Non-crop Habitats Research Articles

Artificial temporary non-crop habitats support parasitoids on arable land

Non-crop habitats are important to support biodiversity and ecosystem services in agricultural landscapes. Whereas perennial and managed non-crop habitats have known benefits, temporary non-crop patches within arable fields (field defects) have been poorly studied. We created artificial field defects (unsown patches) in oilseed rape (Brassica napus L.) fields and evaluated their effects on parasitoid assemblages at two crop growth stages. Moreover, we compared unmanaged patches with those sown with flowering plants (Onobrychis vicifolia) and crop controls and analyzed the influence of position within the field (edge or interior), and total flower availability. Altogether, we found almost 200 morphospecies of hymenopteran parasitoids (140 in unsown patches, 147 in Onobrychis patches, and 81 in controls), including important enemies of crop pests. Species richness and abundance were higher on both types of unsown patches than in controls but were not affected by Onobrychis sowing. The differences between unsown patches and controls were larger during oilseed ripening, suggesting that these temporary habitats can offer important resources during crop senescence. Parasitoid species composition differed between controls and unsown patches, indicating that species not linked to the crop could also benefit from these habitats. Finally, unsown patches with higher flower availability supported higher species richness, total abundance, and abundance of three key species during OSR flowering. Thus, newly created unmanaged habitats have the potential to increase biodiversity despite their small size, although increasing flower resources can boost their benefits. Unsown patches can be easily created by switching-off sowing, facilitating their adoption by farmers. Future studies on pest control levels and comparisons with other agri-enviromental schemes would help to elucidate the cost-benefit of unsown patches.

Farmland biodiversity: wildflower-sown islands within arable fields and grassy field margins both promote spider diversity

Agricultural intensification and the concomitant landscape homogenization is leading to a worldwide decline in farmland biodiversity. Non-crop habitats in agroecosystems may counteract the loss of arthropods such as spiders and thus contribute to sustainable agriculture. However, the effectiveness of field margins and set-aside wildflower-sown patches in maintaining spider diversity is not well understood. Here, we investigated the effects of three different non-crop habitats, namely field margins, set-aside wildflower-sown patches under power poles (‘power pole islands’), and grassland fallows on spider diversity as compared to wheat fields in an agricultural landscape in western Germany. Using pitfall trapping and suction sampling, we show that species richness and overall conservation value were higher in non-crop habitats than in wheat fields. Interestingly, field margins and power pole islands differed from long-term grassland fallows only in conservation value, which was significantly higher in grassland fallows. Species assemblages differed considerably between grassland fallows, field margins and power pole islands, and wheat fields, documenting the added value of using different conservation strategies.Implications for insect conservationSmall-scale non-crop habitats adjacent to wheat fields were surprisingly effective in promoting spider diversity in an agricultural landscape, with field margins and power pole islands being equally effective. To maximize overall diversity in agricultural landscapes, we propose a combination of larger long-term fallows and smaller non-crop habitats such as field margins or set-aside wildflower-sown patches.

Establishment and management of wildflower areas for insect pollinators in commercial orchards

Sown wildflower areas are increasingly recommended as an agri-environmental intervention measure, but evidence for their success is limited to particular insect groups or hampered by the challenges of establishing seed mixes and maintaining flower abundance over time. We conducted a replicated experiment to establish wildflower areas to support insect pollinators in apple orchards. Over three years, and across 23 commercial UK orchards with and without sown wildflowers, we conducted 828 transect surveys across various non-crop habitats. We found that the abundance of flower-visiting solitary bees, bumblebees, honeybees, and beetles was increased in sown wildflower areas, compared with existing non-crop habitats in control orchards, from the second year following floral establishment. Abundance of hoverflies and other non-syrphid flies was increased in wildflower areas from the first year. Beyond the effect of wildflower areas, solitary bee abundance was also positively related to levels of floral cover in other local habitats within orchards, but neither local nor wider landscape-scale context affected abundance of other studied insect taxa within study orchards. There was a change in plant community composition on the sown wildflower areas between years, and in patterns of flowering within and between years, showing a succession from unsown weedy species towards a dominance of sown species over time. We discuss how the successful establishment of sown wildflower areas and delivery of benefits for different insect taxa relies on appropriate and reactive management practices as a key component of any such agri-environment scheme.

