Chemical Heterogeneity in Inbred European Population of the Invasive Hornet Vespa velutina nigrithorax.

Invasive social insect populations that have been introduced to a new environment through a limited number of introduction events generally exhibit reduced variability in their chemical signatures (cuticular hydrocarbons) compared to native populations of the same species. The reduced variability in these major recognition cues could be caused by a reduction of genetic diversity due to a genetic bottleneck. This hypothesis was tested in an inbred European population of the invasive hornet Vespa velutina nigrithorax.

Varroa destructor changes its cuticular hydrocarbons to mimic new hosts.

Varroa destructor (Vd) is a honeybee ectoparasite. Its original host is the Asian honeybee, Apis cerana, but it has also become a severe, global threat to the European honeybee, Apis mellifera. Previous studies have shown that Varroa can mimic a host's cuticular hydrocarbons (HC), enabling the parasite to escape the hygienic behaviour of the host honeybees.

Population diversity in cuticular hydrocarbons and mtDNA in a mountain social wasp.

Nestmate recognition is a common phenomenon in social insects that typically is mediated by cuticular hydrocarbons. Geographical variation in cuticular hydrocarbons has been observed, although the pattern of variation is not consistent across species and is usually related to the biology and ecology of the different species. Polistes biglumis (Hymenoptera: Vespidae) is a social wasp that lives in high mountains where populations are separated by significant geographical barriers.

Ant cuticular response to phthalate pollution.

Phthalates are common atmospheric contaminants used in the plastic industry. Ants have been shown to constitute good bioindicators of phthalate pollution. Hence, phthalates remain trapped on ant cuticles which are mostly coated with long-chain hydrocarbons.

Endocrine control of cuticular hydrocarbon profiles during worker-to-soldier differentiation in the termite Reticulitermes flavipes.

The social organization of termites, unlike that of other social insects, is characterized by a highly plastic caste system. With the exception of the alates, all other individuals in a colony remain at an immature stage of development. Workers in particular remain developmentally flexible; they can switch castes to become soldiers or neotenics.

Environmental and hormonal factors controlling reversible colour change in crab spiders.

Habitat heterogeneity that occurs within an individual's lifetime may favour the evolution of reversible plasticity. Colour reversibility has many different functions in animals, such as thermoregulation, crypsis through background matching and social interactions. However, the mechanisms underlying reversible colour changes are yet to be thoroughly investigated.

Seasonal selection and resource dynamics in a seasonally polyphenic butterfly.

Seasonal polyphenisms are widespread in nature, yet the selective pressures responsible for their evolution remain poorly understood. Previous work has largely focussed either on the developmental regulation of seasonal polyphenisms or putative 'top-down' selective pressures such as predation that may have acted to drive phenotypic divergence. Much less is known about the influence of seasonal variation in resource availability or seasonal selection on optimal resource allocation.

Ant cuticles: a trap for atmospheric phthalate contaminants.

Phthalates are universal contaminants. We show that they are trapped by the ant cuticles and maintained permanently at a low level, generally less than 1% of cuticular components. They are found throughout the interior of the insect, predominately in the fat body, which suggests that they are adsorbed by the cuticle.

Cleptoparasites, social parasites and a common host: chemical insignificance for visiting host nests, chemical mimicry for living in.

Social insect colonies contain attractive resources for many organisms. Cleptoparasites sneak into their nests and steal food resources. Social parasites sneak into their social organisations and exploit them for reproduction.

Responses of cricket cercal interneurons to realistic naturalistic stimuli in the field.

The ability of the insect cercal system to detect approaching predators has been studied extensively in the laboratory and in the field. Some previous studies have assessed the extent to which sensory noise affects the operational characteristics of the cercal system, but these studies have only been carried out in laboratory settings using white noise stimuli of unrealistic nature. Using a piston mimicking the natural airflow of an approaching predator, we recorded the neural activity through the abdominal connectives from the terminal abdominal ganglion of freely moving wood crickets (Nemobius sylvestris) in a semi-field situation.

Variations in worker cuticular hydrocarbons and soldier isoprenoid defensive secretions within and among introduced and native populations of the subterranean termite, Reticulitermes flavipes.

In social insects, cuticular hydrocarbons (CHCs) play a central role in nestmate recognition. CHCs have proved to be useful for identifying species and differentiating populations. In combination with CHCs, isoprenoid soldier defensive secretions (SDSs) have been previously used in some termite species for chemotaxonomic analyses.

Modifications of the chemical profile of hosts after parasitism allow parasitoid females to assess the time elapsed since the first attack.

In solitary parasitoids, only one adult can emerge from a given host. In some of these species, when several eggs are laid on the same host, supernumerary individuals are eliminated by lethal larval fights. In the solitary parasitoid Anisopteromalus calandrae, the probability of a second larva winning the fight depends on the time elapsed since the first oviposition.

Cryptic color change in a crab spider (Misumena vatia): identification and quantification of precursors and ommochrome pigments by HPLC.

Mimicry is used widely by arthropods to survive in a hostile environment. Often mimicry is associated with the production of chemical compounds such as pigments. In crab spiders, the change of color is based on a complex physiological process that still is not understood.

Hydrocarbons in the ant Lasius niger: from the cuticle to the nest and home range marking.

