Flower Strips Research Articles

Perennial flower margins reduce orchard fruit damage by rosy apple aphid, Dysaphis plantaginea (Homoptera: Aphididae)

Abstract Sown or natural flower strips are a commonly used management practice in agroecosystems and have been demonstrated to increase the abundance of predators of orchard pests. There is less evidence of the extent to which such strips can reduce pest damage in orchards. Here we examined the effect of managed, perennial flower margins on fruit damage by an economically significant crop pest, Dysaphis plantaginea, rosy apple aphid, in conventional apple orchards over 2 years, compared to orchards without flower margins. We found orchard flower margins reduced the percentage of apple trees with fruit damage by D. plantaginea, from 80% to 48%. In 2021, a period of severe infestation (65% of trees had fruit damage), there was reduced spread of D. plantaginea on infested apple trees and the number of trees with fruit damage was significantly reduced up to 50 m into orchards. During 2022, a period of lower infestation (25% of trees damaged), fruit damage was significantly reduced up to 10 m from the flower margin. A significant reduction in predation of aphids from bait cards in flower margin compared with control orchards suggests specialists, rather than generalist predators, may be driving the positive effects of the margin on pest pressure. There was no significant effect of flower margins on abundance of important aphid predators, including Syrphidae (hoverflies) and Coccinellidae (ladybirds). Synthesis and applications: To our knowledge, this study is the first to detect a reduction in fruit damage by pests at harvest in orchards with a flower margin. We highlight the potential for established perennial flower margins to deliver measurable, sustainable, D. plantaginea control benefits and provide insights into the optimal spatial arrangement of flower strips in orchards.

The effectiveness of intercropping and agri-environmental schemes on ecosystem service of biological pest control: a meta-analysis

Plant diversification contributes to the ecological intensification of agroecosystems through pest biocontrol services provision. However, the existing evidence for the effectiveness of plant diversification in enhancing pest biocontrol services is highly uncertain across features of plant diversity and biodiversity characteristics. We undertook a comparative meta-analysis focusing on three essential crops (wheat, maize, and soybean) to investigate how diversification schemes in-field (intercropping) and Agri-environmental scheme (AES) around the field (flower strip, hedgerow and field margin) affect arthropod abundance. A random effects analysis was used to determine the role of 10 key factors underlying the effectiveness of plant diversification including biodiversity level and habitat, main and companion plant species, intercropping arrangement, the growth stage of the main crops, type of AES planting scheme, AES planting width, distance from AES plantings and geographical latitude. The overall results revealed that intercropping reduced herbivore and boosted predators and parasitoids abundance significantly, while AES successfully increased predators but not herbivores. Maize intercropping with legume and non-legume plants and row intercropping allowed for effective pest management. The abundance of predators increased in wheat fields immediately adjacent to planting around the field (AES), but this effect declined beyond 5 m from the flower strips. Our results suggest that the response of arthropod abundance to plant diversification is a compromise between spatial management scale, ecological characteristics of arthropod and plant diversification features. These results offer promising pathways for optimizing plant diversification schemes that include functional farm biodiversity across spatial and temporal scales and designing multi-functional landscapes.

Bee-diverse habitats positively affect seed set in wild plant species

IntroductionInteractions between flowering plants and visiting wild bees are crucial for ensuring pollination and subsequent plant reproductive success. However, bee diversity in an area has rarely been recorded in relation to seed set in native plants. In this project, we investigated the effect of local wild bee communities on seed set in four common wild plant species.MethodsPotted plants of Centaurea jacea, Cichorium intybus, Sinapis arvensis, and Salvia pratensis were placed for pollination experiments, in two distinct habitat types that we expected to show distinct bee communities, namely near-natural grassland and perennial wild flower strips, in Germany.ResultsOur results showed that near-natural grassland had a higher bee species richness and an increased seed set compared with flower strips that displayed a higher bee abundance in most study locations. Although we found effects of bee diversity on seed set, we did not detect a significant effect of bee abundance. Furthermore, the seed set in response to wild bee diversity differed across the plant species.DiscussionWe conclude that bee-friendly habitats ensure a high seed set in wild plants, but that the impact varies between different plant species.

