How plant composition in margins influences the assemblage of pests and predators and its effect on biocontrol in melon fields.

Many agricultural landscapes offer few resources for maintaining natural enemy populations and floral plantings have frequently been adopted to enhance biological pest control in crops. However, restored margins may harbour both pests and natural enemies. The aim was to compare the abundance of pests and natural enemies in three types of margins (unmanaged, sown herbaceous floral strips and shrubby hedgerows) as well as in adjacent melon fields. Besides, yield was compared among melon fields as way of testing the effect of the type of margin on biocontrol. The research was carried out during 2 years in twelve melon fields from four different locations in southern Spain. Arthropods were sampled periodically in margins and melon fields by visual inspections and Berlese extraction. Hedgerow and floral strips hosted higher numbers of both pests and predators than unmanaged margins. Besides, hedgerows had a similar or higher number of natural enemies than floral strips but lower number of pests. In just a few occasions, the type of margin had a significant effect on the abundance of pests and natural enemies in melon fields, but rarely there was consistency between the two growing seasons. No differences were found in yield. We hypothesised that the lack of association in the abundances of pests and natural enemies between margins and melon fields could be attributed to the overriding effects of the landscape and/or the internal population dynamics of arthropods in melon fields. Overall, shrubby hedgerows are more recommended than herbaceous floral strips.

Stop me if you can: quantification of the effect of interfaces between plots on the dispersal of Cosmopolites sordidus.

BACKGROUND: Cosmopolites sordidus is one of the most damaging pests of banana worldwide. To date, most studies have addressed the control of this pest at the plot level, without considering the landscape scale, whereas between plots dispersion could be important. The aim of this study was to investigate the ability of C. sordidus to cross contrasted field interfaces. The 10 following interfaces were investigated: forests, hedgerows, field tracks, grassy areas, finely and coarsely tilled soil zones, ditches with and without water, vegetable gardening zones, and pheromone trap lines. Individually marked weevils were released on one side of the interface and recovered daily on the other side, allowing the estimation of the velocity and the crossing success of C. sordidus for each interface. RESULTS: Highest permeabilities (with a crossing success above 70%) were obtained for vegetable gardening zones, finely tilled soil zones, forests, and coarsely tilled soil zones. Intermediate permeabilities were measured for hedgerows, field tracks, grassy areas, and ditches without water. Only the line of pheromone traps and submerged ditches had a strong barrier effect on C. sordidus, with a crossing success below 12%. Wind strength, percentage of sky, and vegetation height were negatively correlated to the C. sordidus crossing success. CONCLUSION: Overall, our results showed that only ditches with water and lines of pheromone traps were efficient in stopping the dispersal of C. sordidus. The next step will be to conduct research to incorporate the use of these two interfaces at farm and landscape scale into integrated pest management strategies. © 2023 Society of Chemical Industry.

Not All Field Margins Are Equally Useful: Effects of the Vegetation Structure of Margins on Cereal Aphids and Their Natural Enemies.

Differences in the semi-natural vegetation of field margins will affect the biological control services derived from the presence of these semi-natural habitats adjacent to fields. Of the plant functional traits that are most relevant for insects, plant life forms reflect different aspects of plant structure and functioning that can help predict the value of marginal vegetation for arthropods in agricultural systems. The aim of this study was to determine the effect of the vegetation structure of field margins on cereal aphids and on some of their natural enemies (parasitoids, hoverflies and ladybugs) in terms of plant life forms. We characterized margin vegetation using the relative cover of each life form and sampled insects in crops along transects parallel to field margins. Our results show that in the studied areas, the abundance of natural enemies was greater near margins dominated by annual plants than in margins dominated by perennial plants. On the other hand, the abundances of aphids and parasitism rates were higher near margins dominated by perennial woody plants than near margins dominated by perennial herbaceous plants. By promoting specific life forms in existing margins, farmers can enhance the conservation biological control and relieve aphid pressure on their crops.

What drives bat activity at field boundaries?

