scholarly journals Organic farming expansion drives natural enemy abundance not diversity in agricultural landscapes

2019 ◽  
Author(s):  
Lucile Muneret ◽  
Arthur Auriol ◽  
Olivier Bonnard ◽  
Sylvie Richart-Cervera ◽  
Denis Thiéry ◽  
...  
Keyword(s):  
Biodiversity Conservation ◽  
Organic Farming ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Farming Systems ◽  
Crop Productivity ◽  
Agricultural Landscapes ◽  
List Type ◽  
Natural Habitats ◽  
Ecological Intensification

AbstractOrganic farming is seen as a prototype of ecological intensification able to conciliate crop productivity and biodiversity conservation in agricultural landscapes. However, how natural enemies, an important functional group supporting pest control services, respond to organic farming at different scales and in different landscape contexts remain unclear.Using a hierarchical design within a vineyard-dominated region located in southwestern France, we examine the independent effects of organic farming and semi-natural habitats at the local and landscape scales on natural enemies.We show that the proportion of organic farming is a stronger driver of species abundance than the proportion of semi-natural habitats and is an important facet of landscape heterogeneity shaping natural enemy assemblages. Although our study highlight a strong taxonomic group-dependency about the effect of organic farming, organic farming benefits to dominant species while rare species occur at the same frequency in the two farming systems.Independently of farming systems, enhancing field age, reducing crop productivity, soil tillage intensity and pesticide use are key management options to increase natural enemy biodiversity.Synthesis and Applications. Our study indicates that policies promoting the expansion of organic farming will benefit more to ecological intensification strategies seeking to enhance ecosystem services than to biodiversity conservation.

scholarly journals Linear woody landscape elements may help to mitigate leaf surface loss caused by the cereal leaf beetle

2020 ◽  
Vol 35 (10) ◽  
pp. 2225-2238
Author(s):  
Károly Lajos ◽  
Orsolya Császár ◽  
Miklós Sárospataki ◽  
Ferenc Samu ◽  
Ferenc Tóth
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Leaf Surface ◽  
Leaf Beetle ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Landscape Elements ◽  
Surface Loss ◽  
Cereal Leaf Beetle

Abstract Context Woody semi-natural habitats serve as permanent habitats and hibernation sites for natural enemies and, through spillover processes, they play an important role in the biological control of insect pests. However, this service is also dependent on the amount and configuration of the dominating woody habitat types: linear landscape elements (hedgerows, shelterbelts), and more evenly extended plantations. Relating natural enemy action to the landscape context can help to identify the effect of woody habitats on biological control effectiveness. Objectives In the Central European agricultural landscapes such as in the Hungarian lowlands, where our study took place, woody linear elements are characterised by high, while woody areal elements, mostly plantations, by low biological and structural diversity. In this study, we aimed to determine which composition and configuration of woody linear and areal habitats in the landscape may enhance the effect of natural enemy action on plant damage caused by the cereal leaf beetle (CLB, Oulema melanopus). Methods Herbivory suppression by natural enemies was assessed from the leaf damage difference between caged and open treatments. These exclusion experiments were carried out in 34 wheat fields on plants with controlled CLB infections. The results were related to landscape structure, quantified by different landscape metrics of both woody linear and areal habitats inside buffers between 150 and 500 m radii, surrounding the wheat fields. Results The exclusion of natural enemies increased the leaf surface loss caused by CLBs in all fields. Shelterbelts and hedgerows in 150–200 m vicinity of the wheat fields had a strong suppressing effect on CLB damage, while the presence of plantations at 250 m and further rather impeded natural enemy action. Conclusions Our results indicate that shelterbelts and hedgerows may provide a strong spillover of natural enemies, thus contribute to an enhanced biological control of CLBs.

The potential of different semi-natural habitats to sustain pollinators and natural enemies in European agricultural landscapes

2019 ◽  
Vol 279 ◽  
pp. 43-52 ◽  
Author(s):  
Agustín M. Bartual ◽  
Louis Sutter ◽  
Gionata Bocci ◽  
Anna-Camilla Moonen ◽  
James Cresswell ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Agricultural Landscapes ◽  
Natural Habitats

scholarly journals Optimizing Species Richness in Mosaic Landscapes: A Probabilistic Model of Species-Area Relationships

2021 ◽  
Vol 2 ◽  
Author(s):  
Ola Olsson ◽  
Mark V. Brady ◽  
Martin Stjernman ◽  
Henrik G. Smith
Keyword(s):  
Species Richness ◽  
Biodiversity Conservation ◽  
Optimal Allocation ◽  
Optimal Solution ◽  
Average Density ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Total Size ◽  
Α Diversity ◽  
Species Area

