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Conservative biological control promotes the use of native natural enemies to limit the size and growth of pest populations. Although spiders constitute one of the most important groups of native predators in several crops, their trophic ecology remains largely unknown, especially for several generalist taxa. In laboratory, we assessed the predatory behaviour of a wandering spider (the wolf spider Lycosa thorelli (Keyserling, 1877) against several arthropods varying in size and trophic positions, all found in South American soybean and rice crops. As prey we used the bug Piezodorus guildinii (Westwood, 1837) as well as larvae and adults of the moth Spodoptera frugiperda (Smith, 1797), both being considered important pests in Uruguayan crops. We also used several non‐pest arthropods as prey, sarcophagid flies, carabid beetles and wolf spiders. All prey were attacked in more or less high, although not statistically differing, proportions. However, carabids were not consumed, and bugs were consumed in significantly lower proportions than flies. A negative correlation was found between prey size and acceptance rate. Immobilization times were longer against larvae when compared to moths and flies, while predatory sequences were longer for bugs when compared to flies, moths and spiders. In addition, we found a positive effect of prey size on predatory sequence length and complexity. Our results confirm the ability of spiders to attack and feed upon prey with different morphologies, included well‐defended arthropods, and their potential use as natural enemies of several pests in South American crops. [ABSTRACT FROM AUTHOR]

Dispersal is a key process in metapopulation dynamics and metacommunity assembly as it may be affected by a variety of factors acting at different spatial scales. While dispersal is known to evolve in response to landscape-related selection pressures, local dynamics are merely driven by conditional responses, for instance by habitat quality and density. Local and regional factors are thus expected to impact dispersal, either synergistically or antagonistically. Moreover, such responses do not need to coincide among all life stages because different life stages are expected to incur different costs, either intrinsically due to for instance differences in size or extrinsically because of demographic changes. Our general objective is consequently to test for the likely opposite effects of main factors acting on dispersal, i.e. local density and habitat configuration, at different life-stages in a salt marsh inhabiting spider Pardosa purbeckensis (F.O.P.-Cambridge 1895). Using a combination of both field and laboratory experiments on pre-dispersal behaviour, we demonstrate a significant negative density-dependence for natal dispersal, but no alike effect at the adult stage. No effects of the local habitat structure were detected. Therefore, good mother body condition could be interpreted by juveniles during the phase of maternal care as suitable living conditions, decreasing emigration rate. Although dispersal is known to have a genetic basis, local factors eventually overrule this source of variation. [ABSTRACT FROM AUTHOR]

In this paper, we compare the spider faunas of two close geographical entities: Brittany (western France, 634 species) and Great Britain (UK, 639 species). There was a high percentage of shared species (67%, 513 species) and differences among families and genera were attributed to biogeography and geological history (i.e. glaciation), much less by rarity and possible under-recording. Some northern species are absent from Brittany and many southern species from Great Britain. Further surveys, mainly targeting winter maturing species, are needed. [ABSTRACT FROM AUTHOR]

During range expansion, the most dispersive individuals make up the range front, and assortative mating between these dispersive phenotypes leads to increased dispersiveness (i.e. spatial sorting). The precise inheritance of dispersal, however, is to date largely unknown in many organisms, thereby hampering any progress in evaluating the adaptive potential of species during range expansion. Using the spider mite Tetranychus urticae, we therefore empirically simulated spatial sorting by means of artificial selection on a unique pre-dispersal behaviour, tightly related to emigration. To separate directionality of the response from potential drift, we mimicked a recurrent low number of founders in replicated selection regimes. Afterwards, we inferred the mode of inheritance of the pre-dispersal behaviour by performing reciprocal crosses between selected (i.e. dispersive) and non-selected (i.e. non-dispersive) mites and by screening for endosymbionts known to be associated with changes in dispersal behaviour. Despite the recurrent low number of founders, the aerial dispersal behaviour responded strongly to the imposed selection pressure. The behaviour furthermore showed a maternal inheritance, though independent of any known dispersal-related endosymbionts. Though cytoplasmic inheritance cannot fully be excluded, we attribute the observed strong and rapid, maternally influenced response in dispersal to transgenerational epigenetic effects. Consequently, we can expect fast evolutionary dynamics during range expansion in the species. [ABSTRACT FROM AUTHOR]

