret their consequences for the relative abundances and spatial segregation of L. intermedia and L. laeta. Experimental contests were performed between residents and intruders. Asymmetries between contestants included sex, age, species, weight, and residence status. Nine behavioral categories were defined. Through discriminant analyses, it was possible to differentiate spider sex, species, and residence based on their agonistic behaviors. Intruders, juveniles, and L. intermedia individuals were better characterized by exploratory behaviors, whereas L. laeta females were differentiated by aggressiveness. By performing a multiple logistic regression, with winning or defeat as a dependent variable of sex, age, species, size, weight, and residence, it was possible to say that residents and L. intermedia individuals had the highest winning odds in contests, whereas juveniles had lower winning odds than adults. Advantages of the prior residence may help to explain the predominance of L. laeta in old colonization sites, whereas the higher winning odds of L. intermedia and less aggressive behavior toward conspecifics may lead to a successful establishment of dense populations in new sites. A better understanding of agonistic interactions as a mechanism of spacing, segregation, and species replacement among spiders may be helpful for control purposes.


Assuntos
Distribuição Animal , Aranhas/fisiologia , Agressão , Animais , Brasil , Ecossistema , Feminino , Estágios do Ciclo de Vida , Masculino , Densidade Demográfica , Caracteres Sexuais , Aranhas/anatomia & histologia , Aranhas/classificação , Aranhas/crescimento & desenvolvimento
13.
Ann Bot ; 111(1): 143-50, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23131297

RESUMO

BACKGROUND AND AIMS: The protocarnivorous plant Paepalanthus bromelioides (Eriocaulaceae) is similar to bromeliads in that this plant has a rosette-like structure that allows rainwater to accumulate in leaf axils (i.e. phytotelmata). Although the rosettes of P. bromelioides are commonly inhabited by predators (e.g. spiders), their roots are wrapped by a cylindrical termite mound that grows beneath the rosette. In this study it is predicted that these plants can derive nutrients from recycling processes carried out by termites and from predation events that take place inside the rosette. It is also predicted that bacteria living in phytotelmata can accelerate nutrient cycling derived from predators. METHODS: The predictions were tested by surveying plants and animals, and also by performing field experiments in rocky fields from Serra do Cipó, Brazil, using natural abundance and enriched isotopes of (15)N. Laboratory bioassays were also conducted to test proteolytic activities of bacteria from P. bromelioides rosettes. KEY RESULTS: Analyses of (15)N in natural nitrogen abundances showed that the isotopic signature of P. bromelioides is similar to that of carnivorous plants and higher than that of non-carnivorous plants in the study area. Linear mixing models showed that predatory activities on the rosettes (i.e. spider faeces and prey carcass) resulted in overall nitrogen contributions of 26·5 % (a top-down flux). Although nitrogen flux was not detected from termites to plants via decomposition of labelled cardboard, the data on (15)N in natural nitrogen abundance indicated that 67 % of nitrogen from P. bromelioides is derived from termites (a bottom-up flux). Bacteria did not affect nutrient cycling or nitrogen uptake from prey carcasses and spider faeces. CONCLUSIONS: The results suggest that P. bromelioides derive nitrogen from associated predators and termites, despite differences in nitrogen cycling velocities, which seem to have been higher in nitrogen derived from predators (leaves) than from termites (roots). This is the first study that demonstrates partitioning effects from multiple partners in a digestion-based mutualism. Despite most of the nitrogen being absorbed through their roots (via termites), P. bromelioides has all the attributes necessary to be considered as a carnivorous plant in the context of digestive mutualism.


Assuntos
Carnivoridade , Eriocaulaceae/fisiologia , Isópteros/fisiologia , Comportamento Predatório/fisiologia , Aranhas/fisiologia , Simbiose/fisiologia , Animais , Brasil , Nitrogênio/metabolismo , Isótopos de Nitrogênio , Folhas de Planta/microbiologia , Folhas de Planta/fisiologia , Tenebrio/fisiologia
14.
PLoS One ; 7(4): e34592, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22545086

RESUMO

Species that differ in their social system, and thus in traits such as group size and dispersal timing, may differ in their use of resources along spatial, temporal, or dietary dimensions. The role of sociality in creating differences in habitat use is best explored by studying closely related species or socially polymorphic species that differ in their social system, but share a common environment. Here we investigate whether five sympatric Anelosimus spider species that range from nearly solitary to highly social differ in their use of space and in their phenology as a function of their social system. By studying these species in Serra do Japi, Brazil, we find that the more social species, which form larger, longer-lived colonies, tend to live inside the forest, where sturdier, longer lasting vegetation is likely to offer better support for their nests. The less social species, which form single-family groups, in contrast, tend to occur on the forest edge where the vegetation is less robust. Within these two microhabitats, species with longer-lived colonies tend to occupy the potentially more stable positions closer to the core of the plants, while those with smaller and shorter-lived colonies build their nests towards the branch tips. The species further separate in their use of common habitat due to differences in the timing of their reproductive season. These patterns of habitat use suggest that the degree of sociality can enable otherwise similar species to differ from one another in ways that may facilitate their co-occurrence in a shared environment, a possibility that deserves further consideration.


