scholarly journals The behaviour of hoverfly larvae (Diptera, Syrphidae) lessens the effects of floral subsidy in agricultural landscapes

2016 ◽  
Author(s):  
Elsa A. Laubertie ◽  
Steve D. Wratten ◽  
Alexandra Magro ◽  
Jean Louis RGM Hemptinne
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Laboratory Experiments ◽  
Landscape Management ◽  
Agricultural Landscapes ◽  
Floral Resources ◽  
Insect Behaviour ◽  
Resource Concentration ◽  
Conspecific Density ◽  
Set Up

Modern agricultural landscapes favour crop pests: herbivores benefit from resource concentration and/or the absence of natural enemies in large areas of intensively farmed fields interspersed by small fragments of natural or non-crop habitats. Conservation biological control (CBC) aims at increasing the functional diversity of agricultural landscapes to make them more hospitable to natural enemies, and less to herbivores. Although natural enemies readily respond to this management, very few studies assess if they succeed in effectively protecting crops. We set up a field experiment to study if an ecological infrastructure varying in size and consisting of the provision of floral resources at the centre of lettuce plots would influence the number of eggs laid by hoverflies, and ultimately the control of lettuce aphids. We found that the hoverfly females lay more eggs in the plots with the larger flower resource compared to the control. However, this response had no impact on the abundance of aphids on the lettuces. We designed two laboratory experiments to understand this absence of response. We found mutual interference between hoverfly larvae, and suggest it may undermine the biological control of aphids. This mismatch between landscape management and the response of hoverflies indicates CBC should take into account insect behaviour, particularly their response to conspecific density, additionally to landscape ecology.

scholarly journals The effect of within-crop habitat manipulations on the conservation biological control of aphids in field-grown lettuce

2011 ◽  
Vol 101 (6) ◽  
pp. 623-631 ◽  
Author(s):  
D.J. Skirvin ◽  
L. Kravar-Garde ◽  
K. Reynolds ◽  
C. Wright ◽  
A. Mead
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Floral Resources ◽  
Cereal Crops ◽  
Field Crops ◽  
Natural Regulation ◽  
Wildflower Strips ◽  
Natural Pest Regulation ◽  
The Impact ◽  
Regulation Changes

AbstractWithin-crop habitat manipulations have the potential to increase the biological control of pests in horticultural field crops. Wildflower strips have been shown to increase the abundance of natural enemies, but there is little evidence to date of an impact on pest populations. The aim of this study was to determine whether within-crop wildflower strips can increase the natural regulation of pests in horticultural field crops. Aphid numbers in plots of lettuce grown adjacent to wildflower strips were compared with those in plots grown in the absence of wildflowers. The presence of wildflower strips led to a decrease in aphid numbers on adjacent lettuce plants during June and July, but had less impact in August and September. The decrease in aphid numbers was greatest close to the wildflower strips and, the decrease in aphid numbers declined with increasing distance from the wildflower strips, with little effect at a distance of ten metres. The main natural enemies found in the crop were those that dispersed aerially, which is consistent with data from previous studies on cereal crops. Analysis and interpretation of natural enemy numbers was difficult due to low recovery of natural enemies, and the numbers appeared to follow changes in aphid abundance rather than being directly linked to the presence of wildflower strips. Cutting the wildflower strips, to remove floral resources, had no impact on the reduction in aphid numbers achieved during June and July, but decreased the effect of the wildflower strips during August and September. The results suggest that wildflower strips can lead to increased natural regulation of pest aphids in outdoor lettuce crops, but more research is required to determine how this is mediated by natural enemies and how the impact of wildflower strips on natural pest regulation changes during the growing season.

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 Density-dependent regulation in a weed Bidens sulphurea (Cav.) Sch. Bip. (Asteraceae)

2017 ◽  
Vol 2 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Natália De Freitas Medeiros ◽  
Diana Pacheco Seixas ◽  
Janaina Correia Batista ◽  
Wanessa Rejane Almeida ◽  
Jean Carlos Santos
Keyword(s):  
Biological Control ◽  
Invasive Species ◽  
Intraspecific Competition ◽  
Stem Height ◽  
Weed Species ◽  
Density Dependent ◽  
Conspecific Density ◽  
The Difference ◽  
Set Up ◽  
Over Time

The density effects on performance of a weed Bidens sulphurea (Asteraceae) were evaluated experimentally. There are very few studies available to improve the process of density-dependent to invasive species. It was used an experimental set-up in which the population of this weed species is partitioned into different density groups (1, 2, 4 and eight plants per pot) based on local conspecific density to investigate density-based population strategies. The difference between the greatest and the lowest density (8 and 1 plant per pot) was considerably high, around 41%, regarding the variables measured (stem height and diameter, leaf number and size). Plants at higher densities have become taller and thinner as a consequence of intraspecific competition. Therefore, the results suggest that the responses of B. sulphurea in dense populations can affect the persistence of population over time. These results may be useful in the future for the biological control of this species..

scholarly journals How Effective Is Conservation Biological Control in Regulating Insect Pest Populations in Organic Crop Production Systems?

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 744
Author(s):  
Raymond A. Cloyd
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Crop Production ◽  
Scientific Literature ◽  
Production Systems ◽  
Insect Pest ◽  
Conservation Biological Control ◽  
Flowering Plants ◽  
Floral Resources ◽  
Organic Crop Production

Organic crop production systems are designed to enhance or preserve the presence of natural enemies, including parasitoids and predators, by means of conservation biological control, which involves providing environments and habitats that sustain natural enemy assemblages. Conservation biological control can be accomplished by providing flowering plants (floral resources) that will attract and retain natural enemies. Natural enemies, in turn, will regulate existing insect pest populations to levels that minimize plant damage. However, evidence is not consistent, based on the scientific literature, that providing natural enemies with flowering plants will result in an abundance of natural enemies sufficient to regulate insect pest populations below economically damaging levels. The reason that conservation biological control has not been found to sufficiently regulate insect pest populations in organic crop production systems across the scientific literature is associated with complex interactions related to intraguild predation, the emission of plant volatiles, weed diversity, and climate and ecosystem resources across locations where studies have been conducted.