Flower Strips as an Ecological Tool to Strengthen the Environmental Balance of Fields: Case Study of a National Park Zone in Western Poland

Maintaining biodiversity in agrocenoses is becoming an important element of sustainable development strategies. Flower strips can perform various functions, and their use in the agricultural landscape is a form of a natural mechanism for regulating the agricultural habitat and improving the effectiveness of biological methods of combating crop pests. This manuscript is a case study in Wielkopolska National Park, a valuable wildlife area situated in a temperate zone characteristic of the climate conditions of western Poland. The purpose of this study was to analyze the species composition of plants in a flower strip two years after sowing a mixture of seeds of perennial plants, and to determine the diversity of the collected arthropods depending on the flowering intensity of plants in the strip. The most intense flowering period in the flower strip occurred in June, when the number of flowering plants was the highest and belonged to one species, Trifolium repens (81.52% of all flowering plants). In the same month, the largest share of beneficial arthropods were specimens from Hymenoptera/Parasitica (29.15%), which may indicate their preference for T. repens. The share of beneficial arthropods in relation to all caught arthropods was higher in June (58.74%) than in July (35.16%), with Hymenoptera predominating, represented mainly by Parasitica, which may indicate their preference for species from the genus Trifolium.

No evidence for competition over floral resources between winter-active parasitoids and pollinators in agroecosystems

Warming temperate winters are resulting in increased insect winter activity. With modern agroecosystems largely homogenous, characterised by low floral diversity, competitive interactions may arise between flower-visiting species, with potential implications for the ecosystem services they provide (e.g. biological control and pollination). Flower strips may be implemented during winter months to support flower-visiting insects and enhance ecosystem service provision. Employing field trials conducted in Brittany, France between 2019 and 2021 and laboratory cage experiments, the current study examined the impact of winter flower strips on aphid biological control performed by parasitoid wasps and the potential for competitive interactions between winter-active parasitoids and pollinators. Results revealed that parasitism rate was not enhanced by the presence of winter flower strips. This lack of effect was not the consequence of pollinator presence, and the current study found no effect of pollinator abundance on parasitism rate. Flower strips may thus be implemented during winter months to support nectar-feeding insects when floral resources are scarce, with no evidence of exploitative competition between pollinators and parasitoids, nor a detrimental impact on biological control provision.

Do agri-environment schemes enhance carbon sequestration? Quantifying the effort in the Czech Republic

In the Czech Republic, there are several agri-environment schemes focused on biodiversity and improved soil conditions with added benefits contributing to carbon sequestration introduced by the Common Agricultural Policy (CAP) in 2002. In this study, our aim was to analyse historical data of implemented measures with the highest potential for carbon sequestration, assess their outputs and determine which of the agri-environment measures contributed the most during the programming periods and over the twenty years. Apart from analysing historical data (e.g. number of applications, enrolled area and received payment) and assessing their outputs based on sequestration coefficients published in the literature, we have created an algorithm that predicted carbon sequestration over a twenty-year period to assess the contribution of specific measures beyond the duration of programmes. All the sub-measures monitored contributed to carbon sequestration, with the resulting value determined by the amount of land on which the measure was implemented. The results indicate that, over the period under study, the Conversion from Arable Land to Grassland sub-measure was the highest contributor, reaching values of 555,803–606,330 t C and 1,129,317–1,538,235 t C over twenty years. However, the conversion from arable land to grassland is limited by the land suitable for conversion, so it can be assumed that the Catch Crops sub-measure will make a higher contribution in the future. For the period under study, Catch Crops contributed 359,352–598,920 t C. An increase is also expected for the Flower Strips sub-measure. The study advances knowledge on the contribution of agri-environment measures to carbon sequestration and their modelling, a topic that has not been addressed by many researchers to date and is the first of its kind in Central Europe.

