Tritrophic interactions in a pollination system: impacts of species composition and size of flower patches on the hunting success of a flower-dwelling spider

Schmalhofer, Victoria R.

doi:10.1007/s004420100726

Cited by 48 publications

(45 citation statements)

References 53 publications

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“…These values were calculated by looking at losses from the steps ''insect within range'' to ''attacked''. Our findings explain why previous authors claimed that crab spiders are apparently inefficient hunters (Morse 1979, Schmalhofer 2001, Dukas and Morse 2003, Robertson and Kelmash Maguire 2005, Reader et al 2006, Brechbü hl et al 2010a). Morse (1979) also found the crab spider M. calycina refusing to attack in 37.2% of the cases.…”

Section: Discussionsupporting

confidence: 75%

Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

Brechbühl¹,

Casas

Bacher³

2011

Ecosphere

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Citation: Brechbü hl, R., J. Casas, and S. Bacher. 2011. Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence. Ecosphere 2(12):133. doi:10.1890/ES11-00323.1Abstract. Optimal diet theory (ODT) postulates that predators adjust their foraging decisions by calculating a prey value from the potential biomass gain, handling time, prey vulnerability and encounter rate. Tests of ODT have however so far mainly been restricted to laboratory settings. By video surveillance, we gathered a large data set of more than 2000 field observations of crab spider (Misumena vatia) encounters with potential prey. We then tested whether the complex ODT or two simpler models (prey identity and prey traits) best explain foraging decisions. Insect prey were killed with an average chance of 3.5% when alighting on an inflorescence harboring a spider. Spiders refused to attack suitable prey in 46-79% of encounters when prey was in attack range, indicating an over-abundance of prey relative to the needs of the spiders. Reduction of opportunities to capture prey along the prey capture sequence differed among pollinator groups, with syrphids and solitary bees showing strong avoidance of spiders early in the sequence and bumblebees resisting the final strike. Simple prey traits explained foraging decisions better than ODT, which was not supported. In the absence of food limitation, optimality decisions may be less stringent. The over-abundance of prey indicates that, in contrast to current theory, prey encounter rates are not the most important factor driving predator foraging decisions. Our results are highly coherent with those obtained in earlier field studies on patch leaving strategies and predator-prey encounters. Prey overabundance and non-optimal predator behavior are apparently not uncommon in nature, and we highlight some of the implications for predator-prey theory.

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Section: Discussionsupporting

confidence: 75%

Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

Brechbühl¹,

Casas

Bacher³

2011

Ecosphere

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“…Moreover, the lack of relationship between leaf size and diversity of predators in our study may be related to the habitat scale used, i.e., dry leaves, which represent a small space to be colonized by these organisms. The competition between predators, especially spiders, for shelter against desiccation (Riechert and Tracy, 1975) or predators (Rosenberg, 1990), and foraging sites (Schmalhofer 2001;Romero and Vasconcellos-Neto, 2003) may also act at the scale investigated in our study, preventing the increase in species diversity in this guild.…”

Section: Response Variablementioning

confidence: 89%

Vertical stratification and effect of petiole and dry leaf size on arthropod feeding guilds in Cecropia pachystachya(Urticaceae)

et al. 2015

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This study aimed to test for vertical stratification and the effects of dry leaf size on herbivore and predator arthropods and petiole length on insect borers in Cecropia pachystachya. The leaves were sampled in three strata: attached to the plant, suspended on the vegetation and on the ground. We detected vertical stratification only in the guild of predator arthropods associated with dry leaves, with lower richness and abundance in the attached stratum. In addition, larger leaves positively affected the insect herbivore fauna, whereas the richness and abundance of insect borers increased with petiole length. The greater isolation of leaves attached to trees relative to the surrounding vegetation likely creates greater difficulty for dispersal and colonization by non-winged predators such as spiders. Larger dry leaves provide more shelter against predators and climate variations for insect herbivores. Moreover, larger petioles increase the availability of resources and nesting sites for insect borers. These results are consistent with other studies that found a similarity in the structure of feeding guilds across vertical strata and with studies that showed an increase in species richness and abundance of free-feeding insect herbivores with increasing structural complexity of their host.Keywords: insect herbivores, bark beetles, predators, habitat complexity, resource availability.Estratificação vertical e efeito do tamanho de pecíolos e folhas secas de Cecropia pachystachya sobre guildas alimentares de artrópodes (Urticaceae) ResumoOs objetivos do presente trabalho foram testar as hipóteses de que existe estratificação vertical e efeito do tamanho de folhas secas de Cecropia pachystachya sobre artrópodes herbívoros e predadores, e efeito do tamanho dos pecíolos sobre insetos brocadores. As folhas foram amostradas em três estratos: presas à planta, caídas sobre a vegetação e no solo. Foi verificada estratificação vertical apenas para os artrópodes predadores, com menor riqueza e abundância no estrato presa. Além disso, folhas maiores afetam positivamente a fauna de insetos herbívoros, enquanto que a riqueza e abundância de brocadores aumentam com o tamanho do pecíolo. O maior isolamento das folhas presas em relação à vegetação do entorno provavelmente determina maior dificuldade de dispersão e colonização por predadores não alados, como aranhas. Folhas secas maiores oferecem maiores áreas de refúgio e abrigo contra predadores e variações climáticas para insetos herbívoros. Além disso, maiores pecíolos aumentam a disponibilidade de alimento e locais para nidificação dos insetos brocadores. Estes resultados são consistentes com estudos que encontraram uma similaridade na estrutura de guildas alimentares entre estratos verticais. Corroboram também estudos que mostram o aumento da riqueza e abundância de insetos herbívoros de vida livre com o aumento da complexidade estrutural do hospedeiro.Palavras-chave: insetos herbívoros, brocadores, predadores, complexidade do habitat, disponibilidade de recurso.