Most landscapes are comprised of multiple habitat types differing in the biodiversity they contain. This is certainly true for human modified landscapes, which are often a mix of habitats managed with different intensity, semi-natural habitats and even pristine habitats. To understand fundamental questions of how the composition of such landscapes affects biodiversity conservation, and to evaluate biodiversity consequences of policies that affect the composition of landscapes, there is a need for models able to translate information on biodiversity from individual habitats to landscape-wide predictions. However, this is complicated by species richness not being additive. We constructed a model to help analyze and solve this problem based on two simple assumptions. Firstly, that a habitat can be characterized by the biological community inhabiting it; i.e., which species occur and at what densities. Secondly, that the probability of a species occurring in a particular unit of land is dictated by its average density in the associated habitats, its spatial aggregation, and the size of the land unit. This model leads to a multidimensional species-area relation (one dimension per habitat). If the goal is to maximize species diversity at the landscape scale (γ-diversity), within a fixed area or under a limited budget, the model can be used to find the optimal allocation of the different habitats. In general, the optimal solution depends on the total size of the species pool of the different habitats, but also their similarity (β-diversity). If habitats are complementary (high β), a mix is usually preferred, even if one habitat is poorer (lower α diversity in one habitat). The model lends itself to economic analyses of biodiversity problems, without the need to monetarize biodiversity value, i.e., cost-effectiveness analysis. Land prices and management costs will affect the solution, such that the model can be used to estimate the number of species gained in relation to expenditure on each habitat. We illustrate the utility of the model by applying it to agricultural landscapes in southern Sweden and demonstrate how empirical monitoring data can be used to find the best habitat allocation for biodiversity conservation within and between landscapes.

scholarly journals Landscape composition mediates suppression of major pests by natural enemies in conventional cruciferous vegetables

2021 ◽  
Author(s):  
Jie Zhang ◽  
Shijun You ◽  
Dongsheng Niu ◽  
Karla Giovana Gavilanez Guaman ◽  
Ao Wang ◽  
...  
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Positive Impact ◽  
Spatial Scales ◽  
Habitat Diversity ◽  
Landscape Composition ◽  
Dispersal Ability ◽  
Cruciferous Vegetables ◽  
Natural Habitats

ABSTRACTBackgroundConservation biological control provides an environment-friendly approach to improve the efficacy of natural enemies. Although numerous studies have demonstrated the potential of semi-natural habitats in promoting biological control in organic or unsprayed agroecosystems, few studies were conducted in conventional agricultural fields. In this study, we investigated the effects of landscape composition on the major pests of cruciferous vegetables and on the assemblages of their natural enemies in southeastern China.ResultsHabitat diversity, particularly increasing grassland proportion in the landscape, had a positive impact in controlling both small-sized pests (aphids, leaf miners, thrips and flea beetles) and Plutella xylostella. This increasing proportion also promoted greater abundance and diversity of canopy-dwelling predators, more forests supported a higher diversity of airborne enemies (parasitoids and canopy-dwelling predators) as well as a higher abundance of ground-dwelling predators. A general increase in habitat diversity was beneficial to parasitoids and ground-dwelling predators. Additionally, the proportion of forest, grassland, and non-cruciferous vegetable area, as well as habitat diversity, affected the compositions of natural enemy communities. Moreover, inconsistent effects of non-cruciferous and grassland habitats were found between sampling regions for small-sized pests and canopy-dwelling predators. Moreover, the scale at which pests and natural enemies’ abundance and richness responded most to landscape composition varied with their feeding range and dispersal ability.ConclusionOur study provides evidence that increasing the amount of semi-natural habitats and habitat diversity can result in lower pest and higher natural enemy abundance in conventional cruciferous agroecosystems. Regional conditions and spatial scales also should be considered in designing the agricultural landscape mosaic.

scholarly journals Toxicity of Insecticides and Miticides to Natural Enemies in Australian Grains: A Review

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 187
Author(s):  
Kathy Overton ◽  
Ary A. Hoffmann ◽  
Olivia L. Reynolds ◽  
Paul A. Umina
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Current Knowledge ◽  
Farming Systems ◽  
International Organization ◽  
Carabid Beetles ◽  
Generalist Predators ◽  
Seed Treatments ◽  
Target Effects

Continued prophylactic chemical control to reduce pest populations in Australian grain farming systems has limited the effectiveness of biological control via natural enemies in crops within an integrated pest management (IPM) framework. While a variety of data is available to infer potential non-target effects of chemicals on arthropod natural enemies, much of it may be irrelevant or difficult to access. Here, we synthesise the literature relevant to Australian grain crops and highlight current knowledge gaps for potential future investment. A range of testing methodologies have been utilised, often deviating from standardised International Organization for Biological Control (IOBC) protocols. Consistent with findings from over 30 years ago, research has continued to occur predominantly at laboratory scales and on natural enemy families that are easily reared or commercially available. There is a paucity of data for many generalist predators, in particular for spiders, hoverflies, and rove and carabid beetles. Furthermore, very few studies have tested the effects of seed treatments on natural enemies, presenting a significant gap given the widespread global use of neonicotinoid seed treatments. There is a need to validate results obtained under laboratory conditions at industry-relevant scales and also prioritise testing on several key natural enemy species we have identified, which should assist with the adoption of IPM practices and decrease the reliance on broad-spectrum chemicals.