Benefits of Cross-Pollination in Vegetable Soybean Edamame

Dependence on cross-pollination varies widely among wild and cultivated plant species. Even among crops that are less dependent on outcrossing, such as soybean (Glycine max L.), cross-pollination can improve fruit quality and commercial value. There is a growing body of literature regarding the role of insect pollination in soybean; however, there is a knowledge gap on the intersection between the reproductive system of soybean and its pollination ecology. To address this gap, we first sought to characterize the reproductive system of vegetable soybean (edamame) in terms of benefits and reliance on outcrossing using three traditional experimental pollination scenarios in field conditions: open pollination, automatic selfing (pollinator-exclusion), and hand cross-pollination (controlled crossing). We also tested whether proximity to floral supplements planted on one edge of the field affected its reproductive outputs, and surveyed the floral visitors of the crop. Overall, we found a significant increase in fruit weight among open-pollinated plants compared to those in the automatic selfing treatment, with this effect accentuated with proximity to the flower strip. Despite open pollinated flowers having 30% higher flower abortions rates compared to automatic selfing, the number of developed seeds per fruit was similar among these treatments, with open-pollination having a greater proportion of commercial grade-A fruits. Additionally, grade-A fruits in open-pollination and hand cross-pollination treatments were similar in weight, both of which were significantly heavier than those in the automatic selfing treatment. Although edamame can automatically self, our results suggest that reproductive outputs including fruit weight and number of commercial grade-A fruits are positively affected by cross-pollination and proximity to floral supplements.

“Three-strip management”: introducing a novel mowing method in perennial flower strips and grass margins to increase habitat complexity and attractiveness for pollinators

Flower margins are widely adopted as agri-environment measure (AEM) to enhance farmland biodiversity. However, perennial flower margins need appropriate mowing schemes to manage succession, especially in regions with high nitrogen depositions, and current schemes inadequately address the needs of arthropods, including pollinators. Effective management should provide floral diversity with staggered flowering times, creating varied sward structures for diverse habitats that support shelter, nesting, and mating sites. To address these challenges, a novel mowing method, called 'Three-strip management,' is proposed. This method involves dividing the margin into three strips using curved instead of straight mowing lines. During each cycle, one third remains unmown for shelter, while clippings are removed to lower soil nutrient status and reduce succession. The use of overlapping curved mowing lines aims to maximize variety in patterns, fostering spatio-temporal variation in the (re)growth of perennials and swards. Unlike Regular rotational management, multiple uneven parts are kept unmown over winter, increasing the number of subzones in different mown states over successive years. In this study, field trials comparing Three-strip management with Regular rotational management reveal positive effects especially during the second year, including higher bee abundance and diversity. Plant-pollinator networks also demonstrate increased interactions. While the study focuses on bees, the potential of the Three-strip management to support other beneficial insects is discussed. Given declining insect populations in agricultural landscapes, this paper offers insights into enhancing perennial flower margins as AEM to support pollinator populations. The novel Three-strip management presents a promising strategy for balancing management needs with diverse insect requirements, contributing to sustainable biodiversity conservation in agricultural settings.

Enhancing Coccinella Beetle Biological Pest Control via a Floral Approach in Cucumber Greenhouse.

Flower-rich habitats are crucial for promoting biodiversity and ecosystem services within agricultural ecosystems, such as pollination and pest control. The present study investigates the efficacy of employing floral structures as a criterion for the selection of plant species in order to enhance the attraction of natural enemies within cucumber greenhouses, consequently augmenting floral resources. The results of our study provide evidence that flower strips have a beneficial effect on the fitness of critical natural predators, while not facilitating the proliferation of detrimental insect species. These findings exhibit potential for enhancing pest-management services in the agricultural sector. The findings of our study demonstrate that pest levels within greenhouse environments closely resemble those observed in real-world commercial cropping systems. As a result, the introduction of Coccinella septempunctata and Menochilus sexmaculatus biocontrol agents is confirmed to be a reliable and efficient method for pest management. The phenomenon of predator-prey density dependency is recognized as a crucial element in the implementation of biological control strategies. Furthermore, we investigate the impact of floral resources on the reproductive capacity of indigenous predators. The impact of Coriandrum sativum on fertility is substantial, indicating that the presence of a varied plant assortment with overlapping flowering periods can prolong the availability of floral resources. This study highlights the significance of flower-rich habitats and deliberate plant selection in augmenting biodiversity, ecosystem services, and pest management within agricultural settings. The implementation of conservation biological control technologies presents supplementary ecological advantages, thus offering practical implications for the promotion of sustainable agricultural practices.

