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See detailIdentification of flower functional traits affecting abundance of generalist predators in perennial multiple species wildflower strips
Hatt, Séverin ULiege; Uyttenbroeck, Roel; Lopes, Thomas et al

in Arthropod-Plant Interactions (2019)

In agricultural fields, wildflower strips can be sown to enhance conservation biological control of insect pests. However, issues remain regarding the composition of flower mixtures to effectively attract ... [more ▼]

In agricultural fields, wildflower strips can be sown to enhance conservation biological control of insect pests. However, issues remain regarding the composition of flower mixtures to effectively attract and support large communities of natural enemies. Trait-based approaches are promising for this purpose. In the present study, conducted in an agricultural field of Belgium in 2014 and 2015, 15 flower mixtures were considered to explore the relation between the abundance of trapped generalist predators (i.e. lacewings [Neuroptera: Chrysopidae], ladybeetles [Coleoptera: Coccinellidae] and hoverflies [Diptera: Syrphidae]) and the community-weighted means of seven flower traits. Through a redundancy analysis, it was found that the presence/absence of flower ultra-violet pattern and the morphology of the corolla (that determines the accessibility of floral resources) were the traits that significantly affected the abundance of the generalist predators in the flower mixtures. The ladybeetles Harmonia axyridis and Propylea quatuordecimpunctata as well as the lacewings Chrysoperla carnea were more abundant in mixtures with a high cover of flowers showing an ultra-violet pattern, while the opposite was observed for the ladybeetle Coccinella septempunctata. As for hoverflies, Episyrphus balteatus and Eupeodes corollae were more abundant in mixtures with a high cover of flowers with open nectar. These results bring new knowledge regarding how a range of natural enemy species reacts to flower cues in diversified plant communities and should help in elaborating flower mixtures that enhance conservation biological control. [less ▲]

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See detailIdentification of flower functional traits affecting abundance of generalist predators in perennial multiple species wildflower strips
Hatt, Séverin ULiege; Uytenbroeck, Roel; Lopes, thomas et al

in Arthropod-Plant Interactions (2019), 13

In agricultural fields, wildflower strips can be sown to enhance conservation biological control of insect pests. However, issues remain regarding the composition of flower mixtures to effectively attract ... [more ▼]

In agricultural fields, wildflower strips can be sown to enhance conservation biological control of insect pests. However, issues remain regarding the composition of flower mixtures to effectively attract and support large communities of natural enemies. Trait-based approaches are promising for this purpose. In the present study, conducted in an agricultural field of Belgium in 2014 and 2015, 15 flower mixtures were considered to explore the relation between the abundance of trapped generalist predators (i.e. lacewings [Neuroptera: Chrysopidae], ladybeetles [Coleoptera: Coccinellidae] and hoverflies [Diptera: Syrphidae]) and the community-weighted means of seven flower traits. Through a redundancy analysis, it was found that the presence/absence of flower ultra-violet pattern and the morphology of the corolla (that determines the accessibility of floral resources) were the traits that significantly affected the abundance of the generalist predators in the flower mixtures. The ladybeetles Harmonia axyridis and Propylea quatuordecimpunctata as well as the lacewings Chrysoperla carnea were more abundant in mixtures with a high cover of flowers showing an ultra-violet pattern, while the opposite was observed for the ladybeetle Coccinella septempunctata. As for hoverflies, Episyrphus balteatus and Eupeodes corollae were more abundant in mixtures with a high cover of flowers with open nectar. These results bring new knowledge regarding how a range of natural enemy species reacts to flower cues in diversified plant communities and should help in elaborating flower mixtures that enhance conservation biological control. [less ▲]

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See detailFlower Strips in Wheat Intercropping System: Effect on Pollinator Abundance and Diversity in Belgium
Amy, Clara ULiege; Noël, Grégoire ULiege; Hatt, Séverin ULiege et al

in Insects (2018), 9(3), 114

The decline of pollinators in agricultural areas has been observed for some decades, this being partly due to landscape simplification in intensive agrosystems. Diversifying agricultural landscapes by ... [more ▼]