Mass-flowering monoculture attracts bees, amplifying parasite prevalence.

As the global agricultural footprint expands, it is increasingly important to address the link between the resource pulses characteristic of monoculture farming and wildlife epidemiology. To understand how mass-flowering crops impact host communities and subsequently amplify or dilute parasitism, we surveyed wild and managed bees in a monoculture landscape with varying degrees of floral diversification. We screened 1509 bees from 16 genera in sunflower fields and in non-crop flowering habitat across 200 km2 of the California Central Valley. We found that mass-flowering crops increase bee abundance. Wild bee abundance was subsequently associated with higher parasite presence, but only in sites with a low abundance of non-crop flowers. Bee traits related to higher dispersal ability (body size) and diet breadth (pollen lecty) were also positively related to parasite presence. Our results highlight the importance of non-crop flowering habitat for supporting bee communities. We suggest monoculture alone cannot support healthy bees.

Characterizing the Spatiotemporal Distribution of Three Native Stink Bugs (Hemiptera: Pentatomidae) across an Agricultural Landscape.

Simple SummaryStink bugs (Hemiptera: Pentatomidae) are highly mobile pests that forage on, and damage, a variety of crops. Habitats that surround farms, such as forests, wetlands, and pastures may play a role in the location of stink bugs and their movement into crop fields. Here, stink bugs were trapped weekly across an 18 km2 agricultural landscape, and we characterized their distribution, as well as patterns of aggregation by habitat. Brown stink bugs (Euschistus servus) were most often captured in crop fields and the timing of aggregations often corresponded to food availability. Dusky stink bugs (Euschistus tristigmus) were primarily captured in forest, and only occasionally in crop fields. Green stink bugs (Chinavia hilaris) were found in both crop fields and non-crop habitat. Control of stink bugs may require management plans that consider movement not only within crop fields, but also the surrounding habitat.Stink bugs (Hemiptera: Pentatomidae) are polyphagous pests that cause significant economic losses to a variety of crops. Although many species have been documented to aggregate within agricultural fields, much less is known regarding the timing and distribution of adults and nymphs within and between surrounding non-crop habitat. Therefore, we explored the spatiotemporal distribution of Euschistus servus (Say), Euschistus tristigmus (Say), and Chinavia hilaris (Say), three species of North American origin, and examined whether distribution patterns varied between species according to habitat. Stink bugs were monitored weekly for three years within an 18 km2 grid of pheromone-baited traps. We tested whether habitat affected distribution patterns, used spatial analysis by distance indices (SADIE) to identify aggregations, and visualized distributions with interpolated maps. Overall, E. servus adults were captured in crops, whereas E. tristigmus adults and nymphs were mainly captured in forests. Accordingly, distribution patterns of E. tristigmus were relatively stable over time, whereas aggregations of adult E. servus varied over space, and the timing of aggregations reflected the phenology of major crops. Chinavia hilaris was most often captured in forest, followed by crop habitat. Pest management strategies for stink bugs may require an area-based management approach that accounts for movement in agricultural fields and surrounding habitat.