Field boundaries are important habitat for bats in agricultural landscapes, serving as commuting and foraging areas for many species. The goal of our study was to better understand the drivers of bat activity in agricultural landscapes to inform conservation policy and make specific recommendations for habitat management. We placed sixty-four full spectrum bat detectors at random recording locations, weekly, along field boundaries in North Somerset between July and October 2020. We used an automated classifier to analyse recordings and performed error rate modelling to account for and remove the majority of error in automated classifications. We used generalised additive models to explore bat response to recording location metrics, controlling for spatial-autocorrelation and temporal differences in sampling. We validated our models with k-fold cross-validation and explored the utility of our models for predicting bat activity at new sites. We found that field boundary characteristics better describe bat activity than adjacent field characteristics or measures of local landscape for the majority of species studied. Bat activity was higher along tall, wide, vegetated field boundaries containing trees; there was lower activity at arable recording locations. Still, bat activity was highly variable and predictive error was high. We found a large spatial effect driving activity patterns, meaning models are not able to predict activity beyond the extent of the study area. We recommend management strategies that give incentives to farmers for replacing fences with hedgerows, planting hedgerow trees, and maintaining tall and outgrown field boundaries.

Pesticide exposure of wild bees and honey bees foraging from field border flowers in intensively managed agriculture areas.

Bees are critical for food crop pollination, yet their populations are declining as agricultural practices intensify. Pollinator-attractive field border plantings (e.g. hedgerows and forb strips) can increase bee diversity and abundance in agricultural areas; however, recent studies suggest these plants may contain pesticides. Pesticide exposure for wild bees remains largely unknown; however, this information is needed to inform agricultural practices and pesticide regulations meant to protect bees. It is important to determine whether border plantings that attract and support pollinators may also deliver pesticides to them. In this study, we collected various samples for pesticide residue analysis, including: multiple species of wild bees, honey bees, flowers from four types of bee-attractive field border plants, and soil. Silicone bands were also utilized as passive aerial samplers of pesticide residues. The five pesticides detected most frequently across all samples were the insecticide bifenthrin, the herbicides thiobencarb, metolaclor, and propanil, and the fungicide fluopyram. We detected the greatest number of parent pesticides in bands (24), followed by soil (21). Pesticides were also detected in field border plant flowers (16), which do not receive direct pesticide applications, and included many products which were not applied to adjacent field crops. Pesticide concentrations were lower in bees than in flowers but higher in bees than in soils. Pesticide residue per bee (ng/bee) increased with increasing wild bee size, though pesticide concentration (ng/g) did not increase. While honey bees and wild bees contained a similar number and concentration of pesticides overall, pesticide mixtures varied by bee type, and included some mixtures known to cause sublethal effects. The results from this study highlight the benefits of measuring more sample types to capture the total exposome of bees, including a greater range of bee species, as well as the need to consider exposure to pesticides at the landscape level.

Different effects of warming treatments in forests versus hedgerows on the understorey plant Geum urbanum.

The effectiveness of hedgerows as functional corridors in the face of climate warming has been little researched. Here we investigated the effects of warming temperatures on plant performance and population growth of Geum urbanum in forests versus hedgerows in two European temperate regions. Adult individuals were transplanted in three forest-hedgerow pairs in each of two different latitudes, and an experimental warming treatment using open-top chambers was used in a full factorial design. Plant performance was analysed using mixed models and population performance was analysed using Integral Projection Models and elasticity analyses. Temperature increases due to open-top chamber installation were higher in forests than in hedgerows. In forests, the warming treatment had a significant negative effect on the population growth rate of G. urbanum. In contrast, no significant effect of the warming treatment on population dynamics was detected in hedgerows. Overall, the highest population growth rates were found in the forest control sites, which was driven by a higher fecundity rather than a higher survival probability. Effects of warming treatments on G. urbanum population growth rates differed between forests and hedgerows. In forests, warming treatments negatively affected population growth, but not in hedgerows. This could be a consequence of the overall lower warming achieved in hedgerows. We conclude that maintenance of cooler forest microclimates coul, at least temporarily, moderate the species response to climate warming.

The use of hedgerows to mitigate pesticide exposure of a population living in a rural area.