The decline of pollinators in agricultural areas has been observed for some decades, this being partly due to landscape simplification in intensive agrosystems. Diversifying agricultural landscapes by sowing flower strips within fields could reduce these adverse effects on biodiversity. In this context, the study presented here aimed at assessing and comparing the abundance and diversity of bees (Hymenoptera: Anthophila) and hoverflies (Diptera: Syrphidae) found and visiting flowers in three types of flower strips in Belgium: (i) a mixture of 11 wild flowers, (ii) a monofloral strip of Dimorphoteca pluvialis (Asteraceae) and (iii) a monofloral strip of Camelina sativa (Brassicaceae), where the last two are considered to be intercrops since they are valuable on the market, all sown within a field of winter wheat (Triticum aestivum L.). Pollinators were captured with pan traps and by netting in standardised transects from May to July 2017. One-thousand one-hundred and eighty-four individuals belonging to 43 bee species and 18 hoverfly species were collected. Significant differences in hoverfly diversity were found between the different flower strips. The multifloral treatment supported a greater diversity of syrphid species. Various pollinator species visited the different flowers composing the mixture and also D. pluvialis. The pollinator community proved to be predominantly generalist, with the exception of an oligolectic species in Belgium, Andrena nitidiuscula. Moreover, the three tested flower strips were effective in attracting hoverflies, among them natural enemies of insect pests. This study opens new perspectives in the design of intercropping systems with flower strips towards the design of sustainable agro-ecosystems. Improving economic profitability of sowing flower strips could encourage farmers to diversify their agricultural systems and foster conservation biology strategies. [less ▲]

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See detailPerennial wildflower strips to enhance natural enemies of insect pests in Belgium
Hatt, Séverin ULiege; Monty, Arnaud ULiege; Chen, Julian et al

Conference (2018, May 14)

Increasing plant diversity at the local scale is expected to enhance conservation biological control of insect pests. To test this hypothesis, we sowed perennial wildflower strips within a wheat field and ... [more ▼]

Increasing plant diversity at the local scale is expected to enhance conservation biological control of insect pests. To test this hypothesis, we sowed perennial wildflower strips within a wheat field and found that hoverflies (Diptera: Syrphidae) were more abundant and aphids (Hemiptera: Aphididae) were reduced in wheat in between wildflower strips compared to adjacent monocultures. However, wildflower strips did not affect the other natural enemies, i.e. ladybeetles (Coleoptera: Coccinellidae), lacewings (Neuroptera: Chrysopidae) and Hymenopteran parasitoids. We then compared the abundance and diversity of these natural enemies in five flower mixtures that were different in their functional diversity based on seven plant traits. No significant effect of functional diversity was found. We hypothesised that the presence of some attractive flower species in the mixtures affected the spread of insects in the field. Finally through an RDA analysis, we identified that visual traits (colour, ultra-violet reflectance) and the shape of the corolla are the flower traits that significantly affect the abundance, in wildflower strips, of the wasps that parasitize oilseed rape beetles. This research highlight that perennial wildflower strips can enhance conservation biological control but understanding the interactions between insects and flower traits in fields is needed to compose flower mixtures that support a diversity of natural enemies. [less ▲]

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See detailSlow releaser of Methyl Salicylate can reduce insecticides for aphid control in the wheat field
Xu, Qingxuan; Xie, Lanfen; Hatt, Séverin ULiege et al

Conference (2018, May 14)

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See detailAromatic plants in East-Asia to enhance natural enemies towards biological control of insect pests. A review
Hatt, Séverin ULiege; Xu, Qingxuan; Francis, Frédéric ULiege et al

Poster (2018, May)

Introducing flowering plants in fields may attract and benefit predators and parasitoids of insect pests and potentially enhance biological control when associated with crops. Through a vote counting ... [more ▼]

