Landscape features drive insectivorous bat activity in Indian rice fields

Context Insectivorous bats have been shown to control a number of agricultural insect pests. As bats exhibit species-specific responses to the surrounding landscape, tied closely to their morphology and foraging mode, the activity and distribution patterns of bats, and consequently the ecosystem services they provide, are influenced by the landscape characteristics. Objectives This study aims to determine which features in the landscape surrounding rice fields influence the activity levels of insectivorous bats, and at what scales they are most influential. Methods We collected acoustic recordings to determine activity levels of seven bat sonotypes in rice fields surrounded by a variety of land-cover types in the Nagaon district of Assam, India. Using this, we determined the most important set of features in the surrounding landscape, and the scales at which had the strongest impact, for each sonotype. Results Our results suggest that tree cover variables are the most important predictors of bat activity in rice fields. Distance to nearest forest, area of forest within 1 km, distance to nearest forest edge, and landscape heterogeneity influenced all five of the analysed bat sonotypes. Also important were the amount of urban land within 1 km, which exerted a negative effect on the activity of one sonotype, and moonlight activity, which negatively influenced the activity levels of one sonotype. Conclusion Our results demonstrate that when flying over rice fields, bat activity is most influenced by presence and proximity of trees. Therefore, increasing tree cover in agricultural landscapes will increase bat activity and likely the level of pest control

Insectivorous bats in Indian rice fields respond to moonlight, temperature, and insect activity

ABSTRACT: Context - Rice, India’s most widely grown crop, suffers substantial and increasing yield loss to insect pests. Insectivorous bats are known suppressors of insect pests, providing significant economic value to agricultural systems worldwide, yet their ecology in Indian agricultural landscapes is poorly understood. Objectives - We assess the influence of key biotic and abiotic factors on the activity of insectivorous bats over the growing season and within a night in a rice cultivation landscape. Methods - Passive acoustic recorders were used to track bat activity in a rice field in the Sonitpur district of Assam, India. We used generalised linear mixed models to analyse the effect of temperature, insect activity, and moonlight intensity on the activity of six bat sonotypes. We also used a multimodal analysis to describe the within-night activity patterns of these sonotypes. Results - Minimum nightly temperature and moonlight intensity had a positive and negative influence, respectively, on the activity of six bat sonotypes, while the activity of four bat sonotypes increased with insect activity. Within-night activity showed one of two patterns: three sonotypes displayed a dusk peak in activity, while the three other sonotypes were active through the night. Conclusion - The potential to maximise natural pest control in agricultural landscapes can only be realised through understanding the ecology of natural enemies in these landscapes. Our findings suggest that bats in rice fields are tracking insects over a season and within a night, pointing to a valuable ecosystem service in Indian agriculture that is yet to be quantified.info:eu-repo/semantics/publishedVersio

La osmoregulación como factor potencial de la distribución diferencial de dos especies crípticas de góbido, Pomatoschistus microps y P. marmoratus, en las lagunas mediterráneas francesas

This study was aimed at the detection of potential differences in the osmoregulatory capacity of two cryptic species of gobies, Pomatoschistus microps (Krøyer, 1838) and P. marmoratus (Risso, 1810), that have different distributions in French Mediterranean lagoons characterised by different salinity regimes. Specimens of both species were experimentally exposed to different salinities, their salinity tolerance was evaluated and their blood osmolality was measured. Both species are strong osmoregulators over a wide range of salinities but P. microps showed higher performances of hyper-regulation at very low salinities (10 and 40 mosm/kg, i.e. freshwater 0.3 and 1.4) and of hypo-regulation at high salinities (1500 mosm/kg, 51). Only P. microps was able to tolerate freshwater exposure over 4 days. We conclude that the high osmoregulatory capacity found in P. microps is linked to its better survival at very low salinities and is a physiological requirement for living in areas such as the Mauguio lagoon where salinity is highly variable. In contrast, as osmoregulation of P. marmoratus is less efficient at extreme salinities, this species cannot colonise such environments and is restricted to habitats where salinity is more stable, such as the Thau lagoon.Este estudio tuvo por objeto la detección de diferencias potenciales en la capacidad osmorreguladora de dos especies crípticas de góbido, Pomatoschistus microps (Krøyer, 1838) y P. marmoratus (Risso, 1810), que presentan diferentes áreas de distribución en lagunas mediterráneas francesas caracterizadas por regímenes de salinidad distintos. Especímenes de ambas especies fueron expuestos experimentalmente a diferentes salinidades, evaluándose su tolerancia a la salinidad y midiéndose su osmolalidad sanguínea. Ambas especies tienen una amplia capacidad osmoreguladora en un amplio rango de salinidades. Sin embargo, en comparación con P. marmoratus, P. microps mostró mayores rendimientos hiper-regulatorios a salinidades muy bajas (10 y 40 mosm/kg, es decir agua dulce 0.3 y 1.4) e hipo-regulatorios a salinidades altas (1500 mosm/kg, 51). Sólo P. microps fue capaz de tolerar la exposición al agua dulce durante 4 días. Podemos concluir que la gran capacidad osmoreguladora encontrada en P. microps está ligada a su mayor supervivencia a salinidades muy bajas, siendo un requerimiento fisiológico para vivir en áreas tales como la laguna de Mauguio, donde la salinidad es muy variable. Por el contrario, puesto que la osmoregulación de P. marmoratus es menos eficiente en salinidades extremas, esta especie no puede colonizar tales ambientes y se ve restringida a hábitats donde la salinidad es más estable, como la laguna de Tha

