Application of semiochemical releasers and intercropping to control aphid and related virus in east China

Peer reviewe

Interactions of natural rhamnolpids produced by Pseudomonas aeruginosa with plant model membranes

It is well known that chemical pesticides have harmful effects on human health and environment. In this context, the interest for alternative products such as biopesticides is increasing. Among them, elicitors act on the plants by inducing systemic resistance against diseases caused by fungal, viral, bacterial agents and insects. Rhamnolipids are surface active molecules produced mainly by various strains of the bacterium Pseudomonas aeruginosa. These secondary metabolites are composed of one to three fatty acids with various chain lengths linked through a glycosidic bond to one or two rhamnose moieties. The fatty acids are linked together through an ester bond. These molecules have shown several biological activities including plant defense stimulation. It has been suggested that this elicitor activity could be related to an interaction of rhamnolipids with the lipid bilayer of the plant plasma membrane (PPM) and lead to its destabilization, which can activate the plant defense signaling pathways. In this context, interactions of two rhamnolipids (Rha-C10-C10 and Rha-Rha-C10-C10) with biomimetic membranes of PPM such as Langmuir monolayers and multilayers were investigated using biophysical and in silico approaches

Analysis of the interactions of natural elicitor rhamnolipids with plant plasma membranes by in silico methods

Rhamnolipids are surface active molecules produced mainly by various strains of the bacterium Pseudomonas aeruginosa. These secondary metabolites are composed of one to three fatty acids with various chain lengths linked through a glycosidic bond to one or two rhamnose moieties. The fatty acids are linked together through an ester bond. These molecules have shown several biological activities including plant defense stimulation. It has be suggested that this elicitor activity could be related to an interaction of rhamnolipids with the lipid bilayer of the plant plasma membrane (PPM) and lead to its destabilization, which can activate the plant defense signaling pathways. In this context, interactions of two rhamnolipids (Rha-C10-C10 and Rha-Rha-C10-C10) with membrane models and lipidic constituents of the PPM were investigated using in silico approaches. Most probable chemical structures of the rhamnolipids were determined using the STRUCTURE TREE procedure according to the molecule potential energy. The ability of these rhamnolipid structures to insert within the PPM was assessed using IMPALA simulations. IMPALA uses a membrane model in which phospholipids molecules are implicitly modeled by an empirical function and the membrane properties are modeled by energetic restraints. The ability of each rhamnolipid structure to form an assembly with several PPM constituents (phospholipid (PLPC), sterols (Sitosterol, Stigmasterol, Campesterol) and sphingolipids (GIPC, Glucosylceramide)) was calculated using the HYPERMATRIX procedure, which calculate and minimize the energies of interaction between all molecules of the complex until the lowest energy structure is reached.FIELD (Finding Interesting Elicitor LipiDs

Interactions of a potential plant elicitor mannolipid with plant model membranes

The use of chemical pesticides causes problems for human health and environment. In this context, there is an increasing interest for alternative products such as biopesticides. Among them, elicitors act on the plants by inducing systemic resistance against diseases caused by fungal, viral, bacterial agents and insects. The target of the elicitors is supposed to be the plant plasma membranes (PPM). The main mechanisms of interaction of many elicitors involve proteic receptors but lipid-based elicitors (LBE) may preferably interact with the lipidic fractions of PPM. However there is no detailed information at the molecular level on the PPM-LBE interactions. Our work is focused on a original synthetic LBE composed of a mannoside linked to a myristic acid. It has potential elicitor activities as shown by the assays on tobacco root cells. These activities could be related to its interaction with the lipidic phase of PPM. Since PPM are complex entities, the analyses of the PPM- molecule interactions are quite difficult. In this context, these interactions were carried out using biomimetic membranes of PPM such as Langmuir monolayers and multilayers. The effects of our molecule on these membranar systems were investigated by biophysical and in silico approaches.ARC-FIELD (Finding Interesting Elicitor LipiDs