Introducing flowering plants in fields may attract and benefit predators and parasitoids of insect pests and potentially enhance biological control when associated with crops. Through a vote counting analysis, the present review evaluates whether aromatic plants of East Asia could be used in this purpose. Through a systematic search of the scientific literature, we identified 64 papers published worldwide considering 32 aromatic plant species. We found a significant number of studies reporting that Apiaceae aromatic plants (Anethumgraveolens L., Coriandrumsativum L., Foeniculumvulgare L.) attract and benefit (in terms of longevity and/or fecundity) insect predators. Contrasting results were found for parasitoids, as well as with plant species from other families (mostly Asteraceae and Lamiaceae). Functional traits of plants (corolla shape, colour, volatiles) and of insects (mouthparts mainly) were considered to discuss these results. Additionally, we have not found a significant number of studies reporting an enhancement of biological control in crop or fruit trees cultivated adjacent to aromatic plants. However, the number of studies was limited, suggesting a need for further field-based research. Still, the retrieved studies highlight a recent interest for sowing aromatic plants in fields and orchards towards biological control of insect pests in East Asia and especially in China. [less ▲]

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See detailEffect of flower traits and hosts on the abundance of parasitoids in perennial multiple species wildflower strips sown within oilseed rape (Brassica napus) crops
Hatt, Séverin ULiege; Uyttenbroeck, Roel ULiege; Chevalier Mendes Lopes, Thomas et al

in Arthropod-Plant Interactions (2018)

Reducing the use of insecticides is an important issue for agriculture today. Sowing wildflower strips along field margins or within crops represents a promising tool to support natural enemy populations ... [more ▼]

Reducing the use of insecticides is an important issue for agriculture today. Sowing wildflower strips along field margins or within crops represents a promising tool to support natural enemy populations in agricultural landscapes and, thus, enhance conservation biological control. However, it is important to sow appropriate flower species that attract natural enemies efficiently. The presence of prey and hosts may also guide natural enemies to wildflower strips, potentially preventing them from migrating into adjacent crops. Here, we assessed how seven flower traits, along with the abundance of pollen beetles (Meligethes spp., Coleoptera: Nitidulidae) and true weevils (Ceutorhynchus spp., Coleoptera: Curculionidae), affect the density of parasitoids of these two coleopterans in wildflower strips sown in an oilseed rape field in Gembloux (Belgium). Only flower traits, not host (i.e. pollen beetles and true weevils) abundance, significantly affected the density of parasitoids. Flower colour, ultraviolet reflectance and nectar availability were the main drivers affecting parasitoids. These results demonstrate how parasitoids of oilseed rape pests react to flower cues under field conditions. Similar analyses on the pests and natural enemies of other crops are expected to help to develop perennial flower mixtures able to enhance biological control throughout a rotation system. [less ▲]

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See detailSpatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective
Hatt, Séverin ULiege; Boeraeve, Fanny ULiege; Artru, Sidonie ULiege et al

in Science of the Total Environment (2018), 621

Spatial diversification of crop and non-crop habitats in farming systems is promising for enhancing natural regulation of insect pests. Nevertheless, results from recent syntheses show variable effects ... [more ▼]

Spatial diversification of crop and non-crop habitats in farming systems is promising for enhancing natural regulation of insect pests. Nevertheless, results from recent syntheses show variable effects. One explanation is that the abundance and diversity of pests and natural enemies are affected by the composition, design and management of crop and non-crop habitats. Moreover, interactions between both local and landscape elements and practices carried out at different spatial scales may affect the regulation of insect pests. Hence, research is being conducted to understand these interdependencies. However, insects are not the only pests and pests are not the only elements to regulate in agroecosystems. Broadening the scope could allow addressing multiple issues simultaneously, but also solving them together by enhancing synergies. Indeed, spatial diversification of crop and non-crop habitats can allow addressing the issues of weeds and pathogens, along with being beneficial to several other regulating services like pollination, soil conservation and nutrient cycling. Although calls rise to develop multifunctional landscapes that optimize the delivery of multiple ecosystem services, it still represents a scientific challenge today. Enhancing interdisciplinarity in research institutions and building interrelations between scientists and stakeholders may help reach this goal. Despite obstacles, positive results from research based on such innovative approaches are encouraging for engaging science in this path. Hence, the aim of the present paper is to offer an update on these issues by exploring the most recent findings and discussing these results to highlight needs for future research. [less ▲]