Farmer populations living in houses inside vegetable gardens are exposed to indoor pesticide pollution. The pulverization drift and volatile pesticides transported by wind are important sources of indoor pollution, which can be mitigated by hedgerows. This study was the first attempt in Brazil to investigate the efficiency of six different hedgerow species in reducing pesticide residues in air. A fluorescent compound (p-aminobenzoic acid or PABA) was introduced in the sprayed pesticide fluid that traced the pesticide in the water. Samples were collected in Petri dishes positioned on stakes at different heights in front of and behind the hedgerows. Data indicated barrier efficiency of up to 99%. Simulation of nontarget drift contamination with herbicide concentrations exhibited reduced senescence effects on leaves and posed no threat to survival. Hedgerows are feasible, simple, and inexpensive techniques, which may be used easily by farmers, independent of external support and efficiently mitigating indoor pesticide pollution, thus protecting human health. Integr Environ Assess Manag 2022;18:19-24. © 2021 SETAC.

Classification of Mediterranean hedgerows: A methodological approximation.

The present paper addresses the methodology carried out to obtain a new classification of hedgerow networks in the Mediterranean region using GIS and Remote Sensing. A new methodology has been developed due to the need to establish a typification of the hedgerows in this sector of southern Europe, where the variable conditioning the localization, area and type of these landscapes is degree of surface soil moisture. In the continental Mediterranean context, this age-old agricultural system is closely linked to access to, and management of, water resources, which are vital in the dry season. For this reason, we mapped the hedgerow network of a continental Mediterranean mountain, establishing different levels of surface soil moisture provided by images from the satellite Sentinel-2. The results render three types of hedgerows: moist, semi-moist and dry, each one presenting clearly differentiated localizations and characteristics. To this can be added the analysis of the evolution of their area from 1956 to the present time from aerial pictures and satellite images and their correlation with surface soil moisture and slope. We present results on this tested method from the central sector of the Iberian Peninsula, Spain.•The presented procedure focuses on a new classification of hedgerow networks in the Mediterranean region based on the degree of surface soil moisture.•The method stablishes different levels of surface soil moisture provided by images from the satellite Sentinel-2.•The procedure allows us to analyze and correlate the evolution of Mediterranean hedgerows with surface soil moisture.

Emerging helminthiases of song thrush (Turdus philomelos) in Central Europe.

Turdus philomelos is a common Western Palearctic thrush species of forests and agricultural landscapes, where it relies on the presence of hedgerows, patches of trees, and shrubs. In the present study, we address long-term changes in component communities of trematodes in T. philomelos across the timespan of over half a century. Based on our preliminary observations, we hypothesized that component communities of trematodes in T. philomelos in the study area are more diverse and species-rich compared with several decades ago. In the 1961-2019, we performed full-body necropsies of T. philomelos, which originated from the southern Czech Republic, and examined them for the presence of trematodes. We compared the trematode species richness and diversity of the analyzed component communities. The number of trematode species per host steadily increased in time in adult females and males. In juveniles, the highest numbers of trematode species per host were reached already in 1961-1990, then dropped and slowly raised up again in the latter time periods. The newly accumulated evidence suggests that trematodes with intermediate hosts previously restricted to T. philomelos wintering grounds increased in abundance in the study area. Some of them (Morishitium polonicum, Psilotornus confertus) sporadically appeared in juveniles or first-year birds, from which they were previously completely absent. Some of the spreading species, such as Lutztrema attenuatum, are present in high prevalence and high intensities of infection. Yet unknown part of observed changes could be related to changes in food composition; however, direct evidence for changes in T. philomelos diet is lacking despite clear evidence for a decline in earthworms in agricultural landscapes.

Flowering plant composition shapes pathogen infection intensity and reproduction in bumble bee colonies.

Pathogens pose significant threats to pollinator health and food security. Pollinators can transmit diseases during foraging, but the consequences of plant species composition for infection is unknown. In agroecosystems, flowering strips or hedgerows are often used to augment pollinator habitat. We used canola as a focal crop in tents and manipulated flowering strip composition using plant species we had previously shown to result in higher or lower bee infection in short-term trials. We also manipulated initial colony infection to assess impacts on foraging behavior. Flowering strips using high-infection plant species nearly doubled bumble bee colony infection intensity compared to low-infection plant species, with intermediate infection in canola-only tents. Both infection treatment and flowering strips reduced visits to canola, but we saw no evidence that infection treatment shifted foraging preferences. Although high-infection flowering strips increased colony infection intensity, colony reproduction was improved with any flowering strips compared to canola alone. Effects of flowering strips on colony reproduction were explained by nectar availability, but effects of flowering strips on infection intensity were not. Thus, flowering strips benefited colony reproduction by adding floral resources, but certain plant species also come with a risk of increased pathogen infection intensity.

