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- Cumulative impact assessments of multiple host species loss from plant diseases show disproportionate reductions in associated biodiversityPublication . Mitchell, Ruth J.; Bellamy, Paul E.; Broome, Alice; Ellis, Chris J.; Hewison, Richard L.; Iason, Glenn R.; Littlewood, Nick A.; Newey, Scott; Pozsgai, Gabor; Ray, Duncan; Stockan, Jenni A.; Stokes, Victoria; Taylor, Andy F. S.Non-native plant pests and pathogens are increasing exponentially, causing extirpation of foundation species. The impact of large-scale declines in a single host on associated biodiversity is widely documented. However, the impact of multiple host loss on biodiversity and whether these impacts are multiplicative has not been assessed. Ecological theory suggests that systems with greater functional redundancy (alternative hosts) will be more resilient to the loss of sympatric hosts. We test this theory and show its importance in relation to pest/pathogen impact assessments. We assessed the potential impact on biodiversity of the loss of two widely occurring sympatric European tree species, Fraxinus excelsior and Quercus petraea/robur, both of which are currently threatened by a range of pests and pathogens. At the UK scale, the total number of associated species at risk of extirpation from plant diseases affecting these two sympatric hosts is greater than the sum of the associated species at risk from declines in either host alone. F. excelsior hosts 45 obligate species (species only found on that host) and Q. petraea/robur hosts 326. However, a decline in both these trees would impact 512 associated species, across multiple taxon groups, a 38% increase. Assessments at a local scale, 24 mixed F. excelsior–Q. petraea/robur woodlands revealed that these impacts may be even greater due to a lack of functional redundancy. Only 21% of sites were able to provide functional redundancy for F. excelsior and Q. petraea/robur associated species which can use other tree species. In most woodlands, the tree species required to provide functional redundancy were not present, although the site conditions were often suitable for them to grow. Synthesis. Understanding of functional redundancy should be applied to assessments of pests/pathogens impact on biodiversity. In risk assessments, higher impact scores should be given to pests/pathogens affecting hosts occurring with other host plant species already impacted by pests/pathogens. Current pest/pathogen risk assessment approaches that ignore the cumulative, cascading effects shown in this study may allow an insidious, mostly overlooked, driver of biodiversity loss to continue.
- Gut microbiota assemblages of generalist predators are driven by local- and landscape-scale factorsPublication . Saqib, Hafiz Sohaib Ahmed; Sun, Linyang; Pozsgai, Gabor; Liang, Pingping; Goraya, Mohsan Ullah; Akutse, Komivi Senyo; You, Minsheng; Gurr, Geoff M.; You, ShijunABSTRACT: The gut microbiomes of arthropods have significant impact on key physiological functions such as nutrition, reproduction, behavior, and health. Spiders are diverse and numerically dominant predators in crop fields where they are potentially important regulators of pests. Harnessing spiders to control agricultural pests is likely to be supported by an understanding of their gut microbiomes, and the environmental drivers shaping microbiome assemblages. This study aimed to deciphering the gut microbiome assembly of these invertebrate predators and elucidating potential implications of key environmental constraints in this process. Here, we used high-throughput sequencing to examine for the first time how the assemblages of bacteria in the gut of spiders are shaped by environmental variables. Local drivers of microbiome composition were globally-relevant input use system (organic production vs. conventional practice), and crop identity (Chinese cabbage vs. cauliflower). Landscape-scale factors, proportion of forest and grassland, compositional diversity, and habitat edge density, also strongly affected gut microbiota. Specific bacterial taxa were enriched in gut of spiders sampled from different settings and seasons. These findings provide a comprehensive insight into composition and plasticity of spider gut microbiota. Understanding the temporal responses of specific microbiota could lead to innovative strategies development for boosting biological control services of predators.