Remotely sensed data are frequently employed for monitoring vegetation and for estimating herbivore diversity. Their use for predicting predator arthropod species abundance and richness has also been investigated with success for ants and beetles in forests using normalised difference vegetation index ( NDVI) and for beetles in mountain forests using light detection and ranging data., We investigated whether vegetation indices, derived from multispectral SPOT imagery could predict abundance and species richness of ground active spiders and ground beetles in a new ecological context, the floodplain meadows of the Loire River in Western Europe. Using pitfall traps, we collected carabids and spiders in the field., Maximum vegetation height, litter-depth and plant species richness best explained species assemblages of both groups (multivariate analyses). NDVI and enhanced vegetation index ( EVI 2) were strongly related to activity-density and species richness for ground beetles only, EVI 2 being the best surrogate. Relationships between vegetation indices and spider assemblage patterns were either non-significant or weak., We demonstrated that EVI 2 is a good surrogate of the abundance and richness of carabid species in a temperate floodplain, and has potential as a low cost method for mapping arthropod assemblages at large spatial scales., Our approach provides a tool which contributes to biodiversity assessment at large spatial scales. It can also contribute to the prioritisation of conservation areas and early change detection, as carabids are keystone indicators. [ABSTRACT FROM AUTHOR]

As a result of an invasion by the native grass Elymus athericus (Link) Kerguélen (Poaceae) in the last 10 years, a major change in vegetation cover has occurred in salt marshes of the Mont Saint-Michel bay, Western France. The impact of such an invasion on carabid assemblages, a dominant group of terrestrial arthropods in these habitats and containing several stenotopic species, is investigated here. In our study site, carabid data are available from 1983 and 1984, allowing a comparison of species distribution ranges in salt marshes before (1983-1984) and after (2002) the E. athericus invasion. A total of 16,867 adults belonging to 40 species were caught. By considering the presence-absence of species shared between studies, we show that the invasion by E. athericus promoted the progression of non-coastal species (mainly Pterostichus s.l. spp.). This did however not interfere with resident species distributions, finally resulting in higher carabid species richness in the entire area. The species composition and abundances of carabid assemblages were also compared between natural and invaded stations in 2002. The main result is that abundances of some halophilic species decreased in one invaded plot (in case of Pogonus chalceus (Marsham 1802)) whereas the opposite pattern was observed for other species (e.g., Bembidion minimum (Fabricius 1792)). Invaded habitats were characterized by lower percentages of halophilic species and higher total species richness. [ABSTRACT FROM AUTHOR]

Salt-marsh invasions by the grass Elymus athericus (Poaceae) recently transformed usual areas dominated by Atriplex portulacoides (Chenopodiaceae) into homogeneous meadows. Two wolf spider species, Pardosa purbeckensis and Arctosa fulvolineata, show contrasting densities and habitat preferences in salt marshes (respectively dominant and co-dominant ground-living spiders) and oppositely respond to the grass invasion. This allowed us to test whether invasive species that alter habitat structure affect reproduction in addition to previously recorded changes in density. Reproductive traits (female mass, cocoon mass, number and volume of eggs, hatched cocoon as a proxy of reproduction date) were studied in both invaded and natural salt marshes during 2007 and 2008 in the Mont St-Michel Bay (France). In both species, reproductive outputs (cocoon mass) were higher in optimal habitats and volume of eggs was found to be independent from female mass, whereas the latter significantly influenced the number of eggs. In A. fulvolineata, lower reproductive outputs due to less numerous although larger eggs were found in suboptimal habitats whereas the opposite pattern was found in optimal habitats, showing the existence of plastic phenotypic trade-offs in habitats of different qualities. In P. purbeckensis, despite differences in population size among habitats, no reproductive trade-off was found. This study thus shows that two sympatric species belonging to the same family can differ in reproductive strategies and phenotypic plasticity under changes in habitat suitability. [ABSTRACT FROM AUTHOR]