Assessing common birds' ecological requirements to address nature conservation in permanent crops: Lessons from Italian vineyards.

Viticulture has contributed to shaping cultural landscapes in several regions across all continents. Recent farming intensification is causing landscape homogenization and biodiversity loss in several of those areas, but knowledge about the impacts on biodiversity in vineyards is still scarce. Simplified agro-ecosystems resulting from intensification host mainly generalist and common species, which still play a key role in the regulation of ecosystems and in the provision of ecosystem services. We assessed the abundance of 11 common bird species at 47 linear transects in a vineyard-dominated landscape in Trentino (NE Italy), in both spring and winter, and analysed abundance variation in relation to three independent groups of predictors: landscape, management, and topographic-climatic variables. In the majority of species (7), abundance was primarily or considerably affected by landscape attributes. However, an additional 5 species were largely affected by management practices, often with conspicuous seasonal differences. Overall, landscape and management heterogeneity positively affected the abundance of 6 species. Vineyard cover (and in particular the new spalliera trellising system) was negatively related with the abundance of 6 species, with the strongest impacts occurring in winter. On the contrary, the cover of marginal habitats had major positive effects over 8 species. Hedgerows, tree rows, and dry stone walls, as well as traditional pergola vineyards and landscape and management heterogeneity should be conserved or restored in viticultural landscapes to promote the abundance of common bird species. This strategy would ensure the maintenance of the ecosystem services they provide, while promoting the general sustainability of the agroecosystem.

Cultivar and Tree Density As Key Factors in the Long-Term Performance of Super High-Density Olive Orchards.

Super high-density (SHD) olive orchards are rapidly expanding since the first plantation was set up in Spain in the 1990s. Because there are no long-term studies characterizing these systems, it is unknown if densities above a certain threshold could trigger competition among fully-grown trees, compromising their development. Over 14 years we have evaluated the performance of the major olive cultivars currently planted in SHD systems ("Arbequina," Arbequina IRTA-i·18, "Arbosana," "Fs-17," and "Koroneiki") and nine SHD designs ranging from 780 to 2254 trees ha(-1) for the cultivar "Arbequina." Remarkably, the accumulated fruit and oil production of the five cultivars increased linearly over time. Our data indicated the favorable long-term performance of the evaluated cultivars with an average annual oil production of 2.3 t ha(-1). Only "Fs-17" did not perform well to the SHD system in our conditions and it yielded about half (1.2 t ha(-1)) of the other cultivars. In the density trial for "Arbequina," both fruit and oil accumulated production increased over time as a function of tree density. Thus, the accumulated oil yield ranged from 16.1 t ha(-1) for the lowest density (780 trees ha(-1)) to 29.9 t ha(-1) for the highest (2254 trees ha(-1)). In addition, we note that the accumulated production per surface unit showed a better correlation with the hedgerow length than the tree density. Thus, the current planting designs of SHD olive orchards can be further improved taking this parameter into account. Despite observations that some irregular patterns of crop distribution have arisen, our olive hedgerows are still fully productive after 14 years of planting. This result contradicts previous experiences that showed declines in production 7 or 8 years after planting due to high vigor, shading, and limited ventilation.

Changes in bird populations on sample lowland English farms in relation to loss of hedgerows and other non-crop habitats.

Farmland bird population trends were examined on a sample of lowland English farms to assess the relative importance of habitat loss and habitat degradation. Data were extracted from 11 farms surveyed by territory mapping between 1966 and 1986 as part of the British Trust for Ornithology's Common Birds Census. The population size of 38 bird species was quantified for each farm in each year. The extents of five non-crop habitats were measured at 4-yearly intervals on each farm. The farms were selected because some had undergone extensive removal of non-crop habitats while others had undergone little or none. Although declines were commonest on farms where the severest habitat loss had taken place, we found no evidence that habitat loss was the main factor causing population declines: all 11 farms had significant numbers of declining species, even where habitat loss was minimal. Furthermore, general linear modelling found no significant effects of habitat loss on population trends and principal-components analysis found limited effects of habitat extent on community composition. These results suggest that habitat loss is of secondary importance in causing farmland bird population declines. We suggest that other processes, such as habitat degradation, may have caused a baseline population decline in at least 10 farmland bird species and that declines may have been exacerbated by localised habitat loss.