Biodiversity in agricultural landscapes: different non-crop habitats increase diversity of ground-dwelling beetles (Coleoptera) but support different communities

Agricultural intensification poses a major threat to the conservation of biodiversity and associated ecosystem services. Since non-crop habitats are regarded as important refuges for farmland biodiversity, various greening measures have been proposed to halt biodiversity loss. However, the effectiveness of these measures for biodiversity conservation is still under debate. Therefore, we here compared ground-dwelling beetle (Coleoptera) assemblages of different non-crop habitats (field margins, set-aside fields sown with wildflowers, and permanent grassland fallows) and wheat fields within an intensively used agricultural landscape in western Germany. Taxonomic diversity of Carabidae, Staphylinidae and other coleopteran families and their conservation value were higher in all non-crop habitats than on wheat fields. Surprisingly, though, different types of non-crop habitats did not differ in species richness or the number of threatened species. Thus, field margins and sown wildflower fields were as effective in promoting beetle diversity as grassland fallows. However, different non-crop habitats supported different species assemblages, and several species, in particular especially large ones, were restricted to grassland fallows. These results suggest that different greening measures are effective in promoting the biodiversity of beetles, and that permanent grassland fallows are essential for nature conservation. The fact that habitat types harbored different assemblages stresses the need to combine a variety of greening measures to yield the highest benefit for biodiversity.

'Candidatus Liberibacter solanacearum' Infection of Physalis ixocarpa Brot. (Solanales: Solanaceae) in Saltillo, Mexico.

The potato psyllid Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is a pest of solanaceous crops (order Solanales), including potato (Solanum tuberosum L.) and tomato (S. lycopersicum L.). Feeding by high populations of nymphs causes psyllid yellows while adults and nymphs are vectors of the plant pathogen 'Candidatus Liberibacter solanacearum'. Foliar symptoms that were consistent with either 'Ca. L. solanacearum' infection or psyllid yellows were observed in 2019 on tomatillo (Physalis ixocarpa Brot.; family Solanaceae) grown within an experimental plot located near Saltillo, Mexico. This study had three primary objectives: 9i) determine whether the foliar symptoms observed on tomatillo were associated with 'Ca. L. solanacearum' infection, (ii) identify the haplotypes of 'Ca. L. solanacearum' and potato psyllids present in the symptomatic plot, and (iii) use gut content analysis to infer the plant sources of 'Ca. L. solanacearum'-infected psyllids. Results confirmed that 71% of symptomatic plants and 71% of psyllids collected from the plants were infected with 'Ca. L. solanacearum'. The detection of 'Ca. L. solanacearum' in plants and psyllids and the lack of nymphal populations associated with psyllid yellows strongly suggests that the observed foliar symptoms were caused by 'Ca. L. solanacearum' infection. All infected plants and insects harbored the more virulent 'Ca. L. solanacearum' haplotype B but one psyllid was also coinfected with haplotype A. The potato psyllids were predominantly of the central haplotype but one psyllid was identified as the western haplotype. Molecular gut content analysis of psyllids confirmed the movement of psyllids between noncrop habitats and tomatillo and indicated that 'Ca. L. solanacearum' infection of psyllids was associated with increased plant diversity in their diet.

Conservation of Non-Pest Whiteflies and Natural Enemies of the Cabbage Whitefly Aleyrodes proletella on Perennial Plants for Use in Non-Crop Habitats

Simple SummaryThe cabbage whitefly Aleyrodes proletella is a major insect pest of many cabbage crops. Natural enemies, in particular Encarsia tricolor as well as different hoverfly larvae and spiders, do not decrease pest populations sufficiently. The objective of this study is to promote local natural enemy populations by permanently establishing a non-pest whitefly species, which is an alternative host and additional food source when A. proletella is scarce or even absent. Therefore, the perennial abundance of the non-pest honeysuckle whitefly Aleyrodes lonicerae and natural enemies on different plants were evaluated in the open field. Wood avens Geum urbanum was the best host plant for A. lonicerae in terms of reproduction and overwintering. Most E. tricolor and spiders were also found on this plant species. In the future, G. urbanum might be used in non-crop habitats to increase natural enemy abundances in the agricultural landscape and decrease damage caused by A. proletella on adjacent cabbage plants.Aleyrodes proletella causes severe economic damage to several Brassica crops. Its naturally occurring enemies often immigrate late in the season or appear in low numbers on cabbage. This field study aims to permanently increase the local abundance of A. proletella’s natural enemies by providing the non-pest whitefly Aleyrodes lonicerae as an alternative and overwintering host/prey. Therefore, the population dynamics of natural enemies on different perennial herbaceous plants pre-infested with A. lonicerae were determined at two field locations over two winter periods. Most A. lonicerae colonized (on average 166.22 puparia per m²) and overwintered (342.19 adults per m²) on wood avens Geum urbanum. Furthermore, the abundance of A. proletella main parasitoid Encarsia tricolor (28.50 parasitized puparia per m²) and spiders (12.13 per m²) was 3–74 times and 3–14 times higher, respectively, on G. urbanum compared to the other experimental plants. Conclusively, G. urbanum pre-infested with A. lonicerae permanently promoted natural enemies of A. proletella by serving as shelter, reproduction, and overwintering habitat. A potential implementation of G. urbanum in conservation biological control strategies (e.g., tailored flower strips, hedgerows) against A. proletella are discussed and suggestions for future research are given.