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See detailA push–pull strategy to control aphids combines intercropping with semiochemical releases
Xu, Qingxuan ULiege; Hatt, Séverin ULiege; Chevalier Mendes Lopes, Thomas ULiege et al

in Journal of Pest Science (2018), 91

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have ... [more ▼]

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining both strategies can be an interesting way to maximize pest control. In this work, a 2-year setup involving wheat–pea strip intercropping combined with the release of E-b-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repel aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with the intercropping. The abundance of aphids was significantly decreased, while hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of the aphid-parasitism rate [mummies/(aphids + mummies)] was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides. [less ▲]

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See detailCombining E-β-farnesene and methyl salicylate release with wheat-pea intercropping enhances biological control of aphids in North China
Xu, Qingxuan; Hatt, Séverin ULiege; Han, Zongli et al

in Biocontrol Science and Technology (2018), 28(9), 883894

Combining intercropping with the release of semiochemicals may strengthen biological control of aphids as a push-pull strategy that simultaneously repels aphids and attracts their natural enemies. This ... [more ▼]

Combining intercropping with the release of semiochemicals may strengthen biological control of aphids as a push-pull strategy that simultaneously repels aphids and attracts their natural enemies. This hypothesis was tested in the Henan Province of China in 2016 where aphids, their natural enemies and mummies were trapped and observed on crops in three treatments: wheat-pea strip intercropping solely (control), intercropping combined with the release of E-β-farnesene (EBF) and intercropping combined with the release of methyl salicylate (MeSA). Each treatment was repeated four times. The abundance of aphids throughout the growing season (9 weeks between March and May) was significantly decreased and the abundance of natural enemies and mummies were significantly increased in treatments with releases of semiochemicals compared to intercropping solely. The effect was stronger with MeSA than with EBF on the control of Rhopalosiphum padi and pea aphids as well as on the attraction of lacewings and hoverflies. Indeed, lacewings and hoverflies were on average twice more numerous in MeSA than in the other treatments. These results show that combining wheat-pea intercropping with the release of EBF or MeSA can significantly reduce aphid density and attract their natural enemies and that this effect is strengthen with MeSA when compared to EBF. [less ▲]

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See detailSowing flower strips in a wheat field to enhance biological control of aphids and support pollinators
Amy, Clara ULiege; Brigode, Mélanie ULiege; Hatt, Séverin ULiege et al

Poster (2017, November 14)

Insect pests are responsible, among other factors, for reducing the productivity of crops. While chemical insecticides used to control them cause harmful effects on human health and the environment ... [more ▼]

Insect pests are responsible, among other factors, for reducing the productivity of crops. While chemical insecticides used to control them cause harmful effects on human health and the environment, conservation biological control, i.e. managing habitats in agricultural landscapes to support pest natural enemies, turns out to be a promising approach. Moreover, the decline of pollinators in agricultural areas is observed since a few decades, being partly due to the intensification of agriculture which homogenizes and degrades agricultural landscape. To reduce the detrimental effects of agricultural intensification on biodiversity, ecosystem functioning and ecosystem services, farmers have the opportunity to adopt agri-environmental measures. Among them, the establishment of flower strips, with a recognized interest in biological control and the conservation of pollinators, is proposed. However, their establishment is not systematically efficient and profitable for the farmers. Adapting mixture composition to farmer’s need may encourage their adoption. Thus, the research project has a double goals (i) to provide intercropping flower strips for promoting the attraction of beneficial insects against pests and for promoting pollinators diversity; and (ii) to suggests diversification of farm income by planting monospecific oilseed flower strips. [less ▲]