- DNA metabarcoding of gut contents reveals key habitat and seasonal drivers of trophic networks involving generalist predators in agricultural landscapesPublication . Saqib, Hafiz Sohaib Ahmed; Sun, Linyang; Pozsgai, Gabor; Liang, Pingping; You, Minsheng; Gurr, Geoff M.; You, ShijunBACKGROUND: Understanding the networks of trophic interactions into which generalist predators are embedded is key to assessing their ecological role of in trophic networks and the biological control services they provide. The advent of affordable DNA metabarcoding approaches greatly facilitates quantitative understanding of trophic networks and their response to environmental drivers. Here, we examine how key environmental gradients interact to shape predation by Lycosidae in highly dynamic vegetable growing systems in China. RESULTS: For the sampled Lycosidae, crop identity, pesticide use and seasons shape the abundance of prey detected in spider guts. For the taxonomic richness of prey, local- and landscape-scale factors gradients were more influential. Multivariate ordinations confirm that these crop-abundant spiders dynamically adjust their diet to reflect environmental constraints and seasonal availability to prey. CONCLUSION: Plasticity in diet composition is likely to account for the persistence of spiders in relatively ephemeral brassica crops. Our findings provide further insights into the optimization of habitatmanagement for predator-based biological control practices.
- Associations between carabid beetles and fungi in the light of 200 years of published literaturePublication . Pozsgai, Gabor; Ben Fekih, Ibtissem; Kohnen, Markus V.; Amrani, Said; Bérces, Sándor; Fülöp, Dávid; Jaber, Mohammed Y. M.; Meyling, Nicolai Vitt; Ruszkiewicz-Michalska, Malgorzata; Pfliegler, Walter P.; Sánchez-García, Francisco Javier; Zhang, Jie; Rensing, Christopher; Lövei, Gábor L.; You, MinshengDescribing and conserving ecological interactions woven into ecosystems is one of the great challenges of the 21st century. Here, we present a unique dataset compiling the biotic interactions between two ecologically and economically important taxa: ground beetles (Coleoptera: Carabidae) and fungi. The resulting dataset contains the carabid-fungus associations collected from 392 scientific publications, 129 countries, mostly from the Palearctic region, published over a period of 200 years. With an updated taxonomy to match the currently accepted nomenclature, 3,378 unique associations among 5,564 records were identified between 1,776 carabid and 676 fungal taxa. Ectoparasitic Laboulbeniales were the most frequent fungal group associated with carabids, especially with Trechinae. The proportion of entomopathogens was low. Three different formats of the data have been provided along with an interactive data digest platform for analytical purposes. Our database summarizes the current knowledge on biotic interactions between insects and fungi, while offering a valuable resource to test large-scale hypotheses on those interactions.
- Contrasting roles of landscape compositions on shaping functional traits of arthropod community in subtropical vegetable fieldsPublication . Zhang, Jie; Saqib, Hafiz Sohaib Ahmed; Niu, Dongsheng; Guaman, Karla Giovana Gavilanez; Wang, Ao; Yu, Deyi; You, Minsheng; Pozsgai, Gabor; You, ShijunAgricultural intensification and land use transformation are among the main driving forces of the unprecedented decline of biodiversity and ecosystem services in croplands. Trait-based approaches provide a unique framework to detect the potential mechanisms of how this intensification affects biodiversity and alter ecosystem services. However, the potential relationship between arthropod traits and various types of habitats is still poorly understood, especially in subtropical vegetable agroecosystems. Here, we conducted a trait-based approach to evaluate the variable roles of different habitats on functional trait diversity and the structure of the arthropod community in brassica vegetable crops. Twenty-three conventional cruciferous vegetables fields were sampled over two years in three regions in Fujian, China. We found that the increasing proportion of non-brassica vegetable plantations and water bodies negatively affected the functional diversity of arthropods, whereas forest and grassland habitats showed a positive correlation, indicating habitat filtering for certain traits or trait combinations. This study demonstrates the importance of landscape composition as an ecological filter for vegetable arthropod community, and identifies how the proportion of different habitats selected for or against specific functional traits. Our findings support that increasing forest and grassland areas adjacent to vegetable fields can play a vital role in promoting the functional diversity of arthropod communities. Since the natural enemy assemblages supported by these habitats bear combinations of diverse traits adapted to disturbance, they have the potential to enhance pest suppression in the highly variable environment of vegetable crops.