Reduced diversity of farmland birds in homogenized agricultural landscape: A cross-border comparison over the former Iron Curtain

Agricultural intensification led to a transformation of structurally complex agricultural landscapes that resulted in a subsequent loss of landscape heterogeneity. Landscape homogenization is considered a crucial process which influences farmland biodiversity; however, separating the effects of homogenization from other environmental gradients is difficult and rarely tested. This study aimed to compare farmland bird communities in two cross-border regions (Austria and the Czech Republic) across the former Iron Curtain that have a similar share of arable land and non-crop habitats, but markedly differ in landscape homogenization. Due to historical differences in political and socio-economic systems, the farmland in Austria is dominated by small-scale farming, whereas large-scale farming is characteristic of the Czech Republic. Using two independent datasets (i.e., point-counts and transect-counts), we found substantially (ca. 1.5-fold) higher abundance and species richness of farmland birds in Austria compared to the Czech Republic. Most of the farmland bird species (although not all) were significantly more abundant in Austria in comparison to the Czech Republic and none showed a reversed pattern. A positive association between landscape heterogeneity and farmland bird diversity suggests that conservation measures promoting small and fragmented crop fields over large ones and increasing field margins may be an effective measure to increase declining farmland biodiversity. Financial support for the agricultural production of small-scale farming agroecosystems may be an option.

Detection of Fruit Meals Within Laboratory-Raised and Field-Trapped Adult Drosophila suzukii (Diptera: Drosophilidae) Guts

The feeding habits of adult Brachycera are understudied and may provide important context for understanding invasive pest biology, as with the polyphagous small fruit pestDrosophila suzukii. We developed molecular methods to study adultD. suzukiigut content in order to understand its feeding habits. We designed and verified two primer pairs specific for either blueberries or blackberries and used a qPCR melt curve analysis to determine whether we can detect the presence or absence of berry feeding by adult flies. In a laboratory assay, the blueberry fly meal DNA can be detected for longer periods than the blackberry meal DNA. Generally, female gut contents are less variable than male gut contents. We also tested recently emerged flies that were not fed as adults but developed as larvae in either blueberries or blackberries. Some adult flies from each fruit had detectable fruit DNA in their gut, which could be due to pupal meconium feeding after emergence. Next, we aimed to test the primers in the field to develop techniques to track fruit feeding byD. suzukiiin its natural field environment. First, to identify the most appropriate collection method, we determined how long we could detect fruit DNA, using previously developed primers withinD. suzukiigut preserved in four types of trap fluid in the laboratory. The likelihood of detecting blackberry DNA differed by day, trap fluid, and between sexes. For the blueberry primer, the possibility of detecting blueberry DNA differed by trap fluid only. Based on those results, we used RV antifreeze with a Scentry SWD lure in field trials at two research station locations, one containing blackberries and one with blueberries. We established transects away from each fruit planting and collected up to 120 total flies at each point along transects. There were no significant differences in the number of flies containing berry DNA among collection points along the transect in both locations. These results suggest that adult flies move between crop and non-crop habitats and may not be highly dependent on fruit food resources.