Evaluation de la diversité des pucerons et de leurs ennemis naturels en cultures maraîchères dans l’est de la Chine

L’objet de cette étude, menée dans des champs de la province du Shandong, Chine, consistait à déterminer la diversité et l’abondance de pucerons et d’insectes auxiliaires aphidiphages en courgettes et en pommes de terre. L’inventaire des populations de pucerons et d’auxiliaires aphidiphages a été réalisé entre le 9 mai et le 13 juin 2011, à l’aide de pièges jaunes et d’observations sur plante. Au total, 53.206 individus ont été piégés et 35.144 observés. Les pucerons sont largement majoritaires et ils exercent une forte pression sur ces deux cultures en début de saison. Seules, deux espèces ont été identifiées sur plante, à savoir Aphis gossypii essentiellement sur courgette et Myzus persicae sur pomme de terre. Les coccinelles sont les prédateurs aphidiphages les plus abondants, notamment l’espèce Coccinella septempunctata pour les courgettes et Propylea japonica pour les pommes de terre, la première étant plus précoce que la deuxième. Peu de syrphes et de chrysopes ont été capturés. Les micro-hyménoptères apparaissent plus tard dans la saison. L’espèce Aphidius gifuensis représente la majorité des Braconidae capturés, tandis que la famille des Aphelinidae est majoritaire au sein des aphidiphages. Mots-clés: diversité, abondance, pucerons, aphidiphages, courgettes, pommes de terre. The aim of this study was to evaluate the diversity and abundance of aphids and aphidophagous beneficials in courgettes and potato fields in the Shandong province, East of China. The assessment of aphid and related beneficial populations was conducted between May 9th and June 13th, 2011, using yellow traps and in situ observations on plants. A total of 53,206 insects were trapped and 35,144 observed on the plants. Aphids widely predominated in the traps and exerted a strong pressure on both crops early in the season. Two main species were identified on the plants, namely Aphis gossypii on the courgettes and Myzus persicae on the potatoes. Ladybirds were the most abundant aphidophagous predators, especially Coccinella septempunctata on the courgettes and Propylea japonica on the potato fields, the first one being earlier than the second. Only few hoverflies and lacewings were captured. Microhymenoptera appeared later in the season. The Aphidius gifuensis species represented the majority of trapped Braconidae, while the family Aphelinidae contained the largest number of individuals in the aphidiphagous

New alternatives to chemical pesticides: deciphering the action mechanisms of lipid based plant elicitors via complementary biophysical and biological approaches.

Nowadays, many health and environmental problems are caused by the use of chemical pesticides. In this context, an increasing demand for alternative products such as biopesticides has been observed. Among biopesticides, elicitor molecules which are able to trigger immune defense responses in plants are one of the most promising options. Although numerous elicitors have been discovered, the mechanisms involved in the perception, by plants, of only a few molecules have been identified. These elicitors usually interact with proteic receptors but we have recently shown that they may also act on the lipid phase of the plasma membrane. This project first aims to improve our understanding of the molecular mechanisms involved in the recognition of specific lipid based elicitors (LBE). On that basis, the FIELD project will contribute to the design and the development of innovative compounds derived natural LBE. A multi-disciplinary approach, based on chemistry, bio-physics, bio-chemistry, and phytopathology will be followed by a consortium of different research groups from Gembloux Agro-Bio Tech in close collaboration with teams from foreign institutions.Projet ARC-FIEL

Evaluation of the diversity of aphids and their natural enemies in vegetable crops in eastern China