Assuntos
Aranhas/classificação , Aranhas/fisiologia , Animais , Comportamento Animal , Brasil , Ecossistema , Filogenia , Comportamento Social , Aranhas/genética
15.
Environ Entomol ; 39(6): 1724-30, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22182535

RESUMO

Phloea subquadrata Spinola, 1837 (Pentatomoidea: Phloeidae) belongs to a small family of sap feeding bugs that live on tree trunks, on which they are cryptic because of their coloration and flat body. There are a few studies concerning phloeid anatomy and biology, but almost nothing is known about their ecology. In this study, population dynamics and structure of P. subquadrata on the host tree Plinia cauliflora (Myrtaceae) were investigated during 3 yr in a semideciduous forest in southeast Brazil. Nymphs and adults were active all year round, but the egg-laying season was mainly restricted to the warm, rainy season (September-March). Population density slightly increased at the end of this season because of reproduction. Population age structure changed markedly over time, with nymphs reaching the adult stage in the subsequent early-to-mid rainy season. Abiotic factors, such as rainfall and temperature, were correlated with female oviposition and population dynamics and phenology. Sex ratio was male-biased, not differing from 1:1 only during the adult recruitment period (October-January). Under dry weather conditions, phloeids were distributed closer to the base of the tree trunks when compared with rainy conditions. Our results suggest that seasonality and variations in weather conditions are important driving forces of population dynamics and phenology of P. subquadrata, as well as the microhabitat selection on host trees.


Assuntos
Hemípteros/fisiologia , Interações Hospedeiro-Parasita , Myrtaceae/parasitologia , Animais , Feminino , Masculino , Densidade Demográfica , Dinâmica Populacional , Chuva , Reprodução , Estações do Ano , Razão de Masculinidade , Temperatura
16.
Ecology ; 89(11): 3105-3115, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31766796

RESUMO

Although specific associations between spiders and particular types of plants have been reported for several taxonomic groups, their consequences for spiders and plants are still poorly understood. The most common South American lynx spiders, Peucetia flava and P. rubrolineata, live strictly associated with various plant species that have glandular trichomes. To understand more about these spider-plant relationships, we investigated the influence of the spiders on the fitness of a neotropical glandular shrub (Trichogoniopsis adenantha) and on the arthropod community structure on the plant. We also tested whether glandular hairs provided any benefit to the spiders. Spiders reduced the abundance of several species and guilds of herbivores on the leaves and inflorescences. Consequently, damage to the leaves, capitula, ovaries, corollas, and stigmas caused by leaf-mining and chewing insects, as well as endophagous insects, were strongly reduced in the presence of Peucetia spp. Although the spiders fed on flower visitors, their negative influence on ovary fertilization was only marginally nonsignificant (P = 0.065). Spiders on plants of Trichogoniopsis adenantha that fed on common fruit flies that had died before adhering to the glandular trichomes did not lose body mass. However, those living on plants without stalked glandular trichomes (Melissa officinalis) did not feed on dead flies and lost 13-20% of their biomass. These results indicate that Peucetia spiders are effective plant bodyguards and that when there is limited live prey they may feed on insect carcasses adhered to glandular trichomes. Since several spider species of the genus Peucetia live strictly associated with glandular trichome-bearing plants in neotropical, Neartic, Paleartic, and Afrotropical regions, this type of facultative mutualism involving Peucetia and glandular plants may be common worldwide.

17.
Interciencia ; Interciencia;31(11): 807-816, nov. 2006. tab
Artigo em Português | LILACS | ID: lil-449353

RESUMO

En general, los procesos de polinización y dispersión de semillas son fundamentales para entender la colonización y la regeneración de ecosistemas. En este trabajo se analizó la composición florística y sus síndromes de polinización y dispersión de semillas de la familia Solanaceae en bosques mesófilos de regiones equivalentes de México y Brasil. Se partió de la premisa que bosques fisonómicamente semejantes distribuidos en regiones equivalentes deberían tener procesos funcionales equiparables. Los resultados confirman las diferencias en composición florística pero ambos bosques comparten un número similar de especies de Solaneacea (México 25 y Brasil 26). Para el caso de México se encontró que la distribución y abundancia de Solanaceae está primeramente asociado a las condiciones de perturbación y de humedad, mientras que para el caso de Brasil la distribución y abundancia está preferentemente relacionada a la elevación y la humedad. En ambas regiones se encontró que el síndrome de polinización dominante es la melitofília; sin embargo, al comparar los síndromes de dispersión de semillas se verificó que hay diferencias significativas. Para México prevalece la ornitocoria mientras que para Brasil la quiropterocoria. Esto coincide con los centros de diversificación de aves en Centro América y de quirópteros en Sudamérica, lo que sugiere que las especies de solanáceas han experimentado un proceso de coadapación funcional con respecto a los grupos dispersores de semillas de aves y murciélagos en cada región