Species diversity and food web structure jointly shape natural biological control in agricultural landscapes

Land-use change and agricultural intensification concurrently impact natural enemy (e.g., parasitoid) communities and their associated ecosystem services (ESs), i.e., biological pest control. However, the extent to which (on-farm) parasitoid diversity and food webs mediate landscape-level influences on biological control remains poorly understood. Here, drawing upon a 3-year study of quantitative parasitoid-hyperparasitoid trophic networks from 25 different agro-landscapes, we assess the cascading effects of landscape composition, species diversity and trophic network structure on ecosystem functionality (i.e., parasitism, hyperparasitism). Path analysis further reveals cascaded effects leading to biological control of a resident crop pest, i.e., Aphis gossypii. Functionality is dictated by (hyper)parasitoid diversity, with its effects modulated by food web generality and vulnerability. Non-crop habitat cover directly benefits biological control, whereas secondary crop cover indirectly lowers hyperparasitism. Our work underscores a need to simultaneously account for on-farm biodiversity and trophic interactions when investigating ESs within dynamic agro-landscapes.

Regenerative Almond Production Systems Improve Soil Health, Biodiversity, and Profit

Regenerative agriculture aims to improve soil health and promote biodiversity while producing nutritious food profitably. Almonds are the dominant crop in California agriculture in terms of acreage and revenue generated. We examined the soil health, biodiversity, yield, and profit of regenerative and conventional almond production systems that represented farmer-derived best management practices. Regenerative practices included abandoning some or all synthetic agrichemicals, planting perennial ground covers, integrating livestock, maintaining non-crop habitat, and using composts and compost teas. Total soil carbon (TSC), soil organic matter (SOM), total soil nitrogen (TSN), total soil phosphorous, calcium, sulfur, and soil health test scores were all significantly greater in regenerative soils. Water infiltrated regenerative soils six-fold faster than conventional soils. Total microbial biomass, total bacterial biomass, Gram+ bacteria, and Actinobacteria were significantly greater in regenerative soils. There was more plant biomass, species diversity, and percent cover in regenerative orchards. Invertebrate richness and diversity, and earthworm abundance and biomass were significantly greater in regenerative orchards. Pest populations, yields, and nutrient density of the almonds were similar in the two systems. Profit was twice as high in the regenerative orchards relative to their conventional counterparts. No one practice was responsible for the success of regenerative farms; their success was the result of simultaneously combining multiple regenerative practices into a single, functional farm system. This style of farming may assist in combatting planetary scale problems (e.g., climate change, biodiversity loss, agricultural pollution, chronic human health problems, and declining rural communities) while making farms more profitable and resilient.

Non-crop sources of beneficial arthropods vary within-season across a prairie agroecosystem

Ground-dwelling arthropods can be important generalist predators in agroecosystems, and can use non-crop features as overwintering habitats. However, it is unclear which types of landscape features constitute useful non-crop habitat, and at what spatial scale organisms gather resources. Additionally, the same landscape feature may act as a source or a destination for arthropods at different times of the year, but this is rarely considered. We modeled the abundance of four common species of Canadian prairie arthropods caught in a set of 198 in-field and roadside pitfall traps (June to August of 2017). Functional regression was used in order to simultaneously consider both the habitat preferences and the timing of movement from the land cover classes. Pterostichus melanarius (Coleoptera: Carabidae) and Pardosa moesta (Araneae: Lycosidae) were attracted to canola (Brassica napus) during the early summer, then dispersed to grasslands, wetlands, and grassy road margins at the end of the summer. In particular, Pterostichus melanarius aggregated in canola early in the growing season, suggesting that its role in suppressing crop pests may be underestimated. Pardosa distincta (Araneae: Lycosidae) and Phalangium opilio (Opiliones: Opilionidae) showed weak patterns of seasonal migration, and were more influenced by large-scale geographic patterns rather than landscape composition. Our results suggest that predatory arthropods may migrate into canola crops during the early summer, and that grasslands and wetlands may act as seasonal reservoir habitats. Farmers and land managers should consider preserving existing habitat in order to maintain pest-control services across the season.