The cuticular hydrocarbons (CHCs) of the ant Lasius niger are described. We observe a high local colony specificity of the body cuticular profile as predicted for a monogynous and multicolonial species. The CHCs show a low geographical variation among different locations in France.

Identification of a widespread monomolecular odor differentially attractive to several Delia radicum ground-dwelling predators in the field.

Dimethyl disulfide (DMDS) was identified as a major volatile constituent of Brassica napus roots heavily infested by Delia radicum, the cabbage root fly. Attractiveness of this widespread compound was tested in the field in a naturally complex odorous environment. By using an original setup especially designed for ground dwelling beetles, different concentrations of the pure molecule as well as attractiveness of the natural blend emitted by the rotten part of infested roots were tested simultaneously.

Escape performance decreases during ontogeny in wild crickets.

Increasing the ecological relevance of studies relating to the performance of organisms has been a central issue for functional biologists over the last few years. Of particular concern are changes in performance throughout the life cycle as selective forces act differently on various life stages. We addressed this issue experimentally by following ontogenic variations in the escape performance of crickets threatened by artificial predatory signals.

Cuticular hydrocarbon composition reflects genetic relationship among colonies of the introduced termite Reticulitermes santonensis feytaud.

Nestmate recognition plays a key role in kin selection to maintain colony integrity in social insects. Previous studies have demonstrated that nestmate recognition is dependent on detection of cuticular hydrocarbons. However, the absence of intraspecific aggression between some colonies of Isoptera and social Hymenoptera questions whether kin recognition must occur in social insects.

Energy dynamics in a parasitoid foraging in the wild.

Although parasitoids are used widely as a biological models for understanding the evolution of animal behaviour, most studies have been constrained to the laboratory. The dearth of field studies has been compounded by the almost complete ignorance of the physiological parameters involved in foraging and dispersal, in particular of the energetic constraints imposed by resource limitation. We estimated the dynamics of carbohydrates and lipids reserves of Venturia canescens (Gravenhorst) females by releasing individuals of known nutritional status in a natural environment and recapturing them using host-containing traps.

High-performance ion-pair chromatography method for simultaneous analysis of alliin, deoxyalliin, allicin and dipeptide precursors in garlic products using multiple mass spectrometry and UV detection.

The quality of garlic and garlic products is usually related to their alliin content and allicin release potential. Until now no analytical method was able to quantify simultaneously allicin, its direct precursor alliin (S-allyl-L-cysteine sulfoxide), SAC (S-allyl-L-cysteine) as well as various dipeptides that apparently serve as storage compounds in garlic. It is well known that all these intermediates are involved in the allicin biosynthetic pathway.

Aroma analysis of fresh and preserved onions and leek by dual solid-phase microextraction-liquid extraction and gas chromatography-mass spectrometry.

The lachrymatory factor (thiopropanal-S-oxide) was directly analysed on fresh onion (Allium cepa) juice by solid-phase microextraction (polyacrylate fibre) using a fast routine GC-MS method on a 10 m x 0.32 mm I.D.

5,10-methylenetetrahydrofolate reductase common mutations, folate status and plasma homocysteine in healthy French adults of the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) cohort.

The 677cytosine mutation identified in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been frequently associated with an elevated plasma homocysteine concentration. The aim of the present study was to determine the impact of this MTHFR common mutation on plasma and erythrocyte folate (RCF) and plasma total homocysteine (tHcy) concentrations in healthy French adults. A cohort of 291 subjects living in the Paris area and participating in the Supplementation en Vitamines et Mineraux Antioxydants (SU.

Relationship between maternal folate status and foetal hypotrophy in a population with a good socio-economical level.

A longitudinal study was conducted on 2 groups of pregnant women according to the presence (n = 8) or absence (n = 13) of IUGR through echography at the 3rd trimester of pregnancy. Mothers answered a general questionnaire, including some alimentary data. Anthropometric measures from the newborns were recorded.

Effect of folic acid deficiency upon lymphocyte subsets from lymphoid organs in mice.

1. Three groups of weanling C57BL/6 female mice were fed one of two folate-deficient diets (0 and 0.1 mg folic acid/kg diet) or a normal folate-containing diet (2 mg folic acid/kg diet) for 8 weeks.

Blood levels of water-soluble vitamins in pediatric patients on total parenteral nutrition using a multiple vitamin preparation.

Although guidelines for the parenteral use of vitamin preparations in pediatric patients have been published, there are very limited data on the efficiency of these preparations and on the exact needs of infants and children on total parenteral nutrition (TPN). We report here an open, prospective, study of the blood levels of water-soluble vitamins in infants and children on TPN before and during supplementation with a new water-soluble multivitamin formula containing per vial unit: B1, 3 mg; B2, 3.6 mg; B6, 4 mg; niacin, 40 mg; pantothenate, 15 mg; ascorbate, 100 mg; biotin, 60 micrograms; folic acid, 400 micrograms; B12, 5 micrograms.

Oocyte size and intrafollicular position in polyovular follicles in rabbits.

Healthy follicles with 2-24 oocytes were observed in adult rabbit ovaries during all phases of folliculogenesis from primary to preovulatory follicles. Most follicles contained 2-3 oocytes which developed according to their topographical situation in the follicle. The central oocyte in a normal topographical situation has an almost normal growth and development up to metaphase II and cumulus expansion.