Factors involved in the aggregation of Harmonia axyridis Pallas

Conference (2012, May 22)

In order to survive cold winters, the invasive multicoloured Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) forms large aggregations in dwellings to overwinter. The factors ... [more ▼]

In order to survive cold winters, the invasive multicoloured Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) forms large aggregations in dwellings to overwinter. The factors involved in the selection of aggregation sites remain misunderstood. The work presented herein focussed on the study of the chemical compounds involved in this phenomenon. Chemical and behavioural analyses highlighted that long-chain hydrocarbons lead congeners towards aggregation sites and ensure the cohesion of the cluster. Subsequently, physical factors were investigated. We studied the influence of (1) the density of individuals and (2) the quality of available shelters on H. axyridis decision to settle and aggregate under shelters. A binary choice experiment conducted in laboratory showed that the multicoloured Asian ladybeetles present a permanent aggregative behaviour, even during non-wintering conditions. These experiments also highlighted the existence of social interactions between individuals. All these results contribute to improve knowledge of this behaviour in H. axyridis and could be used in the design of species-specific traps in order to control infestations in dwellings. [less ▲]

A Semiochemical Slow-release Formulation in a Biological Control Approach to Attract Hoverflies

in Journal of Environment and Ecology (2012), 3(1), 72-85

E-β-Farnesene, the alarm pheromone of many aphid species, and E-β-caryophyllene are considered as two sesquiterpenes attractive for aphid predators, among which Syrphidae species. Both compounds were ... [more ▼]

E-β-Farnesene, the alarm pheromone of many aphid species, and E-β-caryophyllene are considered as two sesquiterpenes attractive for aphid predators, among which Syrphidae species. Both compounds were formulated in alginate gel beads as slow-release devices in a biological control approach against aphids. Semiochemical diffusion from beads was studied in the laboratory according to abiotic parameters. Efficiency of formulations as hoverfly attractant was demonstrated in field experiments from June to August 2009. The diffusion of semiochemicals from alginate bead formulations was principally limited by high values (>85%) of relative humidity in the air. Temperature also impacts the release of volatile compounds. In field experiments, these two abiotic factors were supposed to highly condition the trapping of hoverflies. These field trappings demonstrated the efficiency of both semiochemical formulations compared to control (formulation without semiochemical) to catch females of Syrphidae during three months. [less ▲]

Identification and quantification of VOCs emitted by the roots of barley (Hordeum vulgare cv. Quench) aged from 21 days by headspace solid-phase microextraction coupled to gas chromatography (HS-SPME GC-MS)

Poster (2012, February 10)

Improvement of Ylang-ylang essential oil characterization by GC×GC-TOFMS.

Poster (2012, February 02)

Fast-GC quantifacation of harmonine, the major defense alkaloid of the multicolored Asian ladybird Harmonia axyridis (Pallas)

in American Journal of Analytical Chemistry (2012), 3

These last few years the multicolored Asian ladybird, Harmonia axyridis (Pallas), previously introduced in Europe and North America as a biological control agent, has swiftly spread out on those ... [more ▼]

These last few years the multicolored Asian ladybird, Harmonia axyridis (Pallas), previously introduced in Europe and North America as a biological control agent, has swiftly spread out on those territories and turns out to be a pest in several ways. In order to improve understanding of several key points of the biology of this ladybird, a novel fast-GC method of quantification of harmonine, the main defense alkaloid of H. axyridis, has been designed and validated using the accuracy profile concept for concentrations ranging from 13 to 264 µg/individual. This method allows quantifying harmonine in a single insect with a maximal error risk of 20%. For ladybirds collected in spring, mean harmonine concentration observed was 106.6 µg/individual with a very high standard deviation of 80.2 µg/individual, which can easily be explained by the strong asymmetry of the results distribution. Males and females seem equally chemically protected as the harmonine concentration did not significantly differ between sexes. This method is currently used to improve our comprehension of several key points of H. axyridis biology including aggregation behavior and aposematism. [less ▲]

Variations in the essential oils from ylang-ylang (Cananga odorata [Lam.] Hook f. & Thomson forma genuina) in the Western Indian Ocean islands

in Flavour and Fragrance Journal (2012), 27(5), 356-366

Ylang-ylang essential oil is an important rawmaterial for the fragrance industry. Despite its economic importance, to the best of our knowledge, no study has yet been undertaken to assess the chemical ... [more ▼]

Ylang-ylang essential oil is an important rawmaterial for the fragrance industry. Despite its economic importance, to the best of our knowledge, no study has yet been undertaken to assess the chemical polymorphism of the different production areas. This underestimated variability is an interesting source of raw material for perfumers. That is why the variation in the chemical composition of four fractions of the essential oils extracted from Cananga odorata, grown in four locations Grande Comore, Mayotte, Nossi Bé and Ambanja, was studied. A total of 119 compounds, representing 85.7–96.4%of the total essential oil composition, were identified using gas chromatography–mass spectrometry and quantified by gas chromatography with a flame ionization detector. Thirty-two compounds previously unreported in ylang-ylang essential oil were identified. The distinction between the Comoros and Madagascar groups wasmade on the basis of the chemical classes. It was possible to significantly distinguish the Grande Comore and Mayotte essential oil samples, as well as the Ambanja and Nossi Bé essential oil samples, on the basis of their main compounds. The aromatic compounds profile for the origin of each essential oil fraction was established. Regression trees were built, allowing the provenance of the essential oils prepared at the laboratory level to be easily differentiated on the basis of a limited number of major compounds. [less ▲]