Soil Arthropods in the Douro Demarcated Region Vineyards: General Characteristics and Ecosystem Services Provided

Viticulture is one of the oldest and most profitable forms of agriculture; it is also one of the most intensive farming systems. As intensive cultivation threatens the environment, there is increasing interest in the concept of sustainability within the wine industry, as well as new business opportunities, as customers begin to pay more attention to environmental and sustainability issues. Recognizing the key role of soil quality in environmentally and economically sustainable viticulture makes it essential to understand better soil arthropod communities, given their crucial functions in maintaining soil quality and health. The ‘Douro Demarcated Region’ (DDR) in northern Portugal offers good potential, in regards to biodiversity, due to its significant areas of non-crop habitats. This work aims to compile information on soil arthropod communities (both soil surface and soil-living) collected in the DDR vineyard agroecosystems. A description of the ecosystem services provided by them, as a basis for the development and implementation of sustainable viticulture systems, is also an objective of this work. An important set of soil arthropods necessary for the delivery of vital ecosystem services for viticulture, with particular reference to supporting and regulating services, occurred in this ecosystem. Eight classes were chiefly represented in a sample of about 167,000 arthropod specimens: Arachnida, Chilopoda, Diplopoda, Entognatha, Insecta, Malacostraca, Pauropoda, and Symphyla. The most representative were Entognatha and Insecta in soil-surface arthropods, and Arachnida and Entognatha in soil-living arthropods. The presence of recognized groups as bioindicators in agroecosystems, such as soil quality indicators, is also revealed. This knowledge is expected to contribute to a more efficient and sustainable management of the viticultural ecosystem.

Dynamics of montane vole (Microtus montanus) populations in set-asides, field margins, and orchards: Keystone or pest species?

Voles of the genus Microtus are major small mammal species responsible for feeding damage to agricultural crops in Europe and North America. Microtus also occupy non-crop habitats such as field margins, hedgerows, edges, riparian zones, set-asides, and fallow fields where the conundrum of “keystone species” vs. “pest species” arises. We ask if montane vole (M. montanus) populations will occupy small set-asides and potentially move into field margins adjacent to tree fruit orchards during periods of high numbers? In replicated sites in south-central British Columbia, Canada, in 2009–2012, we tested the hypotheses (H) that (H1) small (0.25 ha) perennial grassland sites would be high-quality habitat for voles and generate a multi-annual population fluctuation in abundance; (H2) voles will follow the same population pattern in set-asides and field margins; and (H3) voles occurring in set-aside and field margins will disperse into adjacent tree fruit orchards. In set-asides, voles increased to a mean peak population of 290 voles/ha and then declined to 50/ha thereby providing support for H1. Montane voles generally followed the same pattern of population changes in set-asides and field margins thereby supporting H2. A much reduced abundance of voles in field margins was likely owing primarily to the areal versus linear extent of the two habitats as both had similar mean abundance of herbs, thatch, and structural diversity. Vegetation management in orchards contributed to very low numbers of voles, and hence no relationship in population pattern with the set-asides. Movement of voles from set-asides to field margins was low and from set-asides and field margins to orchards was almost negligible, thereby providing no support for H3. There was no feeding damage to crop production during winter periods. Conservation of even small (0.25 ha) set-asides of perennial grasslands may provide high-quality habitat for fluctuating populations of montane voles without necessarily impacting crop production in adjacent orchards that have appropriate vegetation management. Microtus species may be considered keystone architects of biodiversity in at least some agricultural contexts.