The contributions of flower strips to wild bee conservation in agricultural landscapes can be predicted using pollinator habitat suitability models

Abstract Sowing flower strips along field edges is a widely adopted method for conserving pollinating insects in agricultural landscapes. To maximize the effect of flower strips given limited resources, we need spatially explicit tools that can prioritize their placement, and for identifying plant species to include in seed mixtures. We sampled bees and plant species as well as their interactions in a semi‐controlled field experiment with roadside/field edge pairs with/without a sown flower strip at 31 sites in Norway and used a regional spatial model of solitary bee species richness to test if the effect of flower strips on bee species richness was predictable from the modelled solitary bee species richness. We found that sites with flower strips were more bee species rich compared to sites without flower strips and that this effect was greatest in areas that the regional solitary bee species richness model had identified to be particularly important for bees. Spatial models revealed that even within small landscapes there were pronounced differences between field edges in the predicted effect of sowing flower strips. Of the plant species that attracted the most bee species, the majority mainly attracted bumblebees and only few species also attracted solitary bees. Considering both the taxonomic diversity of bees and the species richness of bees attracted by plants we suggest that seed mixes containing Hieracium spp. such as Hieracium umbellatum, Pilosella officinarum, Taraxacum spp., Trifolium repens, Lotus corniculatus, Stellaria graminea and Achillea millefolium would provide resources for diverse bee communities in our region. Spatial prediction models of bee diversity can be used to identify locations where flower strips are likely to have the largest effect and can thereby provide managers with an important tool for prioritizing how funding for agri‐environmental schemes such as flower strips should be allocated. Such flower strips should contain plant species that are attractive to both solitary and bumblebees, and do not need to be particularly plant species rich as long as the selected plants complement each other.

Diversified Rice Farms with Vegetable Plots and Flower Strips Are Associated with Fewer Pesticide Applications in the Philippines.

Ecological engineering is defined as the design of sustainable ecosystems for the benefit of both human society and the environment. In Southeast Asia, researchers have applied ecological engineering by diversifying farms using flower strips to restore regulatory services to rice ecosystems and thereby reduce herbivore-related yield losses and overall pesticide use. We conducted a survey of 302 rice farmers across four regions of the Philippines to assess their farm diversification practices and determine possible associations with pesticide use. Rice was the main product on all farms; however, the farmers also produced fruits and vegetables, either rotated with rice (47% of the farmers) or in small plots in adjacent farmland. In addition, 64% of the farmers produced flowers, herbs, and/or vegetables on rice bunds. Vegetables were cultivated mainly to supplement household food or incomes, but 30% of the farmers also believed that the vegetables reduced pest and weed damage to their rice. We found that 16% of the farmers grew flowers on their bunds to reduce pest damage to rice and vegetables, and many farmers applied botanical extracts, growth stimulants, and insect traps to reduce damage to the vegetables. Some farmers avoided insecticides on rice by using Trichogramma cards. Planting flowers on rice bunds, rearing ducks in the rice fields, and farmers' recognition of beneficial rice arthropods were statistically significantly associated with lower pesticide (particularly, insecticide) applications to rice. Our results indicate that farm diversification to produce supplementary foods for rural households and access to alternative pest management options can reduce pesticide use on rice farms in tropical Asia.

Aphid biological control in arable crops via flower strips: The predominant role of food resources over diversity effects

Abstract Plant taxonomic and functional diversity promotes interactions at higher trophic levels, but the contribution of functional diversity effects to multitrophic interactions and ecosystem functioning remains unclear. In agroecosystems, flower strips can be sown to promote biodiversity and associated services, but their plant composition is poorly considered from a functional diversity perspective so as to promote multitrophic interactions. In a field experiment, aphid biological control was compared across contrasting flower strip mixtures, over a 4‐year arable crop rotation. The effects of plants providing food resources, that is nectar and legumes supporting alternative hosts and prey, and the effects of plant species richness and functional dispersion were investigated on the biological control of aphid populations. In general, increases in the percentage of plant cover providing nectar and alternative prey (Fabaceae) to natural enemies increased predator–prey ratios and aphid parasitism and decreased aphid population growth rates. These effects however depended on the crop species. Species richness and the functional dispersion of traits involved in plant–arthropod interactions were of lesser importance, and the directions of their effects were crop‐specific. Synthesis and applications. These findings provide useful insight for designing perennial plant mixtures for creating or restoring habitats supporting aphid regulation. It is not adequate to sow any mixture containing simply flowering plants. Plant mixtures should comprise a large proportion of plant species supporting alternative prey, like legumes, and species producing nectar being easily accessible to natural enemies (corollas with nondeep nectar). To be efficient over a crop rotation, with aphids being present at different seasons, these nectar resources should be provided throughout the year thanks to a diversity of plant flowering periods.

