James R. Bell

Arthropod declines have been reported widely, and yet the spotlight has fallen on relatively large, colourful insects, rarely considering the abundant, small‐sized, yet charismatic flying insects and ballooning spiders we class as neglected and undervalued ‘Cinderella species’. This diverse set of arthropods contributes important ecosystem services, such as decomposition, pollination, pest regulation and nutrient cycling. We sampled a 30 year long archived arthropod collection, preserved in ethanol from the daily 12.2 m suction‐trap catches at four sites in the UK, to provide new data on more than 600,000 previously unidentified insects and spiders. Group or family‐level trends for the Coleoptera (beetles), Diptera (true flies), Hemiptera (true bugs) and Hymenoptera (bees, ants and wasps) as well as trends for seemingly less well‐known orders including the Psocoptera (barkflies), Dermaptera (earwigs) and Araneae (spiders) are provided. Our aim is to produce 30 year explainable trends in abundance and phenology for 71 Cinderella arthropod groups, and explore their functional trophic guild and habitat use during the immature stage. We trained random forest models to predict log abundance and phenology (Day of 5% catch) using a set of landscape, topography, weather‐related drivers. We show that the majority of arthropod taxa, as well as most trophic and habitat‐use groups, report either stable or increasing abundances, and stable or earlier phenologies. We also found that across taxa, earlier phenologies (54%–70% of taxa) and more abundant catches (55%–77%) are significantly related. These trends are mostly explained by temperature‐related drivers and secondarily by landcover, of which the strongest signal is improved grassland. Our study establishes a quantitative baseline for an undervalued, forgotten and often sparsely recorded segment of Britain's biodiversity.

Myzus persicae is a medium‐sized aphid that has rapidly become a global crop pest due to its ability to transmit a broad range of plant viruses to a wide range of plant hosts. The aphid is routinely cited as capable of transmitting over 100 different plant viruses. We used historical data to scrutinise each historical virus/viroid record attributed to M. persicae to establish whether it is now considered by the International Committee on Taxonomy of Viruses (ICTV) classification to be a valid ‘biological virus species’ and not a strain, isolate, or common name synonym. We impose ICTV's recently erected Latin binomial classification alongside the common name of each virus to show that M. persicae transmits 196 viruses, drawn exclusively from the Riboviria, and 1 viroid that all use ribonucleic acid (RNA) as their primary genetic material. Most, but not all, viruses are efficiently transmitted. Virus presence in GB matches well with Northwestern European presence. The largest virus group transmitted by M. persicae is the non‐persistent Potyviridae, particularly Potyvirus . No Rhabdoviruses are transmitted. We present a summary of 15 of the world's most impactful agricultural and horticultural viruses vectored by M. persicae , illustrating Tier 1 viruses that have a global impact at a cost of more than $1 Bn pa (e.g., Plum pox virus; Potato virus Y), causing pandemics and epidemics at scale, and Tier 2 viruses that are the cause of significant moderate or high regional or continental impact (e.g., Sugarcane mosaic virus; Watermelon mosaic virus).

Arthropod declines have been reported widely; however, a lack of comprehensive data has hindered our ability to assess their large‐scale generality and drivers. Here, we used a novel and freely available dataset—atmospheric scans from a network of meteorological radars—to quantify aerial abundance of both diurnal and nocturnal arthropods across the United Kingdom, spanning different geographic regions and land cover types. Based on observations between 2014 and 2021, and across more than 35,000 km ² , we estimate numbers of arthropods flying over the UK at heights between 500 and 700 m above ground at 1.12 (±0.01) × 10 ¹³ individuals during the diurnal (0800–1400 UTC) and 5.02 (±0.01) × 10 ¹² during the nocturnal (including dusk, 1800–2200 UTC) period, showing significant spatial heterogeneity. Although spatial patterns differed, both diurnal and nocturnal arthropods increased in the south and declined mainly in the far north; on average, only nocturnal arthropods showed an overall decline. Aerial abundance of both diurnal and nocturnal arthropods showed positive relationships with woodland, grassland, and urban land cover, and negative relationships with artificial light intensity and arable land cover. Our study highlights the importance of spatial variation in temporal biodiversity trends and illustrates the need for comparative studies between nocturnal and diurnal arthropods. Notably, by extracting vertical profiles of radar reflectivity and polarization signatures, we demonstrate how weather radar datasets can be used to quantify aerial arthropod abundance, detect diurnal and seasonal activity patterns, and examine their environmental drivers across large spatial and temporal scales.