Land use alters the abundance of herbivore and predatory insects on crops: the case of alfalfa

We assess the effects of changing land use and crop management on alfalfa insect abundance by comparing it in 50 alfalfa fields when they were inserted in landscapes with different proportions of arable crops and orchards. Land use in a buffer of 500 m was assessed, and alfalfa insect abundance was estimated with sticky yellow traps. The number of catches of several herbivores and predators was related to the proportion of landscape components and several field variables. Results indicated that the proportion of orchards in the buffer negatively affected the abundance of predators on alfalfa, likely because orchards treated with pesticides are a sink for predators moving in the landscape, among other possible causes. Other landscape variables such as noncrop habitats, winter cereals, and landscape diversity analysed by the Shannon index had a minor influence. Among field variables, field size influenced positively the abundance of insects on alfalfa, whereas alfalfa growth stage and age affected positively or negatively the different herbivores and predators. Of course, abundance of predators and prey was affected by the abundance of prey and predators, respectively. These findings suggest that a high proportion of intensively managed crops (orchards) in the landscape interferes with the role of alfalfa as a reservoir of predatory insects for adjacent crops and that the responses to local and landscape structures are temporal and species-specific as previously concluded for maize. Consequently, landscape and field management strategies to improve pest control must consider both types of variables as well as their changing influence when we modify them.

Spatiotemporal Distribution of Stink Bugs (Hemiptera: Pentatomidae) in Peach Orchards and Surrounding Habitat

Stink bugs (Hemiptera: Pentatomidae) are economic pests of a variety of fruit crops across the southeastern USA, and damage by stink bugs to peaches is common. The landscape surrounding orchards may influence stink bug distribution and dispersal into this commodity, but such patterns may vary over the growing season. Accordingly, stink bug control should be targeted seasonally towards habitats that effectively reduce or prevent damage to peach. In this study, we used pheromone-baited traps to characterize distribution patterns of 2 stink bug species, Euschistus servus (Say) and Euschistus tristigmus (Say) (both Hemiptera: Pentatomidae), in peach orchards and surrounding habitat over 2 seasons at 3 sites in central Georgia, USA. In addition, we used Spatial Analysis by Distance Indices to identify significant aggregations of each species over the duration of the growing seasons. Adults captured in traps differed by species, and distribution patterns varied by habitat and wk sampled. Euschistus servus was commonly found in peaches, whereas E. tristigmus was not. Regardless of orchard or yr, adult E. servus tended to avoid woodland habitat, whereas E. tristigmus tended to prefer this habitat type. Both species increased later in the season in peach orchards with significant spatial aggregations of each detected at all orchards. However, the wk in which aggregations were detected varied by orchard and yr. Across all orchards, E. servus adults clustered mainly in peach trees adjacent to pecan, as well as pine, fallow, and kudzu habitat. Adult E. tristigmus aggregated primarily in woodland, pine, and pecan habitat. Seasonal distribution patterns of E. servus and E. tristigmus suggest that control measures may need to be implemented on a fine spatial scale across peach and non-crop habitats.

Landscape complexity promotes resilience of biological pest control to climate change.

Increased climate variability as a result of anthropogenic climate change can threaten the functioning of ecosystem services. However, diverse responses to climate change among species (response diversity) can provide ecosystems with resilience to this growing threat. Measuring and managing response diversity and resilience to global change are key ecological challenges. Here, we develop a novel index of climate resilience of ecosystem services, exemplified by the thermal resilience of predator communities providing biological pest control. Field assays revealed substantial differences in the temperature-dependent activity of predator species and indices of thermal resilience varied among predator communities occupying different fields. Predator assemblages with higher thermal resilience provided more stable pest control in microcosms where the temperature was experimentally varied, confirming that the index of thermal resilience developed here is linked to predator function. Importantly, complex landscapes containing a high number of non-crop habitat patches were more likely to contain predator communities with high thermal resilience. Thus, the conservation and restoration of non-crop habitats in agricultural landscapes-practices known to strengthen natural pest suppression under current conditions-will also confer resilience in ecosystem service provisioning to climate change.