Dryland Organic Farming Partially Offsets Negative Effects of Highly Simplified Agricultural Landscapes on Forbs, Bees, and Bee–Flower Networks

2019 ◽  
Vol 48 (4) ◽  
pp. 826-835 ◽  
Author(s):  
Subodh Adhikari ◽  
Laura A Burkle ◽  
Kevin M O’Neill ◽  
David K Weaver ◽  
Casey M Delphia ◽  
...  
Keyword(s):  
Organic Farming ◽  
Community Composition ◽  
Natural Habitat ◽  
Farming Systems ◽  
Agricultural Landscapes ◽  
Floral Resources ◽  
Conventional Farming ◽  
No Till ◽  
Bee Diversity ◽  
Bee Abundance

AbstractIndustrialized farming practices result in simplified agricultural landscapes, reduced biodiversity, and degraded species-interaction networks. Thus far, most research assessing the combined effects of farming systems and landscape complexity on beneficial insects has been conducted in relatively diversified and mesic systems and may not represent the large-scale, monoculture-based dryland agriculture that dominates many regions worldwide. Specifically, the effects of farming systems on forbs, bees, and their interactions are poorly understood in highly simplified dryland landscapes such as those in the Northern Great Plains, United States, an area globally important for conventional and organic small grain, pulse, forage, and oilseed production. During a 3-yr (2013–2015) study, we assessed 1) the effects of dryland no-till conventional and tilled organic farming on forbs, bees, and bee–flower networks and 2) the relationship between natural habitat and bee abundance. Flower density and richness were greater in tilled organic fields than in no-till conventional fields, and forb community composition differed between farming systems. We observed high bee diversity (109 taxa) in this highly simplified landscape, and bee abundance, richness, and community composition were similar between systems. Compared with tilled organic fields, bee–flower interactions in no-till conventional fields were poorly connected, suggesting these systems maintain relatively impoverished plant-pollinator networks. Natural habitat (11% of the landscape) did not affect small-bodied bee abundance in either farming system but positively affected large-bodied bees within 2,000 m of crop-field centers. In highly simplified agricultural landscapes, dryland organic farming and no-till conventional farming together support relatively high bee diversity, presumably because dryland organic farming enhances floral resources and bee–flower networks, and no-till management in conventional farming provides undisturbed ground-nesting habitats for wild bees (Hymenoptera: Apoidea).

scholarly journals The impact of conventional and organic farming on soil biodiversity conservation: a case study on termites in the long-term farming systems comparison trials in Kenya

BMC Ecology ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
John J. Anyango ◽  
David Bautze ◽  
Komi K. M. Fiaboe ◽  
Zipporah O. Lagat ◽  
Anne W. Muriuki ◽  
...  
Keyword(s):  
Biodiversity Conservation ◽  
Organic Farming ◽  
Farming Systems ◽  
Soil Biodiversity ◽  
The Impact

scholarly journals Mixed effects of ecological intensification on natural pest control providers: a short-term study for biotic homogenization in winter wheat fields

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8746
Author(s):  
Zoltán Elek ◽  
Jana Růžičková ◽  
Réka Ádám ◽  
Krisztina Bereczki ◽  
Gergely Boros ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Pest Control ◽  
Natural Enemies ◽  
Landscape Scale ◽  
Biotic Homogenization ◽  
Natural Habitats ◽  
Ecological Intensification ◽  
Field Management ◽  
Invertebrate Assemblages ◽  
Aphid Abundance

Agricultural intensification is one of the major drivers of biotic homogenization and has multiple levels ranging from within-field management intensity to landscape-scale simplification. The enhancement of invertebrate assemblages by establishing new, semi-natural habitats, such as set-aside fields can improve biological pest control in adjacent crops, and mitigate the adverse effect of biotic homogenization. In this study we aimed to examine the effects of ecological intensification in winter wheat fields in Hungary. We tested how pests and their natural enemies were affected at different spatial scales by landscape composition (proportion of semi-natural habitats in the surrounding matrix), configuration (presence of adjacent set-aside fields), and local field management practices, such as fertilizer (NPK) applications without applying insecticides. We demonstrated that at the local scale, decreased fertilizer usage had no direct effect either on pests or their natural enemies. Higher landscape complexity and adjacent semi-natural habitats seem to be the major drivers of decreasing aphid abundance, suggesting that these enhanced the predatory insect assemblages. Additionally, the high yield in plots with no adjacent set-aside fields suggests that intensive management can compensate for the lower yields on the extensive plots. Our results demonstrated that although complexity at the landscape scale was crucial for maintaining invertebrate assemblages, divergence in their response to pests and pathogens could also be explained by different dispersal abilities. Although the landscape attributes acted as dispersal filters in the organization of pest and pathogen assemblages in croplands, the presence of set-aside fields negatively influenced aphid abundance due to their between-field isolation effect.

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