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We report the results of an experiment on radio-tracking of individual grey field slugs in an arable field and associated data modelling designed to investigate the effect of slug population density in their movement. Slugs were collected in a commercial winter wheat field in which a 5x6 trapping grid had been established with 2m distance between traps. The slugs were taken to the laboratory, radio-tagged using a recently developed procedure, and following a recovery period released into the same field. Seventeen tagged slugs were released singly (sparse release) on the same grid node on which they had been caught. Eleven tagged slugs were released as a group (dense release). Each of the slugs was radio-tracked for approximately 10 h during which their position was recorded ten times. The tracking data were analysed using the Correlated Random Walk framework. The analysis revealed that all components of slug movement (mean speed, turning angles and movement/resting times) were significantly different between the two treatments. On average, the slugs released as a group disperse more slowly than slugs released individually and their turning angle has a clear anticlockwise bias. The results clearly suggest that population density is a factor regulating slug movement.

The objective of this study was to identify the aggregation pheromone of the melon thrips Thrips palmi, a major pest of vegetable and ornamental plants around the world. The species causes damage both through feeding activities and as a vector of tospoviruses, and is a threat to world trade and European horticulture. Improved methods of detecting and controlling this species are needed and the identification of an aggregation pheromone will contribute to this requirement. Bioassays with a Y-tube olfactometer showed that virgin female T. palmi were attracted to the odour of live males, but not to that of live females, and that mixed-age adults of both sexes were attracted to the odour of live males, indicating the presence of a male-produced aggregation pheromone. Examination of the headspace volatiles of adult male T. palmi revealed only one compound that was not found in adult females. It was identified by comparison of its mass spectrum and chromatographic details with those of similar compounds. This compound had a structure like that of the previously identified male-produced aggregation pheromone of the western flower thrips Frankliniella occidentalis. The compound was synthesised and tested in eggplant crops infested with T. palmi in Japan. Significantly greater numbers of both males and females were attracted to traps baited with the putative aggregation pheromone compared to unbaited traps. The aggregation pheromone of T. palmi is thus identified as (R)-lavandulyl 3-methyl-3-butenoate by spectroscopic, chromatographic and behavioural analysis.

Factors and processes determining heterogeneous (‘patchy’) population distributions in natural environments have long been a major focus in ecology. Existing theoretical approaches proved to be successful in explaining vegetation patterns. In the case of animal populations, existing theories are at most conceptual: they may suggest a qualitative explanation but largely fail to explain patchiness quantitatively. We aim to bridge this knowledge gap. We present a new mechanism of self-organized formation of a patchy spatial population distribution. A factor that was under-appreciated by pattern formation theories is animal sociability, which may result in density dependent movement behaviour. Our approach was inspired by a recent project on movement and distribution of slugs in arable fields. The project discovered a strongly heterogeneous slug distribution and a specific density dependent individual movement. In this paper, we bring these two findings together. We develop a model of density dependent animal movement to account for the switch in the movement behaviour when the local population density exceeds a certain threshold. The model is fully parameterized using the field data. We then show that the model produces spatial patterns with properties closely resembling those observed in the field, in particular to exhibit similar values of the aggregation index.

Attempts to mitigate the computational cost of fully resolved large-eddy simulation (LES) in the near-wall region include both the hybrid Reynolds-averaged Navier–Stokes/LES (HRL) and wall-modeled LES (WMLES) approaches. This paper presents an LES wall treatment method that combines key attributes of the two, in which the boundary layer mesh is sized in the streamwise and spanwise directions comparable to WMLES, and the wall-normal mesh is comparable to a RANS simulation without wall functions. A mixing length model is used to prescribe an eddy viscosity in the near-wall region, with the mixing length scale limited based on local mesh size. The RANS and LES regions are smoothly blended using the dynamic hybrid RANS-LES (DHRL) framework. The results are presented for the turbulent channel flow at two Reynolds numbers, and comparison to the DNS results shows that the mean and fluctuating quantities are reasonably well predicted with no apparent log-layer mismatch. A detailed near-wall meshing strategy for the proposed method is presented, and estimates indicate that it can be implemented with approximately twice the number of grid points as traditional WMLES, while avoiding the difficulties associated with analytical or numerical wall functions and modified wall boundary conditions.