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See detailIncreasing plant functional diversity is not the key for supporting pollinators in wildflower strips
Uyttenbroeck, Roel ULiege; Piqueray, Julien; Hatt, Séverin ULiege et al

in Agriculture, Ecosystems and Environment (2017), 249

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown ... [more ▼]

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown a decline in species richness. Flower strips can be used to support pollinators in agro-ecosystems, however the question remains as to how their design can be optimized in order to best benefit pollinators. Increasing plant species diversity has been shown to be beneficial for pollinators, and it is often suggested that functional traits are driving this relationship. Therefore, increasing plant functional diversity could be a tool to support pollinator abundance and diversity. As experimental evidence on this relationship is scarce, we developed a field study with experimental sown flower strips with four functional diversity levels, based on multiple flower traits and with equal plant species richness. We monitored vegetation development, as well as the flower-visiting pollinator community and their interaction networks with flowers. We were able to create a functional diversity gradient while controlling for plant species richness and evenness. However, in contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. Network stability metrics showed no effect or negative relationships with functional diversity. We conclude that increasing functional diversity was not the key for supporting pollinators in wildflower strips. Our results also suggest that, for a constant amount of flower resources, increasing plant functional diversity and thus decreasing redundancy of potential pollinator feeding niches, decreases the amount of flower resources present per feeding niche. As pollinator species tended to have less overlap in their feeding niches in flower strips with increased functional diversity, this may lead to a reduction of flower resources available for pollinator species with a more specialized feeding niche. [less ▲]

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See detailLes savoirs paysans pour coordonner la conservation de la nature et l’agriculture - Piste pour une prise en compte renforcée des compétences des agriculteurs dans l’action agro-environnementale.
Brédart, David; Hatt, Séverin ULiege; Méhu, Marie et al

in Mille Lieux (2017), 7

Lors d’un travail de recherche, nous avons rencontré des agriculteurs de la zone limoneuse en Wallonie, un territoire de culture des plus productifs. Ces agriculteurs ont en commun d’avoir installé des ... [more ▼]

Lors d’un travail de recherche, nous avons rencontré des agriculteurs de la zone limoneuse en Wallonie, un territoire de culture des plus productifs. Ces agriculteurs ont en commun d’avoir installé des bandes aménagées en bordure de parcelles dans le cadre des méthodes agro-environnementales (MAEC - dispositifs de la Politique Agricole Commune visant à protéger l’environnement dans les espaces agricoles). Nous avons tenté de comprendre ce que sont et ce que pourraient devenir les bandes aménagées pour ces agriculteurs. En effet, alors que de nombreux travaux se sont intéressés aux aspects techniques, notamment à la composition et à la gestion des mélanges semés, peu d’attention a été portée aux agriculteurs et à la façon dont ils intègrent ces mélanges dans leur pratique. Nous explorons, à travers notre analyse, la possibilité d’une co-construction des MAEC avec les agriculteurs pour une action agro-environnementale pertinente aussi du point de vue de la production agricole. [less ▲]

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See detailEffects of wildflower strips and an adjacent forest on aphids and their natural enemies in a pea field
Hatt, Séverin ULiege; Mouchon, Pierre; Chevalier Mendes Lopes, Thomas ULiege et al

in Insects (2017), 8(3), 99

Landscape diversification is a key element for the development of sustainable agriculture. This study explores whether the implementation of habitats for pest natural enemies enhances conservation ... [more ▼]