Chemical Composition and Antioxidant Activity of Essential Oil of Ocimum basilicum Leaves from the Northern Region of Algeria

in Topclass Journal of Herbal Medicine (2012), 1(2), 53-58

Ocimum basilicum essential oil (Algerian species), which is extracted from dried leaves with an output of 1.98 ± 0.01%, is yellow pale. Its chemical composition has been investigated by GC/MS and GC/FID ... [more ▼]

Ocimum basilicum essential oil (Algerian species), which is extracted from dried leaves with an output of 1.98 ± 0.01%, is yellow pale. Its chemical composition has been investigated by GC/MS and GC/FID. Fourty compounds have been identified accounting for 97.4%. The major compounds were: Linalool (32.83%), linalyl acetate (16%), elemol (7.44%), geranyl acetate (6.18%), myrcene (6.12%), allo-ocimene (5.02%), α-terpineol (4.9%), (E)-β-ocimene (3.68%) and neryl acetate (3.45%). O. basilicum essential oil was screened for its in vitro antioxidant activity using DPPH assay. The results showed that the concentration of the essential oil needed to scavenge 50% of DPPH, was 83.54 mg/ml lower than that of vitamin E (22.0 mg/ml) and therefore acts as a natural antioxidant agent. [less ▲]

Fast-GC quantification of harmonine, the major defense alkaloid of the multicolored asian ladybird Harmonia axyridis (Pallas)

in American Journal of Analytical Chemistry (2012), 3

The Essential Oils of Origanum majorana L. and Origanum floribundum Munby in Algeria

in Journal of Essential Oil-Bearing Plants [=JEOBP] (2012), 15(3), 497-502

The constituents of essential oils isolated by hydrodistillation of the overground parts of Origanum majorana and Origanum floribundum from Algeria were examined by GC and GC-MS. A total of thirty eight ... [more ▼]

The constituents of essential oils isolated by hydrodistillation of the overground parts of Origanum majorana and Origanum floribundum from Algeria were examined by GC and GC-MS. A total of thirty eight and thirty seven components were identified accounting for 93.3 % and 88.9 %, respectively, of the oils of O. majorana and O. floribundum. The oil of O. majorana (yield: 1.2 %) contained, as main components, β-caryophyllene (26.0 %), α-terpinolene (14.7 %), γ-terpinene (10.9 %) and sabinene (9.5 %). Major compounds in the volatile oil of O. floribundum (yield: 1.6 %) were γ-terpinene (34.1 %), p-cymene(27.6 %) and carvacrol (9.6 %). [less ▲]

Comment les insectes communiquent-ils au sein de l’ «écosystème-cadavre» ? L’écologie chimique des insectes nécrophages et nécrophiles

in Faunistic Entomology - Entomologie Faunistique (2012), 65

L’entomologie forensique est une discipline des sciences forensiques qui étudie les insectes et d’autres arthropodes dans un contexte médico-légal. Les insectes nécrophages et nécrophiles, principalement ... [more ▼]

L’entomologie forensique est une discipline des sciences forensiques qui étudie les insectes et d’autres arthropodes dans un contexte médico-légal. Les insectes nécrophages et nécrophiles, principalement des Diptères et des Coléoptères, sont fréquemment retrouvés au sein de l’écosystème-cadavre. Pour ces insectes, le cadavre est une ressource éphémère très riche qu’ils vont coloniser de manière plus ou moins prévisible. L’entomofaune des cadavres seraient attirées par les odeurs cadavériques émises par le corps en décomposition. A l’heure actuelle, la thanatochimie est encore peu étudiée et l’information disponible concernant les COVs émis après la mort est limitée. Grâce à l’utilisation des méthodes de chimie analytique (TDS)GC-MS, GCxGC-TOF-MS), la signature olfactive d’un cadavre peut être étudiée au cours du processus de décomposition. L’ « odeur de la mort » est constituée par un mélange de plus de cent composés organiques volatils qui évoluent au cours de la décomposition. Cependant, les sémiochimiques qui sont réellement attractifs pour les insectes nécrophages et/ou nécrophiles ne sont pas encore clairement identifiés. Les espèces pionnières pourraient être attirées par des COVs cadavériques. Toutefois, les espèces plus tardives pourraient aussi être attirées par d’autres types de sémiochimiques produits par les insectes sarcosaprophages eux-mêmes (par exemple : des asticots, des insectes nécrophages). Plusieurs techniques d’écologie chimique peuvent être utiles en vue d’investiguer le rôle des sémiochimiques cadavériques dans le comportement des insectes sarcosaprophages. Une meilleure compréhension de l’écologie chimique des insectes nécrophages/nécrophiles et la thanatochimie pourraient avoir de nombreuses applications en science forensique et plus particulièrement en entomologie forensique. [less ▲]