Deroceras reticulatum in arable fields display spatio-temporally stable slug patches that have been well documented under typical soil moisture conditions. The effect of abnormally high soil moisture on slug patch stability, however, is unknown. In this study, stepped gradient choice tests comparing soil moisture levels of 50–125% soil capacity showed slug preferences for levels in a range near to 125%. Activity became erratic, however, when given a choice of high moisture levels (125–370%), potentially because slugs searched for preferred conditions. Slug spatial aggregation was investigated in 21 commercial fields in 2023/24, a season of extreme rainfall, and then compared to years exhibiting typical rainfall (2015–2018). Slug patches occurred in 27.2% of assessment visits to fields during 2023/24 compared to 96.4% in typical years, suggesting weather conditions leading to abnormally high soil moisture are significantly associated with the breakdown of slug spatial aggregation behaviour. Random forest models identified the weather predictors (precipitation, relative humidity, temperature) with the highest impact on slug distribution and relative abundance, with the assessment date and region also related to relative abundance. However, a complex of environmental parameters affects soil moisture content, and no statistically significant effects of individual weather predictors emerged. The results are discussed in relation to slug behaviour in the context of their impact on targeted slug treatments.

Performance of Osmia bicornis larvae fed on six diets with different pollen species composition (one wild collected by foraging adults), each with known levels of nine essential amino acids (EAA; leucine, lysine, valine, arginine, isoleucine, phenylalanine, threonine, histidine, methionine), was investigated. Four of the pollen diets consisted of individual pollen species and two were mixtures of either four or five species (including one naturally foraged by adult O. bicornis). The diets fell into four statistically distinct groups with different EAA contents (ranked from Group I (highest EAA) to Group IV (lowest EAA; pine pollen). The highest larval survival rate was recorded with the wild-foraged diet (Group III) with no survival in Group IV. Similar survival occurred for all other diets. Where larvae survived (Group I–III), there was no effect of diet on the time to commencement of larval stages, cocoon completion or larval development time (egg hatch to pupation), or on pupal weight. The findings provide corroborative evidence of the existence of amino acid thresholds for larval success, but the need for further work is discussed in relation to their multidimensional nutritional requirements and variation of the nutritional content of pollen.

The Routledge Handbook of Arabic and Identity offers a comprehensive and up-to-date account of studies that relate the Arabic language in its entirety to identity. This handbook offers new trajectories in understanding language and identity more generally and Arabic and identity in particular. Split into three parts, covering ‘Identity and Variation’, ‘Identity and Politics’ and ‘Identity Globalisation and Diversity’, it is the first of its kind to offer such a perspective on identity, linking the social world to identity construction and including issues pertaining to our current political and social context, including Arabic in the diaspora, Arabic as a minority language, pidgin and creoles, Arabic in the global age, Arabic and new media, Arabic and political discourse. Scholars and students will find essential theories and methods that relate language to identity in this handbook. It is particularly of interest to scholars and students whose work is related to the Arab world, political science, modern political thought, Islam and social sciences including: general linguistics, sociolinguistics, discourse analysis, anthropological linguistics, anthropology, political science, sociology, psychology, literature media studies and Islamic studies.