L’objet de cette étude, menée dans des champs de la province du Shandong, Chine, consistait à déterminer la diversité et l’abondance de pucerons et d’insectes auxiliaires aphidiphages en courgettes et en pommes de terre. L’inventaire des populations de pucerons et d’auxiliaires aphidiphages a été réalisé entre le 9 mai et le 13 juin 2011, à l’aide de pièges jaunes et d’observations sur plante. Au total, 53.206 individus ont été piégés et 35.144 observés. Les pucerons sont largement majoritaires et ils exercent une forte pression sur ces deux cultures en début de saison. Seules, deux espèces ont été identifiées sur plante, à savoir Aphis gossypii essentiellement sur courgette et Myzus persicae sur pomme de terre. Les coccinelles sont les prédateurs aphidiphages les plus abondants, notamment l’espèce Coccinella septempunctata pour les courgettes et Propylea japonica pour les pommes de terre, la première étant plus précoce que la deuxième. Peu de syrphes et de chrysopes ont été capturés. Les micro-hyménoptères apparaissent plus tard dans la saison. L’espèce Aphidius gifuensis représente la majorité des Braconidae capturés, tandis que la famille des Aphelinidae est majoritaire au sein des aphidiphages.The aim of this study was to evaluate the diversity and abundance of aphids and aphidophagous beneficials in courgettes and potato fields in the Shandong province, East of China. The assessment of aphid and related beneficial populations was conducted between May 9th and June 13th, 2011, using yellow traps and in situ observations on plants. A total of 53,206 insects were trapped and 35,144 observed on the plants. Aphids widely predominated in the traps and exerted a strong pressure on both crops early in the season. Two main species were identified on the plants, namely Aphis gossypii on the courgettes and Myzus persicae on the potatoes. Ladybirds were the most abundant aphidophagous predators, especially Coccinella septempunctata on the courgettes and Propylea japonica on the potato fields, the first one being earlier than the second. Only few hoverflies and lacewings were captured. Microhymenoptera appeared later in the season. The Aphidius gifuensis species represented the majority of trapped Braconidae, while the family Aphelinidae contained the largest number of individuals in the aphidiphagous.Projet Interuniversitaire Ciblé (PIC): "Développement et valorisation de nouvelles stratégies de lutte contre les ravageurs, vecteurs de maladies virales, en milieu rural dans la Province de Shandong (P.R. Chine)

Evaluation of the diversity of insect fauna in vegetable crops in eastern China

Dans le cadre de recherches visant à développer la lutte biologique en cultures maraîchères dans la province du Shandong en Chine, une surveillance des ravageurs et auxiliaires entomophages associés a été menée afin de déterminer les groupes d’insectes d’intérêt agronomique et de les comparer à la situation en Belgique. La diversité et l’abondance de l’entomofaune en culture de courgettes et de pommes de terre ont été évaluées entre le 9 mai et le 13 juin 2011, à l’aide de pièges jaunes et d’observations sur les plantes hôtes. Les insectes capturés ont tous été identifiés jusqu’au rang taxonomique de la famille. Les espèces de ravageurs ont fait l’objet d’une attention particulière. Au total, 36 466 et 34 806 insectes ont été capturés ou observés respectivement en cultures de courgettes et de pommes de terre. Dix ordres et une soixantaine de familles pour chaque culture ont été identifiés. Les pucerons sont largement majoritaires et exercent une forte pression sur ces deux cultures en début de saison. D’autres familles de ravageurs ont été identifiées mais aucune espèce spécifique de ces deux cultures et de la région investiguée ne figure parmi les collectes.Within the framework of research aimed at developing biological control in vegetable crops in Shandong province in China, a pest and associated auxiliary entomophagous insects monitoring was conducted to determine entomological groups of agricultural interest and compare them to the situation in Belgium. The diversity and abundance of the entomofauna were assessed in potato and zucchini fields between May 9th and June 13th, 2011, using yellow traps and in situ observations on host plants. A total of 36 466 and 34 806 insects were trapped or observed on the plants in zucchini and potato fields, respectively. Ten orders and more than sixty families in each crop were identified. Aphids widely predominated in the traps and exerted a strong pressure on both crops early in the season. Other families of pests have been identified but no specific pest of these two crops and the investigated region is among the collections.Projet Interuniversitaire Ciblé (PIC): "Développement et valorisation de nouvelles stratégies de lutte contre les ravageurs, vecteurs de maladies virales, en milieu rural dans la Province de Shandong (P.R. Chine)