Landscape diversification is a key element for the development of sustainable agriculture. This study explores whether the implementation of habitats for pest natural enemies enhances conservation biological control in an adjacent field. In the present study conducted in Gembloux (Belgium) in 2016, the effect of two different habitats (wildflower strips and a forest) and aphid abundance on the density of aphid natural enemies, mummified aphids and parasitism on pea plants was assessed through visual observations. The effect of the habitats on aphids was also evaluated. The habitats but not aphid density significantly affected hoverfly larvae, which were more abundant adjacent to wildflower strips than to the forest. The contrary was observed for ladybeetle adults, which were positively related with aphids but not affected by the adjacent habitats. The abundance of mummies and the parasitism rate were significantly affected by both the habitats and aphid density. They were both significantly enhanced adjacent to wildflower strips compared to the forest, but the total parasitism rate was low (<1%), questioning whether parasitoids could significantly control aphids on the pea crop. As for the aphids, their abundance was not significantly affected by the adjacent habitats. These results are discussed with respect to the potential of these habitats to provide overwintering sites and food resources for natural enemies, and thereby enhance conservation biological control. [less ▲]

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See detailSpatial diversification of agroecosystems towards biological control of insect pests: A focus on intercropping and wildflower strips
Hatt, Séverin ULiege

Doctoral thesis (2017)

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ... [more ▼]

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ecological processes within agroecosystems in order to enhance the delivery of ecosystem services towards reducing the use of external inputs – among others insecticides. For enhancing biological control of insect pests, a strategy is to spatially diversify agroecosystems at the field scale. Whereas increasing plant diversity could directly negatively affect pest development on the one hand (i.e. bottom-up effect), providing flowering features could allow the enhancement of natural enemies and their direct effect on pest populations on the other hand (i.e. top-down effect). The present thesis focused on intercropping (i.e. the cultivation of at least two crop species simultaneously in a same field) as a way to diversify crop habitat, and the sowing of wildflower strips as a non-crop feature. A systematic analysis of the literature revealed that, in most of studies, wheat (Triticum aestivum L.)-based intercropping allows a reduction of insect pests on crops, without necessarily favouring their natural enemies, compared to pure-stands. Besides, the provision of flowering resources, by for instance sowing wildflower strips, can attract and support flower visiting predators and parasitoids. Hence, in a first set of field experiments, combining the two tactics of increasing crop diversity and providing flowering resources was tested. First in China, wheat crop was associated with oilseed rape (Brassica napus L.), but it neither allowed reducing aphid (Hemiptera: Aphididae) abundance nor enhancing their natural enemies compared to pure stands. Instead, aphid density – independently from the treatments – affected natural enemy abundance, and interspecific relations between aphids and their natural enemies were observed. Second in Belgium, wildflower strips were sown within a wheat field, which led to a reduction of aphid density in wheat plots in between flowering features and an increase of aphidophagous hoverflies (Diptera: Syrphidae) compared to pure-stand wheat. Nevertheless, the presence of flowering strips did not affect the other natural enemies, i.e. lacewings (Neuroptera: Chrysopidae), ladybeetles (Coleoptera: Coccinellidae) and parasitoid wasps (Hymenoptera: Braconidae). Therefore, a second set of field experiments focussed on ways to compose mixtures of wild flowers attractive to a diversity of natural enemies. Flower functional traits were considered due to their effect on insect behaviour. First, the hypothesis that mixtures with high functional diversity attract and support a high abundance and diversity of aphid flower visiting predators was tested. This hypothesis was not verified. Instead, the high density in the plots of some flower species (especially the Asteraceae Leucanthemum vulgare Lam.) known to be attractive to flower visitors was supposed to have overwhelmed the effect of functional diversity. Second, a methodology was developed to identify which flower traits significantly affect natural enemy abundance – in this experiment parasitoids of oilseed rape beetle pests (i.e. Meligethes spp. [Coleoptera: Nitidulidae] and Ceutorhynchus spp. [Coleoptera: Curculionidae]) – in flower mixtures. Among seven traits, visual traits (i.e. colour, ultra-violet reflectance) and the one related to food availability (i.e. corolla morphology) were found to significantly affect parasitoid abundance. These results highlight that (i) increasing plant diversity at the field scale can – but not systematically – favour a reduction of insect pests, (ii) including flowering features can enhance some – but not all – of their natural enemies, and (iii) in order to compose flower mixes attractive to natural enemies, specific flower traits – rather than functional diversity at the mixture level – can be considered. These results are discussed in a broader perspective. Indeed, strategies to spatially diversify crop and non-crop habitats in agroecosystems are various, as well as the ways to compose, manage and design such habitats. Also, processes at larger scales than the field may be determinant. Moreover, insects are not the only pests, and pests are not the only biotic or abiotic elements that need to be regulated in agroecosystems. Controlling multiple pests simultaneously but also enhancing the provision of multiple regulating services represent challenges for future research in agriculture. [less ▲]

