scholarly journals Mixed-Species Gardens Increase Monarch Oviposition without Increasing Top-Down Predation

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 648
Author(s):  
Rebecca Nestle ◽  
Jaret C. Daniels ◽  
Adam G. Dale
Keyword(s):  
Biological Control ◽  
Plant Diversity ◽  
Natural Enemy ◽  
Monarch Butterfly ◽  
Urban Gardens ◽  
Top Down ◽  
Mixed Species ◽  
Natural Habitats ◽  
Specialist Insect ◽  
Habitat Design

Monarch butterfly populations have declined by over 80% in the last 20 years. Conservation efforts focus on the creation of milkweed habitats to mitigate this decline. Previous research has found monarchs lay more eggs per milkweed stem in urban gardens than natural habitats and recent work identified specific garden designs that make urban gardens more attractive to monarchs. Increasing plant diversity can reduce specialist insect herbivore colonization via bottom-up (e.g., plant) and top-down (e.g., predation) regulatory factors. Although this is beneficial for pest management efforts, it contradicts conservation efforts. In this study, we explored if adding multiple flowering species to garden-sized milkweed plantings affected monarch oviposition or top-down regulation of larvae. We compared monarch egg abundance, natural enemy abundance and richness, and biological control of monarch larvae in milkweed monocultures and milkweed mixed with four additional wildflower species. We found that monarchs laid 22% more eggs on sentinel milkweed plants in mixed-species plots with no effect of plant diversity on monarch survival. We also found higher natural enemy richness, wasp, and predatory bug abundance in the mixed-species plots and this did not translate to higher biological control rates. Our results provide more evidence that plant selection and habitat design are important for monarch conservation.

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 Balancing Disturbance and Conservation in Agroecosystems to Improve Biological Control

2020 ◽  
Vol 65 (1) ◽  
pp. 81-100 ◽  
Author(s):  
John F. Tooker ◽  
Matthew E. O'Neal ◽  
Cesar Rodriguez-Saona
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Crop Production ◽  
Agricultural Intensification ◽  
Conservation Practices ◽  
Insect Outbreaks ◽  
Top Down ◽  
Crop Fields ◽  
Pest Outbreaks

Disturbances associated with agricultural intensification reduce our ability to achieve sustainable crop production. These disturbances stem from crop-management tactics and can leave crop fields more vulnerable to insect outbreaks, in part because natural-enemy communities often tend to be more susceptible to disturbance than herbivorous pests. Recent research has explored practices that conserve natural-enemy communities and reduce pest outbreaks, revealing that different components of agroecosystems can influence natural-enemy populations. In this review, we consider a range of disturbances that influence pest control provided by natural enemies and how conservation practices can mitigate or counteract disturbance. We use four case studies to illustrate how conservation and disturbance mitigation increase the potential for biological control and provide co-benefits for the broader agroecosystem. To facilitate the adoption of conservation practices that improve top-down control across significant areas of the landscape, these practices will need to provide multifunctional benefits, but should be implemented with natural enemies explicitly in mind.

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.

scholarly journals Opposite effects of daytime and nighttime warming on top-down control of plant diversity

Ecology ◽  
2017 ◽  
Vol 99 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Brandon T. Barton ◽  
Oswald J. Schmitz
Keyword(s):  
Plant Diversity ◽  
Top Down ◽  
Nighttime Warming

scholarly journals Litter decomposition driven by soil fauna, plant diversity and soil management in urban gardens

2019 ◽  
Vol 658 ◽  
pp. 1614-1629 ◽  
Author(s):  
Simon Tresch ◽  
David Frey ◽  
Renée-Claire Le Bayon ◽  
Andrea Zanetta ◽  
Frank Rasche ◽  
...  
Keyword(s):  
Litter Decomposition ◽  
Plant Diversity ◽  
Soil Fauna ◽  
Soil Management ◽  
Urban Gardens

scholarly journals Methyl Salicylate Fails to Enhance Arthropod Predator Abundance or Predator to Pest Ratios in Cotton

2021 ◽  
Author(s):  
Steven E Naranjo ◽  
James R Hagler ◽  
John A Byers
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Methyl Salicylate ◽  
Production Systems ◽  
Control Function ◽  
Conservation Biological Control ◽  
Cotton Production ◽  
Control Activity ◽  
Synthetic Chemicals

Abstract Conservation biological control is a fundamental tactic in integrated pest management (IPM). Greater biological control services can be achieved by enhancing agroecosystems to be more favorable to the presence, survival, and growth of natural enemy populations. One approach that has been tested in numerous agricultural systems is the deployment of synthetic chemicals that mimic those produced by the plant when under attack by pests. These signals may attract arthropod natural enemies to crop habitats and thus potentially improve biological control activity locally. A 2-yr field study was conducted in the cotton agroecosystem to evaluate the potential of synthetic methyl salicylate (MeSA) to attract native arthropod natural enemies and to enhance biological control services on two key pests. Slow-release packets of MeSA were deployed in replicated cotton plots season long. The abundance of multiple taxa of natural enemies and two major pests were monitored weekly by several sampling methods. The deployment of MeSA failed to increase natural enemy abundance and pest densities did not decline. Predator to prey ratios, used as a proxy to estimate biological control function, also largely failed to increase with MeSA deployment. One exception was a season-long increase in the ratio of Orius tristicolor (White) (Hemiptera: Anthocoridae) to Bemisia argentifolii Bellows and Perring (= Bemisia tabaci MEAM1) (Hemiptera: Aleyrodidae) adults within the context of biological control informed action thresholds. Overall results suggest that MeSA would not likely enhance conservation biological control by the natural enemy community typical of U.S. western cotton production systems.

scholarly journals Species ethnobotanical values rather than regional species pool determine plant diversity in agroforestry systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel K. N’Woueni ◽  
Orou G. Gaoue
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Plant Diversity ◽  
Agroforestry Systems ◽  
Natural Vegetation ◽  
Species Pool ◽  
Higher Plant ◽  
Natural Habitats ◽  
Natural Systems ◽  
Regional Species Pool

AbstractThe conversion of natural systems into farms and agroecosystems is the main cause of biodiversity loss. In human-dominated landscapes, understanding the interactions between agroforestry systems and adjacent natural vegetation is fundamental to developing sustainable agricultural systems. Species can move between these two systems with natural systems providing the regional pool of species that shape the agricultural values and conservation value of the agroforestry systems. We investigated the influence of neighboring natural habitats on traditional agroforestry systems in the buffer zone of Pendjari Biosphere Reserve in Benin to understand the contribution of regional processes on the quality of agroforestry systems. We expected that agroforestry parklands adjacent to natural vegetation with high species diversity will also have higher plant species diversity. We found no similarity in plant species composition between agroforestry systems and adjacent natural habitats. A small proportion of species in adjacent natural habitats were found in agroforestry systems. The proportion of shared species was not significantly influenced by plant diversity in adjacent natural habitats or the distance from the agroforestry systems to the natural adjacent habitat. However, plant diversity in agroforestry systems was strongly associated with site ethnobotanical values indicating that farmers act as a supplemental but severe environmental filter of the regional species pool. Our study suggests that promoting the plantation of plants with high ethnobotanical use-value is a potentially viable strategy for sustainable agriculture and ecological restoration in Biosphere reserves.

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