Climate change and the withdrawal of several classes of agrochemicals from use are intensifying the challenges faced by food producers in controlling pests in crop systems. Integrated pest management (IPM), which uses a combination of pest control approaches, is therefore a focus in international initiatives to improve the resilience of food production. Integrating the greater use of trees and shrubs on farms within IPM frameworks offers a biodiversity‐positive contribution to crop protection. For example, trees can modulate the prevalence and impacts of agricultural pests and their natural antagonists through direct and indirect interactions. The beneficial impact of farmland trees and shrubs on pest management in arable or grassland fields can be enhanced from an analysis of variables such as tree species and their spatial distribution on farms, insect‐plant dynamics, population behaviours and soil management practices. The aim of this study is to synthesise existing knowledge and to assess the benefits and trade‐offs between farmland trees and IPM strategies, building on gaps in knowledge identified by a stakeholder survey. Through this targeted review, we delineate the future evidence required to define and quantify the advantages that farmland trees offer as an element of IPM strategies. Practical implication. The development of regional biodiversity monitoring tools, which integrate landscape features such as trees, shows promise for shaping national policies to increase the adoption of IPM. There is a demand for user‐friendly on‐farm tools, adaptable to changing crop and pest priorities, that can support the alignment of the management of farm trees with IPM. However, basic and applied biological and ecological research are needed to inform and validate these decision‐support tools and the capability to inform landscape‐scale models. Conceptual figure representing the three topics assessed in this review. Components include the crops, invertebrates, and trees and their arrangements. Interactions refer to the dynamic relationships between these components and management interventions. Opportunities include the measuring, promotion, better use of resources, research and demonstration and initiatives.

Exploitation of heterogenous distributions of Deroceras reticulatum, in arable fields by targeting molluscicide applications toward areas with higher slug densities, relies on these patches displaying sufficient spatio-temporal stability. Regular sampling of slug activity/distribution was undertaken using 1 ha rectangular grids of 100 refuge traps established in 22 commercial arable field crops. Activity varied significantly between the three years of the study, and the degree of aggregation (Taylor’s Power Law) was higher in fields with higher mean trap catches. Hot spot analysis detected statistically significant spatial clusters in all fields, and in 162 of the 167 individual assessment visits. The five assessment visits in which no clusters were detected coincided with low slug activity (≤0.07 per trap). Generalized Linear Models showed significant spatial stability of patches in 11 fields, with non-significant fields also characterized by low slug activity (≤1.2 per trap). Mantel’s permutation tests revealed a high degree of correlation between location of individual patches between sampling dates. It was concluded that patches of higher slug density were spatio-temporally stable, but detection using surface refuge traps (which rely on slug activity on the soil surface) was less reliable when adverse environmental conditions resulted in slugs retreating into the upper soil horizons.

Dispersal is a primary driver in shaping the future distribution of species in both terrestrial and marine systems. Physical transport by advection can regulate the distance travelled and rate of propagule supply to a habitat but post-settlement processes such as predation can decouple supply from recruitment. The effect of flow-mediated recruitment and predation on the recruitment success of an intertidal species, the eastern oyster Crassostrea virginica was evaluated in two-replicated field experiments. Two key crab species were manipulated to test predator identity effects on oyster mortality. Recruitment was ∼58% higher in high flow compared to low flow, but predation masked those differences. Predation mortality was primarily attributed to the blue crab Callinectes sapidus, whilst the mud crab Panopeus herbstii had no effect on recruit mortality. Recruit mortality from predation was high when recruit densities were high, but when recruit density was low, predation effects were not seen. Under high recruitment (supply), predation determined maximum population size and in low flow environments, recruitment success is likely determined by a combination of recruitment and resource limitation but not predation. Four processes are demonstrated: (1) Increases in flow rate positively affect recruitment success; (2) In high flow (recruitment) environments, resource availability is less important than predation; (3) predation is an important source of recruit mortality, but is dependent upon recruit density; and (4) recruitment and/or resource limitation is likely a major driver of population structure and functioning, modifying the interaction between predators and prey. Simultaneous testing of flow-mediated recruitment and predation was required to differentiate between the role of each process in determining population size. Our results reinforce the importance of propagule pressure, predation and post-settlement mortality as important determinants of population growth and persistence, but demonstrate that they should not be considered mutually exclusive.