Fishing spiders (Dolomedes spp.) make an interesting model to predict the impact of global changes because they are generalist, opportunistic predators, whose distribution is driven mostly by abiotic factors. Yet, the two European species are expected to react differently to forthcoming environmental changes, because of habitat specialization and initial range. We used an original combination of habitat and dispersal data to revisit these predictions under various climatic scenarios. We used the future range of suitable habitat, predicted with habitat variables only, as a base layer to further predict the range or reachable habitat by accounting for both dispersal ability and landscape connectivity. Our results confirm the northward shift in range and indicate that the area of co-occurrences should also increase. However, reachable habitat should expand less than suitable habitat, especially when accounting for landscape connectivity. In addition, the potential range expansion was further limited for the red-listed D. plantarius, which is more of a habitat specialist and has a lower ability to disperse. This study highlights the importance of looking beyond habitat variables to produce more accurate predictions for the future of arthropods populations. [ABSTRACT FROM AUTHOR]

Although species delimitation is often controversial, emerging DNA-based and classical morphology-based methods are rarely compared using large-scale samplings, even less in the case of widely distributed species that have distant, allopatric populations. In the current study, we examined species boundaries within two wolf spider species of the genus Pardosa (Araneae, Lycosidae), P. riparia and P. palustris. Wolf spiders constitute an excellent model for testing the relevance of traditional vs. modern methods in species and population delimitation because several closely related species are distributed over cross-continental geographic ranges. Allopatric populations of the two Pardosa species were sampled across Europe to Far East Russia (latitudinal range > 150°) and several dozen individuals were studied using morphological characters (morphometry of three measures for both sexes, plus five in males only and two in females only), DNA barcoding (COI sequencing) and double-digest restriction site associated DNA sequencing (ddRADseq). The results obtained allow for changing the taxonomic status of two Far East Russian populations to subspecies and ddRADseq proved to be a powerful tool for taxonomic research despite scarce sampling and inherent subjectivity of species delimitation in allopatry. Overall, this study pleads for both multi-criteria and more population-based studies in taxonomy. [ABSTRACT FROM AUTHOR]

• Hedgerows are key multifunctional habitats in agricultural landscapes. • Drivers of hedgerow multifunctionality remain unexplored. • Local variables affect individual ecological functions of hedgerows. • Hedgerow density in the landscape is key to hedgerow multifunctionality. • Ongoing hedgerow loss jeopardizes restoration and replanting efforts. Hedgerows are key wildlife habitats in agricultural landscapes, with presumably high multifunctionality – that is the capacity to provide multiple ecological, agronomic or cultural functions. However, knowledge gaps remain regarding the drivers of hedgerow multifunctionality and potential synergies and trade-offs between functions. In particular, it is unknown in which landscapes hedgerows best support a range of taxa and associated functions. We assessed the effects of hedgerow features, adjoining farming systems, landscape context, and their interactions on hedgerow multifunctionality based on four ecological functions – biodiversity conservation, potential pollination, potential predation, and pest colonization. We estimated these functions by the abundance and diversity of plant and arthropod taxa in 40 hedgerows, in Brittany (France). Results support previous studies showing the beneficial effects of flower cover, margin width, adjacent organic farming, and other variables related to hedgerow structural complexity on individual taxa or proxies of functions. Most importantly, our study reveals that hedgerows are more multifunctional in landscapes with dense hedgerow networks (so-called 'bocage' landscapes), which is likely the result of greater habitat amount, connectivity, and environmental heterogeneity. In addition, we find weak correlations between proxies of functions, and more synergies than trade-offs in response to the explanatory variables, indicating that there is considerable scope for improving the ecological value of hedgerows. We draw attention to the fact that ongoing destruction of hedgerow networks, including wide and structurally complex hedgerows, might lead to long-term or irretrievable loss of associated species and ecological functions, jeopardizing restoration and replanting efforts. [ABSTRACT FROM AUTHOR]