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See detailEffect of plant age and species on population growth of two Rhopalosiphum maidis (Fitch) lineages
Guo, Jianqin; Hatt, Séverin ULiege; Wang, Zhenying et al

in Communications in Agricultural and Applied Biological Sciences (2017, May), 82(2), 183-188

The corn leaf aphid Rhopalosiphum maidis (Fitch) can feed on various cereal crops and transmit viruses that may cause serious economic losses. To test the impact of host plant species and age on R. maidis ... [more ▼]

The corn leaf aphid Rhopalosiphum maidis (Fitch) can feed on various cereal crops and transmit viruses that may cause serious economic losses. To test the impact of host plant species and age on R. maidis, we identified the survival and reproduction rates of two R. maidis populations (Beijing and Mangshi) via a direct observation method in laboratory on 10 cm high maize seedlings (small maize), 50 cm high maize seedlings (high maize) and 10 cm high barley seedlings (barley). The Beijing (BJ) population performed significantly better than the Mangshi (MS) one on 50 cm high maize seedlings and barley seedlings, while both populations could not survive on maize seedlings in 10 cm height. As smaller maize seedlings were fatal to the corn leaf aphid, we hypothesized that it may be due to the secondary metabolites synthesized by maize seedlings and our results also give the implication for aphid control on maize which will be discussed. [less ▲]

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See detailNine facultative endosymbionts in aphids. A review
Guo, Jianqing ULiege; Hatt, Séverin ULiege; He, Kanglai et al

in Journal of Asia-Pacific Entomology (2017), 20

Aphids are frequently engaged in mutualistic associations with endosymbionts. Symbionts are bacterial or fungal microorganisms that can be obligate or facultative to aphids. Research showed facultative ... [more ▼]

Aphids are frequently engaged in mutualistic associations with endosymbionts. Symbionts are bacterial or fungal microorganisms that can be obligate or facultative to aphids. Research showed facultative (or secondary) symbionts have numerous effects on their host aphids such as resistance to heat shock, parasitoids and fungus etc., which may consequently promote a co-evolution between symbionts and hosts. However, this symbiotic relation may be affected by several factors, such as the ability of symbionts to spread from aphids to others within and across populations, and the cost of infections for hosts. Moreover, aphid-symbionts interactions may be affected by aphid living environment such as its host plant, the presence of natural enemies or the temperature. Here we firstly described the functions of nine facultative symbionts (Serratia symbiotica, Hamiltonella defensa, Regiella insecticola, Rickettsia, Rickettsiella, PAXS (pea aphid X-type symbiont), Spiroplasma, Wolbachia and Arsenophonus) studied in aphids one by one, and discussed the associations between these symbionts and aphids, plants and environment. We aim to have a better knowledge of the roles the facultative symbionts play in aphid biology, ecology and evolution, which we believe can provide new inspirations for aphid control. [less ▲]

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See detailDo flower mixtures with high functional diversity enhance aphid predators in wildflower strips?
Hatt, Séverin ULiege; Uyttenbroeck, Roel ULiege; Chevalier Mendes Lopes, Thomas ULiege et al

in European Journal of Entomology (2017), 114

Among semi-natural elements in agricultural landscapes, wildflower strips sown at field margins or within fields represent potential habitats for the natural enemies of insect pests. As insects are ... [more ▼]