The drivers of plant turnover change across spatial scales in the Azores

Beta diversity patterns are essential for understanding how biological communities are structured. Geographical and environmental factors, as well as species dispersal ability, are important drivers of beta diversity, but their relative importance may vary across spatial scales. In this study, we evaluate whether beta diversity changes across geographical scales and analyse how different drivers affect turnover patterns of native seed plants in an oceanic archipelago, the Azores (Portugal). Using a 500 × 500 m resolution grid, we selected cells that are covered by one of the following habitats: native forest, naturalized vegetation and seminatural pastures. We calculated species turnover at three spatial scales: 1) between islands, 2) between cells within each island, and finally 3) between cells of each of the habitats of interest in each island. We then calculated the contribution of dispersal syndromes (endozoochory, epizoochory, hydrochory and anemochory) to turnover at each of the scales. Lastly, we assessed the relationship between geographical and climatic distances and habitat type with turnover. Turnover was higher at the smallest spatial scale, particularly in seminatural pastures, and decreased with increasing spatial scales, a pattern potentially associated with the historical fragmentation and current patchy distribution of native forest and seminatural habitats in the Azores. Dispersal syndromes and habitat type had a negligible effect on turnover at all scales. Geographical distance had a positive effect on turnover at all scales, increasing its importance with scale. The relationship between turnover and climatic distance was only significant at the intermediate and small scales in specific islands and habitats. Therefore, scale plays an important role at determining the effect of the drivers of turnover, in particular geographical and climatic distance. These results highlight the need to carefully select the scale of analysis when studying turnover patterns, as well as identifying the potential drivers associated with each spatial scale.info:eu-repo/semantics/publishedVersio

Functional biogeography of oceanic islands and the scaling of functional diversity in the Azores

Analyses of species-diversity patterns of remote islands have been crucial to the development of biogeographic theory, yet little is known about corresponding patterns in functional traits on islands and how, for example, they may be affected by the introduction of exotic species. We collated trait data for spiders and beetles and used a functional diversity index (FRic) to test for nonrandomness in the contribution of endemic, other native (also combined as indigenous), and exotic species to functional-trait space across the nine islands of the Azores. In general, for both taxa and for each distributional category, functional diversity increases with species richness, which, in turn scales with island area. Null simulations support the hypothesis that each distributional group contributes to functional diversity in proportion to their species richness. Exotic spiders have added novel trait space to a greater degree than have exotic beetles, likely indicating greater impact of the reduction of immigration filters and/or differential historical losses of indigenous species. Analyses of species occurring in native-forest remnants provide limited indications of the operation of habitat filtering of exotics for three islands, but only for beetles. Although the general linear (not saturating) pattern of trait-space increase with richness of exotics suggests an ongoing process of functional enrichment and accommodation, further work is urgently needed to determine how estimates of extinction debt of indigenous species should be adjusted in the light of these findings

Systèmes de surveillance automatique en usinage : moyens et méthodes

Les exigences industrielles et économiques actuelles conduisent les entreprises manufacturières à surveiller, d’une manière fiable et précise, les conditions de réalisation et/ou de fabrication des produits et essentiellement celles liées à l’obtention des pièces par enlèvement de matière. Des systèmes de surveillance automatique d’usinage se révèlent indispensables au bon fonctionnement et à la sécurité du processus de fabrication. Ces derniers favorisent une meilleure qualité des pièces et une productivité optimale. Ce processus de surveillance (de monitoring) s’appuie sur le traitement d’un signal acquis en temps réel lors de la fabrication. Ce signal est basé sur des critères scientifiques qui garantissent une efficacité maximale des informations enregistrées. Dans ce contexte, la présente contribution se propose de présenter une revue des différents résultats issus des travaux expérimentaux portant sur ces systèmes de monitoring. Une première partie de cette communication aura pour objet la présentation des méthodes employées dans la surveillance automatique de la production par usinage des métaux. Plus spécifiquement, nous aborderons les différentes approches de diagnostic à la base des modèles développés par la communauté scientifique. Notre intérêt portera sur l’étude des diagnostics des systèmes industriels et sur les objectifs scientifiques et industriels traitant le système de surveillance afin de détecter précocement toute déviation de comportement de la machine ou de l’outil. Une deuxième partie de cette communication sera consacrée à la mise en situation d’un projet de recherche en cours. Ce projet que nous entreprenons vise la conception et la modélisation d’un système de diagnostic en temps réel de l’usure des outils de coupe en tournage. Ce système envisagé suite à un travail expérimental vise l’évaluation ainsi que la prévention de ces défaillances lors d’une opération de fabrication