Nasonovia ribisnigri (Mosley) is a severe aphid pest of outdoor lettuce, and the combination of sporadic and unpredictable colonization on outdoor lettuce, along with the breakdown of cultivar resistance, has left few effective control methods. The population structure (spatially and temporally) of N. ribisnigri is currently unknown in England, and therefore microsatellite markers were designed to estimate the impacts of host plant selection pressure (including host plant resistance) and environmental change. Biological samples collected between 2003 and 2020 from 10 sites across England were typed with microsatellite markers. The analysis of 8 microsatellites indicated a clear east-west divide between N. ribisnigri populations, which corresponds with current outdoor lettuce cultivation distribution in England, one of the aphid’s summer hosts. Analysis of gene flow indicated that aphids did not leave the eastern region; instead, there was strong evidence for aphids migrating from the West into the secondary host eastern region, possibly from the winter host (Ribes spp.) in Spring. This result suggests that although N. ribisnigri has the potential for long-distance migration, strong ties to the summer host (lettuce) determine migratory behavior at the population level. N. ribisnigri are mostly holocyclic and show a high level of inbreeding. Long-term trends revealed relatively stable populations, despite a recent breakdown of host plant resistance and other environmental changes, including favorable temperatures. The geographic and temporal structure of the N. ribisnigri population is discussed in relation to future pest management strategies.

Consumers are thought to select food resources based on their nutritional content. While laboratory experiments have explored this, the nutritional dynamics of invertebrate predators have been scarcely studied in the field given various methodological constraints. The intersection of these nutritional dynamics with predator traits is also poorly characterised, leading to many gaps in our understanding of how different predators forage and feed in natural systems. Here, we integrate dietary metabarcoding with prey macronutrient (protein, lipid and carbohydrate) content and abundance to assess how nutrients and predator traits (sex, life stage and taxonomy) interactively drive prey preferences in the field, using spider–prey interactions as a model system. Different spider genera, sexes and life stages had nutritionally distinct diets. Our analyses demonstrated disproportionate foraging (selection and avoidance) for prey rich in different macronutrients, with the nature of these relationships differing between spider taxa, life stages and sexes. This may be explained by niche differentiation among spider groups, driven by biases toward prey rich in different nutrients, or nutrient‐specific foraging in which individual spiders vary their nutritional preferences to redress deficits, although further evidence is required to confirm this. This insight into the nutritional dynamics of generalist invertebrate predators extends our understanding beyond lab‐based behavioural assays and provides a novel framework for other complex real‐world systems.

Insect populations are declining in many parts of the world, but a lack of long‐term monitoring data is impeding our ability to understand and mitigate the causes of insect biodiversity loss. Whilst high‐throughput sequencing (HTS) approaches, such as DNA metabarcoding, have the potential to revolutionize insect biomonitoring through rapid scalable identification, it is unclear to what extent HTS can be applied to long‐term stored insect samples. Archived insect samples could inform forecasting and provide valuable information regarding past changes to biodiversity. Here, we assess the efficacy of DNA metabarcoding to identify archived samples from the longest passive monitoring scheme in the United Kingdom: the Rothamsted Insect Survey (RIS). With a focus on aphids as the target taxa of a national network of suction‐traps, we analyze a 16‐year time‐series of stored samples (2003–2018) using DNA metabarcoding from one of the RIS suction traps as an exemplar. We achieved this by using a non‐destructive DNA extraction protocol, ensuring the integrity of archival samples for further studies. We compared the identities of aphids determined by both metabarcoding (as inferred amplicon sequence variants [ASVs]) and morphological identification and found that metabarcoding detected most genera with varying success (mean > 76%). When comparing the two methods objectively (i.e., including taxa not detected morphologically), however, congruence decreased (51%). We show that minimum sequence copy thresholds can minimize metabarcoding false positives, but at the expense of introducing false negatives, highlighting the need for careful data curation. Detectability of taxa identified morphologically and similarity between the two methods did not significantly vary over time, demonstrating the viability of metabarcoding for screening archival samples. We discuss the advantages and challenges of metabarcoding for insect biomonitoring, particularly from archival samples, including improvements to sample handling, processing, and archiving. We highlight the wider potential of HTS approaches for stored samples from insect monitoring schemes, unlocking the immense potential of global historical time series.