Escaping the Lock-in to Pesticide Use: Do Vietnamese Farmers Respond to Flower Strips as a Restoration Practice or Pest Management Action?

Ecological engineering using linear flower strips is proposed as an alternative to insecticide-based rice pest management. However, its success depends on farmers’ appreciations of related interventions as part of an ecosystem restoration process. We examined agronomic and pest management responses to flower strips among 305 farmers surveyed at 12 villages in the Mekong Delta Region (MDR) of Vietnam. Practices by conventional farmers at the same villages were used as a baseline. The ecological engineering farmers mainly integrated flower strips with pest management practices by reducing insecticide applications before 40 days after rice crop establishment (ca 38% of farmers; 9% more than on conventional farms). Flower strips were also associated with less frequent and irregular insecticide applications or with insecticide-free rice (i.e., possibly IPM: ca 19% of ecological engineering farmers). Otherwise, farmers (ca 43% of ecological engineering farmers) continued to apply insecticides prophylactically and, in some cases, applied more insecticides than their conventional neighbors. Flower strips were not associated with reductions in any other pesticides. Reported yields were not directly affected by flower strips or pesticide inputs. Our results suggest that ecological engineering was not widely regarded by participating farmers as an ecosystem restoration practice, but rather, as a pest management action. Further promotion of flower strips as a component of ecosystem restoration is required to break the lock-in to pesticide use at ecologically engineered rice farms in the MDR.

First steps of pollinator-promoting interventions in Eastern European urban areas – positive outcomes, challenges, and recommendations

Urbanisation has a strong role in pollinator decline, while properly managed green spaces could promote pollinators – especially bees and butterflies – by providing foraging and nesting habitats in cities. In public spaces, several opportunities exist to help pollinators including rare mowing, flower strip sowing, and bee hotel establishment. However, pollinator-promoting interventions are almost lacking and still understudied in Eastern Europe. We aimed to investigate the impact of rare mowing and annual flower-sowing interventions on pollinators, floral resources, and vegetation attributes in three case studies within Hungary. We compared treatment (extensively mown or sown) and control (intensively mown) site pairs during five sampling occasions within a season. We found positive, but due to the severe drought and management inaccuracies relatively minor effect of both interventions. The extensively mown sites presented higher and greener vegetation with more flowers and pollinators. The sown flower patches provided floral resources and supported the pollinators in the second half of the season, while they were scarcely visited in spring and early summer due to the annual soil scarification and re-sowing. Although the two types of interventions could complement each other during the season, there is room for further improvements. To reach resilient urban ecosystems against climate and environmental changes, we recommend using primarily native and mostly perennial seeds, combining intervention types, planning for the long-term, and avoiding management inaccuracies (e.g. unplanned mowing). Promoting and monitoring plant-pollinators systems may increase the diversity and human well-being in cities, while citizens’ involvement can facilitate these interventions.

Earthworm and soil microbial communities in flower strip mixtures

AimsIncorporation of flower strips is an agricultural measure to increase aboveground biodiversity and ecosystem services. Although soil communities are key components of terrestrial biodiversity and drive important ecosystem services, their abundance, diversity, and composition in flower strips remain largely unexplored. Here, we shed light on earthworms and soil microorganisms in flower strips.MethodsWe sowed a grassy field margin vegetation as well as two annual and two perennial flower strip mixtures in fully randomized plots of 9 × 28 m in three different types of soil in Germany. Two years following sowing, we determined earthworm communities using chemical extraction and investigated the soil microbiome using real-time PCR (archaea, bacteria, fungi, and soil-N-cycling genes) and amplicon sequencing (bacteria and fungi).ResultsDifferent plant mixtures (i.e. field margin, annual and perennial flower strips) harbored distinct earthworm and soil microbial communities. Earthworm density and biomass declined or remained unaffected in annual flower strips but increased in perennial flower strips as compared to the field margins. Arbuscular mycorrhizal fungi showed greater diversity and relative abundance in non-tilled (i.e. field margin and perennial flower strips) than in tilled plant mixtures (i.e. annual flower strips).ConclusionsWe attribute changes in earthworm and microbial communities mainly to the effect of tillage and plant diversity. Overall, we suggest that perennial flower strips serve as refugia. Future studies should compare soil biota in perennial flower strips to those in adjacent fields and investigate whether the promotion of soil communities extends into adjacent fields (‘spillover’).