- Edge effects constrain endemic but not introduced arthropod species in a pristine forest on Terceira (Azores, Portugal)Publication . Tsafack, Noelline; Pozsgai, Gabor; Boieiro, Mário; Ros-Prieto, Alejandra; Nunes, Rui; Ferreira, Maria Teresa; Borges, Paulo A. V.Pristine Azorean forests have been deeply fragmented since human colonization. Fragmentation increases the length of edges and it therefore promotes edge habitats. Studying the impact of edge habitat on species assemblages is crucial to highlight the importance of forest connectivity and guide management strategies. This study explores the impact of forest edges on arthropod assemblages, and particularly investigates the differences of arthropod communities between three habitats, along a distance gradient from the forest edge near a pasture matrix to the core forest. We also compare patterns of arthropod communities with different biogeographic status (endemic, native non-endemic, and introduced species), given the island context. We sampled in a pristine forest on Terceira Island bordered by semi-natural pastures, using flight interception traps. Overall, endemic species dominated arthropod abundances whereas species richness and diversity were similar between the three biogeographic categories. We found evidence of a strong edge effect on arthropod assemblages, adjusted both by biogeographic categories and seasonality. Indigenous (endemic and native non-endemic) species abundances were higher in the forest interior than at the edges or intermediate habitats, suggesting that indigenous arthropod assemblages were sensitive to the distance from the edge, a distance extended over 100 m to the core forest, whereas introduced species abundances were not impacted. Species diversity and richness did not differ between the three habitats either, regardless of the biogeographic categories. The composition of arthropods between the three habitats differed significantly when we considered all species or endemic species only, but not with native non-endemic or introduced species. However, the difference got obscured when seasonality was included in the analyses, suggesting that even though edges impact species composition, this impact varies seasonally and endemic species are particularly affected in early summer. Our results indicate that forest edges impact arthropods assemblages but endemic species are more likely to be constrained by the increase of edges than introduced species. Since most of these endemic species are of conservation concern, we urge to avoid forest management strategies that increase fragmentation and call for action to increase the size of protected natural parks.
- Effects of cover crops on beetle assemblages in tea plantationsPublication . Chen, Li-Lin; Pozsgai, Gabor; Li, Xiang-Yu; Li, Lei; Reddy, Gadi V. P.; You, Min-ShengColeoptera are visible members of food webs in tea plantations, with high species richness and abundance. Many tea pests, as well as natural enemies, are members of this order, so a knowledge of how groundcovers affect beetles can aid pest management. We collected beetles in a replicated field experiment in the Wuyi Mountains, Fujian Province, China. Tea was intercropped with Paspalum notatum or Chamaecrista rotundifolia, or rows were cleared to bare ground, or in the control they were left unmanaged to allow weeds to grow naturally. Sampling, done by sweep netting and vegetation beating, was conducted monthly, between May 2006 and April 2008, and Coleoptera abundance, biomass, species richness and assemblage structures were compared between groundcover treatments. Total beetle abundance and species richness were significantly higher in tea intercropped with C. rotundifolia and bare ground than in naturally grown weedy control. Whilst there was no difference between predator assemblages among treatments for any measure, herbivores were more abundant, weighed more, and were more diverse in C. rotundifolia treatments than in weedy control. Biomass and species richness were also greater in plots with P. notatum groundcover than those in weedy control. We found that beetle assemblages varied both seasonally and with ground cover treatment, but the potential pest control impact of more species-rich beetle assemblages was mixed, and further work is needed to gain information on trophic groups with potential benefits for use in non-insecticidal pest management.