Screening Drought-Tolerant Native Plants for Attractiveness to Arthropod Natural Enemies in the U.S. Great Lakes Region

2019 ◽  
Author(s):  
Daniel R Gibson ◽  
Logan Rowe ◽  
Rufus Isaacs ◽  
Douglas A Landis
Keyword(s):  
Great Lakes ◽  
Plant Species ◽  
Natural Enemies ◽  
Native Species ◽  
Habitat Management ◽  
Echinacea Purpurea ◽  
Agricultural Landscapes ◽  
Floral Resources ◽  
Great Lakes Region ◽  
Monarda Fistulosa

Abstract Arthropods provide a variety of critical ecosystem services in agricultural landscapes; however, agricultural intensification can reduce insect abundance and diversity. Designing and managing habitats to enhance beneficial insects requires the identification of effective insectary plants that attract natural enemies and provide floral resources. We tested the attractiveness of 54 plant species with tolerance to dry soils, contrasting perennial forbs and shrubs native to the Great Lakes region to selected non-native species in three common garden experiments in Michigan during 2015–2016. Overall, we found 32 species that attracted significantly more natural enemies than associated controls. Among these, Achillea millefolium and Solidago juncea were consistently among the most attractive plants at all three sites, followed by Solidago speciosa, Coreopsis tripteris, Solidago nemoralis, Pycnanthemum pilosum, and Symphyotrichum oolantangiense. Species which attracted significantly more natural enemies at two sites included: Asclepias syriaca, Asclepias tuberosa, Monarda fistulosa, Oligoneuron rigidum, Pycnanthemum virginianum, Dasiphora fruticosa, Ratibida pinnata, Asclepias verticillata, Monarda punctata, Echinacea purpurea, Helianthus occidentalis, Silphium integrifolium, Silphium terebinthinaceum, Helianthus strumosus, and Symphyotrichum sericeum. Two non-native species, Lotus corniculatus, and Centaurea stoebe, were also attractive at multiple sites but less so than co-blooming native species. Parasitic Hymenoptera were the most abundant natural enemies, followed by predatory Coleoptera and Hemiptera, while Hemiptera (Aphidae, Miridae, and Tingidae) were the most abundant herbivores. Collectively, these plant species can provide floral resources over the entire growing season and should be considered as potential insectary plants in future habitat management efforts.

Yellow Brazilian Pepper-tree Leaf Galler (suggested common name) Calophya latiforceps Burckhardt (Insecta: Hemiptera: Calophyidae: Calophyinae)

EDIS ◽  
2017 ◽  
Vol 2017 (6) ◽  
Author(s):  
James P. Cuda ◽  
Patricia Prade ◽  
Carey R. Minteer-Killian
Keyword(s):  
Biological Control ◽  
North America ◽  
Natural Enemies ◽  
Host Plants ◽  
Classical Biological Control ◽  
Biological Control Agents ◽  
Pepper Tree ◽  
Brazilian Pepper ◽  
Close Relatives ◽  
Tree Leaf

In the late 1970s, Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), was targeted for classical biological control in Florida because its invasive properties (see Host Plants) are consistent with escape from natural enemies (Williams 1954), and there are no native Schinus spp. in North America. The lack of native close relatives should minimize the risk of damage to non-target plants from introduced biological control agents (Pemberton 2000). [...]

Investigation of nitrite pathways in sugar beet extraction

2014 ◽  
pp. 626-635 ◽  
Author(s):  
Florian Emerstorfer ◽  
Christer Bergwall ◽  
Walter Hein ◽  
Mats Bengtsson ◽  
John P. Jensen
Keyword(s):  
Sugar Beet ◽  
Laboratory Experiments ◽  
Ph Value ◽  
Full Scale ◽  
Chemical Effect ◽  
Spectrophotometric Detection ◽  
Sugar Factory ◽  
Chemical Effects ◽  
Set Up ◽  
Nitrate And Nitrite

The investigations presented in this work were carried out in order to further deepen the knowledge about nitrite pathways in the area of sugar beet extraction. The article consists of two parts with different experimental set-up: the first part focuses on laboratory trials in which the fate of nitrate and nitrite was studied in a so-called mini-fermenter. These trials were carried out using juice from the hot part of the cossette mixer of an Agrana sugar factory in Austria. In the experiments, two common sugar factory disinfectants were used in order to study microbial as well as microbial-chemical effects on nitrite formation and degradation caused by bacteria present in the juice. The trials demonstrated that the direct microbial effect (denitrification) on nitrite degradation is more pronounced than the indirect microbial-chemical effect coming from pH value decrease by these bacteria and subsequent nitrite loss. The second part describes the findings from laboratory experiments and full scale factory trials using a mobile laboratory set-up based on insulated stainless steel containers and spectrophotometric detection of nitrite in various factory juices. The trials were made at two Nordzucker factories located in Finland (factory A) and Sweden (factory B). The inhibiting effect of the two common sugar factory disinfectants on nitrite formation was evaluated in laboratory trials, whereas the full scale trials focused on one disinfectant. Other trials to evaluate potential contamination sources of thermophilic nitrite producing bacteria to the extraction system, reactivation of nitrite producing bacteria in raw juice and the effect of a pH gradient on bacterial nitrite activity in cossette mixer juice are also reported.

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