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“…Plantas abrigam diferentes composição de guildas de aranhas e estas diferenças podem ser em decorrência às variáve is relacionadas com a arquitetura destes hábitats (Hatley & MacMahon 1980, Robinson 1981, Scheidler 1990, Gunnarsson 1990, Evans 1997, Halaj et al 1997. Componentes estrutura is da vegetação afetam profundamente sua densidade e diversidade (Robinson 1981, Gunnarsson 1990, 1996, visto que as plantas são importantes como sítios para construção de teias (Greenstone 1984, Figueira & Vasconcellos-Neto 1991, Herberstein, 1997, para abrigo contra dessecação (Riechert & Tracy 1975) ou inimigos naturais (Gunnarsson 1990(Gunnarsson , 1996, para forrageamento (Morse & Fritz 1982, Morse 1990, Schmalhofer 2001, Romero & Vasconcellos-Neto 2003, reprodução e oviposição (Rossa-Feres et al 2000, Smith 2000, Romero & Vasconcellos-Neto 2003, Romero & Vasconcellos-Neto 2005.…”

Section: Introductionunclassified

Efeitos da estrutura da vegetação na composição da assembleia de aranhas (Arachnida: Araneae) em estrato arbóreo de diferentes fitofisionomias do Cerrado

Moraes¹

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Perceive and understand the factors that determine and regulate the diversity of species is one of the central questions in ecology. Standards and processes are poorly documented for the bottom-up effect, for which we can mention two main hypotheses about the factors that would be regulating species diversity: (1) hypothesis of taxonomic diversity and (2) hypothesis of structural heterogeneity. The hypothesis of structural heterogeneity has been gaining attention in many studies with different taxonomic groups and environments, such as the invertebrate response to vegetation structure, and between groups of organisms more susceptible to the effects of habitat architecture are arthropods. The vegetation is an element that provides the habitat structural complexity, because can represent a whole plant habitat, and small variatio ns in its architecture can have consequences in the community structure and foraging efficie nc y, for example, Spiders. Plants harboring different composition of spider guilds and these differences may be due to the variables related to the architecture of these habitats, because the hunting strategies adopted by different guilds of spiders has a strong relationship with the vegetation structure. Since the importance of vegetation structure in the composition of the assembly of spiders, especially as the hunting strategies adopted by these, this study evaluated the relationship between aspects of the structure of arboreal branches, leaf density branch, leaf area, nodal distance with composition of the board of spiders, taking into account their classification into guilds. There was also a comparison of these architectural measures between points collected in the cerrado sensu stricto and gallery forest, as well as comparing the results of correlations between variables architecture and composition of meetings for each of the two forest types. The objective was to understand the relationship of tree branches architecture with the assembly of spiders. The study was conducted at Fazenda Água Limpa and the Parque Estadual da Serra de Caldas Novas. The vegetation types sampled outside the gallery forest and the cerrado sensu stricto and the collection technique was the umbrella-entomological with a square meter. In total, we sampled 182 points in 84 gallery forest and 98 in cerrado sensu stricto. Spiders were collected in 1512 in total, of which the most abundant families were Anyphaenidae, Salticidae and Theridiidae, the first two belonging to the guild runners hunting spiders (CO) and the third the guild of builders irregular webs (IT). Of this total, 10.52% were adults and individuals were identified in kind, Thwaitesia affinis being the most abundant species. No species was common to two forest types. The results of the Analyzes Redundancy showed correlations between the web construction of guilds and the distance between the nodes of the leaves, suggesting that cobwebs need more space for building them, and correlation between hunting spiders runners and the density index leaf, in...

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Tritrophic interactions in a pollination system: impacts of species composition and size of flower patches on the hunting success of a flower-dwelling spider

Cited by 48 publications

References 53 publications

Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

Vertical stratification and effect of petiole and dry leaf size on arthropod feeding guilds in Cecropia pachystachya(Urticaceae)

Efeitos da estrutura da vegetação na composição da assembleia de aranhas (Arachnida: Araneae) em estrato arbóreo de diferentes fitofisionomias do Cerrado

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