- Island and Mountain Ecosystems as Testbeds for Biological Control in the AnthropocenePublication . Wyckhuys, Kris A. G.; Sanchez Garcia, Francisco J.; Santos, Ana M. C.; Canal, Nelson A.; Furlong, Michael J.; Melo, Maria C.; GC, Yubak Dhoj; Pozsgai, GaborFor centuries, islands and mountains have incited the interest of naturalists, evolutionary biologists and ecologists. Islands have been the cradle for biogeography and speciation theories, while mountain ranges have informed how population adaptation to thermal floors shapes the distribution of species globally. Islands of varying size and mountains’ altitudinal ranges constitute unique “natural laboratories” where one can investigate the effects of species loss or global warming on ecosystem service delivery. Although invertebrate pollination or seed dispersal processes are steadily being examined, biological control research is lagging. While observations of a wider niche breadth among insect pollinators in small (i.e., species-poor) islands or at high (i.e., colder) altitudes likely also hold for biological control agents, such remains to be examined. In this Perspective piece, we draw on published datasets to show that island size alone does not explain biological control outcomes. Instead, one needs to account for species’ functional traits, habitat heterogeneity, host community make-up, phenology, site history or even anthropogenic forces. Meanwhile, data from mountain ranges show how parasitism rates of Noctuid moths and Tephritid fruit flies exhibit species- and context-dependent shifts with altitude. Nevertheless, future empirical work in mountain settings could clarify the thermal niche space of individual natural enemy taxa and overall thermal resilience of biological control. We further discuss how global databases can be screened, while ecological theories can be tested, and simulation models defined based upon observational or manipulative assays in either system. Doing so can yield unprecedented insights into the fate of biological control in the Anthropocene and inform ways to reinforce this vital ecosystem service under global environmental change scenarios.
- Grazing impacts on ground beetle (Coleoptera: Carabidae) abundance and diversity on semi‐natural grasslandPublication . Pozsgai, Gabor; Quinzo‐Ortega, Luis; Littlewood, Nick A.Semi-natural grasslands are commonly managed as a grazing resource for domestic livestock but, due to their unique biodiversity, they are also of conservation interest. Numerous drivers have impacted on the status of these grasslands in recent decades, most importantly changing grazing management strategies. These changes have the potential to affect the biodiversity associated with these habitats, including on some rich invertebrate assemblages. Responses, however, are often dissimilar between different invertebrate taxa. We investigated the responses of ground beetles to different grazing regimes within a replicated, controlled, long-term grazing experiment on upland semi-natural grassland in Scotland. Although there was substantial overlap of species composition of ground beetle assemblages in different grazing treatments, species richness, abundance and Shannon diversity of ground beetles were significantly lower in ungrazed plots than in plots subject to high- or low-intensity sheep grazing. Ground beetle abundance (but not species richness or diversity) was lower in ungrazed plots compared to those with low-intensity mixed grazing by sheep and cattle. However, no differences were identified in abundance, species richness or diversity between the three grazed treatments. Our results suggest that ground beetles may show different responses to grazing compared to responses of some other invertebrate groups and demonstrate the difficulty of attempting to manage grazing to optimise conditions for a wide range of invertebrates.
- Flower Visitation through the Lens: Exploring the Foraging Behaviour of Bombus terrestris with a Computer Vision-Based ApplicationPublication . Varga-Szilay, Zsófia; Szövényi, Gergely; Pozsgai, GaborTo understand the processes behind pollinator declines and for the conservation of pollination services, we need to understand fundamental drivers influencing pollinator behaviour. Here, we aimed to elucidate how wild bumblebees interact with three plant species and investigated their foraging behaviour with varying flower densities. We video-recorded Bombus terrestris in 60 × 60 cm quadrats of Lotus creticus, Persicaria capitata, and Trifolium pratense in urban areas of Terceira (Azores, Portugal). For the automated bumblebee detection and counting, we created deep learning-based computer vision models with custom datasets. We achieved high model accuracy of 0.88 for Lotus and Persicaria and 0.95 for Trifolium, indicating accurate bumblebee detection. In our study, flower cover was the only factor that influenced the attractiveness of flower patches, and plant species did not have an effect. We detected a significant positive effect of flower cover on the attractiveness of flower patches for flower-visiting bumblebees. The time spent per unit of inflorescence surface area was longer on the Trifolium than those on the Lotus and Persicaria. However, our result did not indicate significant differences in the time bumblebees spent on inflorescences among the three plant species. Here, we also justify computer vision-based analysis as a reliable tool for studying pollinator behavioural ecology.
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