Aphid genomic resources enable the study of complex life history traits and provide information on vector biology, host adaption and speciation. The currant–lettuce aphid ( Nasonovia ribisnigri (Hemiptera: Aphididae ) (Mosley)) is a cosmopolitan pest of outdoor lettuce ( Lactuca sativa (Asterales: Asteraceae) (Linnaeus)). Until recently, the use of resistant cultivars was an effective method for managing N . ribisnigri . A resistant cultivar containing a single gene (Nr‐locus), introduced in the 1980s, conferred complete resistance to feeding. Overreliance of this Nr‐locus in lettuce resulted in N . ribisnigri's ability to break resistance mechanism, with first reports during 2003. Our work attempts to understand which candidate gene(s) are associated with this resistance‐breaking mechanism. We present two de novo draft assembles for N . ribisnigri genomes, corresponding to both avirulent (Nr‐locus susceptible) and virulent (Nr‐locus resistant) biotypes. Changes in gene expression of the two N . ribisnigri biotypes were investigated using transcriptomic analyses of RNA‐sequencing (RNA‐seq) data to understand the potential mechanisms of resistance to the Nr‐locus in lettuce. The draft genome assemblies were 94.2% and 91.4% complete for the avirulent and virulent biotypes, respectively. Out of the 18,872 differentially expressed genes, a single gene/locus was identified in N . ribisnigri that was shared between two resistant‐breaking biotypes. This locus was further explored and validated in Real‐Time Quantitative Reverse Transcription PCR (qRT‐PCR) experiments and has predicted localisations in both the cytoplasm and nucleus. This is the first study to provide evidence that a single gene/locus is likely responsible for the ability of N . ribisnigri to overcome the Nr‐locus resistance in the lettuce host.

Null models provide an invaluable baseline against which to test fundamental ecological hypotheses and highlight patterns in foraging choices that cannot be explained by neutral processes or sampling artefacts. In this way, null models can advance our understanding beyond simplistic dietary descriptions to identify drivers of interactions. This method, however, requires estimates of resource availability, which are generally imperfect representations of highly dynamic systems. Optimising method selection is crucial for study design, but the precise effects of different resource availability data on the efficacy of null models are poorly understood. Using spider-prey networks as a model, we used prey abundance (suction sample) and activity density (sticky trap) data, and combinations of the two, to simulate null networks. We compared null diet composition, network properties (e.g., connectance and nestedness) and deviations of simulations from metabarcoding-based spider dietary data (to ascertain how different prey availability data alter ecological interpretation. Different sampling methods produced different null networks and inferred distinct prey selectivity. Null networks based on prey abundance and combined frequency-of-occurrence data more closely resembled the observed diet composition, and those based on prey abundance, activity density and proportionally combined data generated network properties most like dietary metabarcoding networks. We show that survey method choice impacts all aspects of null network analyses, the precise effects varying between methods but ultimately altering ecological interpretation by increasing disparity in network properties or trophic niches between null and directly constructed networks. Merging datasets can generate more complete prey availability data but is not a panacea because it introduces different biases. The choice of method should reflect the research hypotheses and study system being investigated. Ultimately, survey methods should emulate the foraging mode of the focal predator as closely as possible, informed by the known ecology, natural history and behaviour of the predator.

Generalist invertebrate predators are sensitive to weather conditions, but the relationship between their trophic interactions and weather is poorly understood. This study investigates how weather affects the identity and frequency of spider trophic interactions over time, alongside prey community structure, web characteristics and prey choice. Spiders (Linyphiidae and Lycosidae) and their prey were collected from barley fields in Wales, UK, from April to September 2017–2018. The gut contents of 300 spiders were screened using DNA metabarcoding, analysed via multivariate models and compared against prey availability using null models. When linyphiids were collected from webs, the height and area of webs were recorded and compared against weather conditions. Trophic interactions changed over time and with weather conditions, primarily related to concomitant changes in prey communities. Spiders did, however, appear to mitigate the effects of structural changes in prey communities through changing prey preferences according to prevailing weather conditions, possibly facilitated by adaptive web construction. Using these findings, we demonstrate that prey choice data collected under different weather conditions can be used to refine inter‐annual predictions of spider trophic interactions, although prey abundance was secondary to diversity in driving the diet of these spiders. By improving our understanding of the interaction between trophic interactions and weather, we can better predict how ecological networks are likely to change over time in response to variation in weather conditions and, more urgently, global climate change.

BACKGROUND: The pollen beetle (Brassicogethes aeneus) causes significant yield loss in oilseed rape (Brassica napus). Predicting population changes remains a scientific challenge, especially since its phenology and abundance varies dramatically over space and time. We used generalized additive models to investigate the long‐term trends in pollen beetle annual, seasonal and monthly counts from Rothamsted 12.2 m suction‐traps. We hypothesised that the beetle's abundance is positively related to the area of oilseed rape at a national and regional level. We used random forest models to investigate the inter‐generational relationship within years.RESULTS: Although Brassicogethes aeneus annual counts and area of oilseed rape grown in the UK both increased by 162% and 113%, respectively, over the time period studied, they were not significantly related. The size of the immigrating pollen beetle population (up to 1 June) can be explained both by the size of the population in the previous summer and prevailing winter temperatures, indicating a positive feedback mechanism.CONCLUSION: Currently, pollen beetle numbers continue to increase in the UK, meaning that control issues may persist. However the relationship between counts in spring, during the susceptible phase of the crop, and counts in the previous summer indicates that it may be possible to forecast the counts of the spring migration of Brassicogethes aeneus a few months in advance using suction‐trap samples, which could aid decisions on control options. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.