Flowering Coriander (Coriandrum sativum) Strips Do Not Enhance Ecosystem Services in Azorean Orchards.

The effect of flower strips on ecosystem services (ESs) and disservices (EDs) is routinely assessed following changes in service provider densities without measuring the associated levels of ES/EDs. By using the sentinel approach (i.e., exposing a plant, seeds, and prey models in a standardized way), we tested how coriander (Coriandrum sativum) strips planted in mixed orchards on Terceira Island (Azores, Portugal) affected herbivory on lettuce plants, seed predation on wheat and weed seeds, and predation on artificial caterpillars. Vertebrates had more influence than invertebrates on ESs/EDs. Herbivory (ED) after 2 weeks was similar in the coriander and the control plots (mean ± SD; 2.3% ± 3.3% vs. 2.2% ± 2.9%, n = 32 for both). Seed predation was higher in the control than in the coriander plots for both grain (ED; 30.8% ± 38.9% vs. 15.3% ± 10.8%, n = 18 for both) and weed seeds (ES; 2.5% ± 4.1% vs. 0.4% ± 0.5%, n = 18 for both). Vertebrate predation (ES) rates after 48 h were significantly higher in the control (estimate 9%, 95% CI: 4-20%) than in the coriander plots (3%, 1-8%), while no difference was observed for invertebrate predation. Coriander strips did not support increased ES/reduced ED levels in this setting. The tools used can be effective to quantitatively compare multiple ESs/EDs under different farming management strategies.

Biodiversity measures providing food and nesting habitat increase the number of bumblebee (Bombus terrestris) colonies in modelled agricultural landscapes

Individual biodiversity measures in agricultural landscapes such as flower strips are reported to promote the diversity and abundance of pollinating insects. Those biodiversity measures can be important food sources increasing the amount and continuity of pollen and nectar supply besides sometimes also offering nesting and hibernation sites. Still little is known about combined effects of biodiversity measures at the landscape scale and their long-term impact on pollinator population development. We used the agent-based simulation model BumbleBEEHAVE to investigate, if biodiversity measures have a positive effect on bumblebee populations at landscape scale in terms of the number of colonies per hectare. For this purpose, we chose Bombus terrestris, the most common bumblebee species in Germany, as target species. We used three real landscapes located in different regions of Germany as landscape settings for the simulations. The landscapes had strongly different farming systems regarding crop diversity and rotations and, consequently, different spatial structure and areal proportions of land-use types and semi-natural habitats. Between 2017 and 2020, distinct combinations of biodiversity measures, such as flower strips, flowering headland and fallows, were established by farmers on different areal proportions of the three landscapes. The biodiversity measures differed in plant-seed mixtures and, thus, the pollen and nectar supply by plants. We simulated the development of bumblebee colonies in the landscapes with and without the implemented biodiversity measures over eight years (four years in a twice repetition). We found that the implementation of biodiversity measures had a significant positive effect on the number of colonies. Further analysis showed that the pollen and nectar supplied by biodiversity measures had positive effects in all three landscapes, while the effect of additional nesting habitat differed among landscapes. Mass-flowering crops had little to no significant effect on the number of bumblebee colonies, whereas semi-natural habitats had a markedly positive effect. Our study underlines that not only biodiversity measures are likely to affect the bumblebee population, but that the overall landscape composition, particularly proportion of semi-natural habitats, is also important. So, to achieve high effectiveness of biodiversity measures, landscape context may be taken into account.