Assuntos
Ecossistema , Solanaceae , Árvores , Brasil , Ecologia , México
18.
Ecology ; 87(4): 803-8, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16676522

RESUMO

Although bromeliads are believed to obtain nutrients from debris deposited by animals in their rosettes, there is little evidence to support this assumption. Using stable isotope methods, we found that the Neotropical jumping spider Psecas chapoda (Salticidae), which lives strictly associated with the terrestrial bromeliad Bromelia balansae, contributed 18% of the total nitrogen of its host plant in a greenhouse experiment. In a one-year field experiment, plants with spiders produced leaves 15% longer than plants from which the spiders were excluded. This is the first study to show nutrient provisioning in a spider-plant system. Because several animal species live strictly associated with bromeliad rosettes, this type of facultative mutualism involving the Bromeliaceae may be more common than previously thought.


Assuntos
Desenvolvimento Vegetal , Aranhas/fisiologia , Análise de Variância , Animais , Cromatografia Líquida de Alta Pressão , Nitrogênio/metabolismo
19.
J Med Entomol ; 42(5): 756-65, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16363158

RESUMO

A survey was done of the environments and substrata occupied by Loxosceles intermedia Mello-Leitão, 1934 and Loxosceles laeta (Nicolet, 1849) (Araneae: Sicariidae) in urban woods and anthropic constructions in Curitiba. In total, 2,099 trees, 364 decaying logs as well as stones and roots, built-up areas, and wasteland in six urban parks and 60 residences were inspected. In total, 1,775 m2 of vegetation was inspected, but spiders and their vestiges were collected only in and around buildings in urban parks and residences. L. intermedia was more common than L. laeta and occurred both indoors and outdoors, whereas L. laeta was more common indoors in wooden houses. The two species did not occur in the same microhabitats, although both preferred paper, wood, and construction materials. Spiders collected in urban parks were heavier than those collected in residences, although only males collected in urban parks were larger than those from residences. The lack of vestiges indicative of a previous occupation in the urban parks suggested that both species occupied primarily the anthropic environment where they found numerous substrata that offered thermal isolation and suitable conditions for web fixation, ecdysis, and reproduction.


Assuntos
Demografia , Meio Ambiente , Aranhas/fisiologia , Animais , Pesos e Medidas Corporais , Brasil , Cidades , Feminino , Masculino , Densidade Demográfica , Fatores Sexuais , Especificidade da Espécie , Aranhas/anatomia & histologia , Estatísticas não Paramétricas
20.
Neotrop. entomol ; 34(1): 7-14, Jan.-Feb. 2005. ilus, graf, tab
Artigo em Inglês | LILACS | ID: lil-451490

RESUMO

Oncideres humeralis Thomson (Cerambycidae) was observed girdling the main trunk of plants of the Melastomataceae family in south-eastern Brazil. The main objectives of this work were to identify which host plants O. humeralis selects in the field and which are the characteristics of the preferred plants. O. humeralis specifically used Melastomataceae as host plants, attacking only four of the 11 species present in the study area. From the four attacked species, Miconia sellowiana Naudin and M. jucunda Triana were the preferred owes; they are the most abundant and the largest species, respectively. When the plants were taller, O. humeralis girdled the trunk at higher positions, indicating that females select plants with optimum trunk diameter and adjust the point to girdle according to the host height. Females also selected plants with greater numbers of secondary branches. These results indicate that O. humeralis is specific to certain species of Melastomataceae, and that host plants are selected on the basis of their abundance, size or number of secondary branches.


Oncideres humeralis Thomson (Cerambycidae) foi observado serrando o tronco principal de plantas da família Melastomataceae no sudeste do Brasil. Os principais objetivos deste trabalho identificar quais plantas hospedeiras O. humeralis seleciona no campo e quais as características das plantas preferidas. O. humeralis usou somente Melastomataceae como plantas hospedeiras, atacando quatro das 11 espécies presentes na área de estudo. Das quatro espécies atacadas, Miconia sellowiana Naudin e M. jucunda Triana, a espécie mais abundante e a maior, respectivamente, foram as preferidas. Quando as plantas eram altas, O. humeralis serrou o tronco em posições mais elevadas, indicando que as fêmeas selecionam plantas com diâmetro ótimo de tronco e ajustam o ponto para serrar em função da altura da hospedeira. As fêmeas também selecionaram plantas com maior número de ramos secundários. Estes resultados indicam que O. humeralis apresenta especificidade para determinadas espécies de Melastomataceae e que plantas hospedeiras são selecionadas pela sua abundância, tamanho ou número de ramos secundários.


Assuntos
Besouros/metabolismo , Besouros/parasitologia , Melastomataceae/microbiologia
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