Land-use intensity affects the potential for apparent competition within and between habitats.

Arthropod communities dwelling in adjacent habitats are able to impact one another via shared natural enemies. In agricultural landscapes, drastic differences in resource availability between crop and non-crop habitats cause variation in insect herbivore densities over short distances, potentially driving inter-habitat effects. Moreover, the composition of the landscape in which the habitats are embedded likely affects realised attack rates from natural enemies via impacts on local arthropod community structure. Here, we examine indirect effects between herbivore species within and between habitat types by calculating the potential for apparent competition between multiple populations. Firstly, we aim to determine how disparities in resource availability impact the strength of the potential for apparent competition occurring between habitats, secondly to examine the impact of landscape composition upon these effects, and finally to couch these observations in reality by investigating the link between the potential for apparent competition and realised attack rates. We used DNA metabarcoding to characterise host-parasitoid interactions within two habitat types (with divergent nutrient inputs) at 11 locations with variable landscape composition within an agroecosystem context. We then used these interaction networks to estimate the potential for apparent competition between each host pair and to compare expected versus realised attack rates across the system. Shared natural enemies were found to structure host herbivore communities within and across habitat boundaries. The size of this effect was related to the resource availability of habitats, such that the habitat with high nutrient input exerted a stronger effect. The overall potential for apparent competition declined with increasing land-use intensity in the surrounding landscape and exhibited a discernible impact on realised attack rates upon herbivore species. Thus, our results suggest that increasing the proportion of perennial habitat in agroecosystems could increase the prevalence of indirect effects such as apparent competition among insect herbivore communities, potentially leading to enhanced population regulation via increased attack rates from natural enemies like parasitoid wasps.

Active management of wildflower strips in commercial sweet cherry orchards enhances natural enemies and pest regulation services

To protect sweet cherry (Prunus avium L.) against pests in commercial orchards, pesticides are frequently used, but some have adverse environmental impacts. Natural enemies can deliver protection against pests but compared to the surrounding non-crop habitat their abundance is usually low in intensively managed agricultural systems. Wildflower interventions established for Conservation Biological Control as part of Integrated Pest Management (IPM) can reinstate habitat for natural enemies within cropped areas and enhance natural pest control. Over a three-year period, this more sustainable approach to crop protection was investigated in eight sweet cherry orchards protected under polytunnels in the West Midlands (UK). Wildflower strips were established in alleyways between rows of cherry trees and managed under two cutting regimes, Standard Wildflower Strips (SWS) (a single cut in late September) and Actively Managed Wildflower Strips (AMWS) (regularly cut to a height of 20 cm throughout the growing season). These were compared to unsown Control Strips (CS) (original vegetation dominated by grass species). To investigate natural enemy populations and pest regulation services, direct search, Vortis suction sampling, beat sampling, and aphid bait cards were used. Araneae (40.0% of records) and parasitoid wasps (22.7%) were the most frequent natural enemies recorded in alleyways, whilst Anystidae (51.8%) and Araneae (20.8%) were most abundant on cherry trees. Wildflower treatments almost doubled the abundance of natural enemies in alleyways, and increased abundance in cherry trees by ~15% compared to the CS. Wildflower strips increased predation of aphids (bait cards) in cherry trees by 25%. No difference in natural enemy abundance, richness or pest control was recorded between the two wildflower management regimes. Differences in natural enemy abundance and predation rates were detected despite the continued use of pesticides by growers (an average of 5.4 (± 0.4) applications per orchard per year). This study demonstrates that creating wildflower habitat in commercial sweet cherry orchards under polytunnels can boost natural enemies and the associated pest regulation services. Relative to CS, the novel grower-friendly approach of maintaining wildflower strips at a height of 20 cm with regular cutting increased flower resource availability and pest regulation services, demonstrating the potential for growers to adopt this approach as part of a robust IPM strategy.