Flower strip effectiveness for pollinating insects in agricultural landscapes depends on established contrast in habitat quality: A meta‐analysis

Abstract Flower strips have become a prevalent measure in agricultural landscapes to counteract biodiversity loss and especially promote pollinators. Although their benefits for pollinating insects have been frequently evaluated and reported, generalized conclusions about optimal settings for effective flower strips are still difficult. From the perspective of pollinators, flower strips vary distinctly in habitat quality, and the same applies for the control sites selected for scientific studies. In this study, we used a meta‐analytic approach based on a systematic review of recent studies (2009–2020) to analyze the relationship between flower strip effectiveness for pollinators and the contrast in habitat quality between flower strips and control sites. We extracted 350 data entries from 29 of 172 studies based on available data for richness or abundance of the pollinator taxa groups Apiformes, Lepidoptera and Syrphidae as response variables, for both flower strips and control treatments. All flower strips and control treatments were assigned a habitat quality score including information on spatial dimension, floral resources and management. Moreover, we included information on landscape complexity as measured by percent cover of seminatural habitats in the studied landscape. In general, our results of meta‐analytical models showed an increasing effect size of flower strips on pollinators for higher contrasts in habitat quality between flower strips and control treatments. This relationship was consistent across pollinator taxa and different levels of landscape complexity. Altogether, in terms of pollinator habitat quality, high‐quality flower strips were more attractive than low‐quality flower strips, and the reported effectiveness of flower strips decreased from low‐quality to high‐quality control treatments. We recommend that results of future studies evaluating flower strips for pollinators are always linked with the contrast in habitat quality between selected flower strips and control treatments.

Unlike woodland edges, flower strips do not act as a refuge for cabbage stem flea beetle aestivation.

Semi-natural habitats are generally considered to be beneficial to natural enemies of crop pests and pollinators. However, they could also be used by pests, such as the Cabbage Stem Flea Beetle (CSFB), Psylliodes chrysocephala, a major pest of winter oilseed rape, Brassica napus. Adults emerge from pupation in late spring and move to aestivation habitats. Published reports identify forest edges as the major shelter used, but flower strips may also constitute an alternative habitat. This study aimed to: (i) determine the role of perennial flower strips in CSFB aestivation in comparison with woodland edges; (ii) determine the influence of landscape composition on the abundance of aestivating CSFB and (iii) identify the characteristics of the local habitat associated with a high abundance of aestivating CSFB. CSFB emergence from aestivation was monitored with emergence traps from mid-August to mid-October 2021, at 14 sites in France. We found that CSFB preferred woodland edges and did not aestivate in flower strips. We found a negative effect of percentage woodland cover only for the smallest scale studied (250 m radius). We also found positive effects of the percentage of litter and mean tree circumference on the number of aestivating CSFB in woodland edges. The aestivation of CSFB is supported by woodland edges, but not by flower strips. This implies that the presence of flower strips near oilseed rape fields does not exacerbate the problems due to this pest. However, the crops in the vicinity of woodlands could be colonized earlier by this pest than more distant fields. © 2023 Society of Chemical Industry.

Wildflower plantings have mixed effects on insect herbivores and their natural enemies

Flower strips are advocated as a strategy to promote beneficial insects as well as the services they deliver to adjacent crops. Flower strips have, however, often been developed separately for pollinators and natural enemies and, additionally, little consideration has been given to effects on insect herbivores. We sampled insect herbivores, their natural enemies and parasitism of pest eggs using vacuum sampling, sticky cards and egg cards in nine pairs of bee-attractive wildflower plantings and control field borders, as well as in adjacent tomato and watermelon crop fields in Yolo County, California 2015–2016. Control field borders had a higher total number of herbivores on sticky traps than did wildflower plantings, a pattern that was driven by more aphids, hoppers, psyllids and whiteflies, whereas wildflower plantings had more lace bugs and Lygus bugs. The total number of herbivores in the adjacent crop fields did not differ between treatments, but there were more leaf beetles near (at 10 m but not 50 m from) wildflower plantings. Control field borders had a higher total number of predators, driven by more big-eyed bugs, lady beetles and minute pirate bugs, whereas spiders were more common in wildflower plantings. The total number of predators in adjacent crop fields was, however, higher in those next to wildflower plantings, which was driven by more minute pirate bugs. Parasitoid wasps were more common in wildflower plantings and at 10 m but not 50 m into adjacent crop fields. Stink bug egg parasitism rate did not differ between treatments, either in the borders or in the crop fields. In conclusion, wildflower plantings clearly affect the insect herbivore and natural enemy community, but do so in a highly taxon-specific manner, which can lead to both positive and negative outcomes for pest control as a result.