Among semi-natural elements in agricultural landscapes, wildflower strips sown at field margins or within fields represent potential habitats for the natural enemies of insect pests. As insects are sensitive to a variety of flower traits, we hypothesised that mixtures with high functional diversity attract and support a higher abundance and species richness of aphid flower visiting predators compared to mixtures with low functional diversity. During a field experiment, repeated over two years (2014 and 2015) in Gembloux (Belgium), aphid predators (i.e., lacewings, ladybeetles and hoverflies) were pan-trapped in five sown flower mixtures (including a control mixture, with three replicates of each mixture) of low to high functional diversity based on seven traits (i.e., flower colour, ultra-violet reflectance and pattern, blooming start and duration, height and flower class, primarily based on corolla morphology). In both years, flower species in the sown mixtures (i.e., sown and spontaneous flowers) were listed, and the realised functional diversity of each plot was calculated. Over the two years, an increase in functional diversity did not result in an increase in the abundance and richness of aphid predators. Moreover, ladybeetles, representing the majority of trapped predators, were more abundant in mixtures with very low or intermediary functional diversity at sowing, especially in 2014. We hypothesise that certain flower species, which were abundant in certain mixtures (and not in those exhibiting the highest functional diversity), attracted predators and were sufficiently represented to support them. Our results present novel information that could be used to the development of flower mixtures that provide effective ecosystem services, such as pest control. [less ▲]

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See detailAntipredator response of aphids to ladybeetles: Effect of intercropping on aphid dispersal
Xu, Qingxuan; Hatt, Séverin ULiege; Lopes, Thomas et al

in Communications in Agricultural and Applied Biological Sciences (2017), 82(2), 215-225

Dispersal of viruses is intimately tied to their vectors. Aphids are known to invest in costly antipredator behavior when perceiving cues of predators. It is hypothesized that the absconding behavior of ... [more ▼]

Dispersal of viruses is intimately tied to their vectors. Aphids are known to invest in costly antipredator behavior when perceiving cues of predators. It is hypothesized that the absconding behavior of aphids in the presence of predators can increase virus spread in fields. Whereas most of the studies investigating this hypothesis were conducted in monoculture, we studied aphid antipredator behavior in intercropping with wheat (Triticum aestivum L.)-broad bean (Vicia faba L.) as a model. The bird cherry-oat aphid, Rhopalosiphum padi Linnaeus (Hemiptera: Aphididae), is an important vector of the barley yellow dwarf virus. The effects of two natural aphid enemies, adults and larvae of the seven-spot ladybeetle, Coccinella septempunctata Linneaus (Coleoptera: Coccinellidae), on R. padi dispersion was studied under laboratory conditions. Trays composed of 7 × 8 lines of plants were considered. In intercropping, one line of broadbean succeeded one line of wheat. Six treatments were compared: in both wheat monoculture and intercropping, aphids were introduced alone, with ladybeetle larvae or with ladybeetle adults. Aphids and predators were introduced on wheat tillers in the middle of the system (source line) and aphids were counted on every plant after two and 24 hours. Results show that the total number of aphids was higher in intercropping than monoculture in treatments without ladybeetles, while the contrary was observed in the presence of ladybeetle larvae. But after 24 hours, such differences were not observed anymore. However, in receptor lines (other lines than the source one), two hours after the experiment started, aphids were more abundant in monoculture than intercropping in the presence of ladybeetle adults and larvae and after 24 hours, it was still the case in the presence of predatory larvae. These results might be explained by the non-host plant chemical cues and the physical barrier that was broad-bean plants confusing R. padi when searching for their host plants after being dropped from wheat by predators (i.e. associational resistance). This study shows that intercropping can reduce the dispersal of aphids in the presence of predators, in fine potentially limiting virus dispersal, especially shortly after aphids colonize plants. [less ▲]

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