Arthropod co-occurrence networks indicate environmental differences between islands and signal introduced species in Azorean native forest remnants

Island biotas are in imminent threat from anthropogenic impacts. Of these impacts, the negative effects of exotic species on the taxonomic and functional diversity of the local fauna are of major concern. Exotics may also have a detrimental effect on interspecific interactions which, in turn, can destabilize ecological networks. Species co-occurrence networks can detect species-to-species associations and are used to predict ecological interaction networks and utilized as tools to assess environmental impacts on community structure. Here, we aim to investigate whether or not topological differences of the arthropod co-occurrence networks among native forest fragments from seven Azorean islands can reveal the influence of the abiotic environment and exotic species on these networks. Co-occurrence networks were sensitive to environmental and community dissimilarities, showing a clear separation between islands and pinpointed differences between indigenous and exotic networks. Most exotics were little connected and exotic networks had a large proportion of unconnected species. The resulting decreased connectance and the increased modularity with the increase of the proportions of exotics in the networks suggest that most exotics have too low prevalence to show associations with other species, and only a few dominants drive co-occurrences. The proportion of negative links, as indicators of competition, did not increase with the increase of exotics in the habitats, suggesting that exotics provided new functional roles when they colonized native forest remnants. However, when the theoretical networks consisting of only indigenous species were investigated, connectance decreased and closeness increased with the increase of exotics, suggesting processes of network degradation. Since our study provides ample evidence for the usefulness of co-occurrence network analysis in studying island ecosystems, we recommend the use of this tool for ecosystem assessments, early warning systems and decision-making in island biodiversity conservation.info:eu-repo/semantics/publishedVersio

Power-law scaling in intratumoral microbiota of colorectal cancer

It has recently been proposed that the study of microbial dynamics in humans may gain insights from island biogeographical theory. Here, we test whether the diversity of the intratumoral microbiota of colorectal cancer tumors (CRC) follows a power law with tumor size akin to the island species-area relationship. We confirm a direct correlation between the quantity of Amplicon Sequence Variants (ASVs) within CRC tumors and tumor sizes, following a (log)power model, explaining 47% of the variation. Understanding the processes involved, potentially through the analogy of tumors and islands, may ultimately contribute to future clinical and therapeutic strategies

Power-law scaling in intratumoral microbiota of colorectal cancer

It has recently been proposed that the study of microbial dynamics in humans may gain insights from island biogeographical theory. Here, we test whether the diversity of the intratumoral microbiota of colorectal cancer tumors (CRC) follows a power law with tumor size akin to the island species-area relationship. We confirm a direct correlation between the quantity of Amplicon Sequence Variants (ASVs) within CRC tumors and tumor sizes, following a (log)power model, explaining 47% of the variation. Understanding the processes involved, potentially through the analogy of tumors and islands, may ultimately contribute to future clinical and therapeutic strategies

Taxonomic and functional diversity of insect herbivore assemblages associated with the canopy-dominant trees of the Azorean native forest

Oceanic islands have been providing important insights on the structuring of ecological communities and, under the context of the present biodiversity crisis, they are paramount to assess the effects of biological invasions on community assembly. In this study we compare the taxonomic and functional diversity of insect herbivore assemblages associated with the dominant tree species of Azorean native forests and investigate the ecological processes that may have originated current patterns of plant-herbivore associations. Five dominant trees-Erica azorica, Ilex perado subsp. azorica, Juniperus brevifolia, Laurus azorica and Vaccinium cylindraceum-were sampled in the remnants of the native forest of Terceira Island (Azores) using a standardised methodology. The taxonomic and functional diversity of insect herbivore assemblages was assessed using complementary metrics and beta diversity partitioning analysis (species replacement and richness differences) aiming to evaluate the variation in insect herbivore assemblages within and between the study plant species. Sixty two insect species, mostly bugs (Hemiptera) and caterpillars (Lepidoptera), were found in the five study plants with indigenous (endemic and native non-endemic) insects occurring with higher species richness and abundance than introduced ones. Species replacement was the most important component of insect herbivore taxonomic beta diversity while differences in trait richness played a major role on functional beta diversity. The endemic E. azorica stands out from the other study plants by having associated a very distinct insect herbivore assemblage with a particular set of functional attributes, mainly composed by large bodied and long shaped species that feed by chewing. Despite the progressive biotic homogenization witnessed in the Azores during the last few decades, several strong associations between the endemic trees and their indigenous insect herbivores remain.Peer reviewe