Search results for "SEX"
showing 10 items of 4056 documents
Biology and Behaviour of Cirrospilus diallus and Cirrospilus pictus, Parasitoids of Phyllocnistis citrella
2005
International audience; Studies were carried out on some biological and behavioral aspects of Cirrospilus diallus Walker and Cirrospilus pictus (Nees) (Hymenoptera: Eulophidae) in relation to their host, the citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Adults of both species fed with sugar lived on average 4.45 +/- 0.19 days, whereas adults provided with honey survived on average 40.62 +/- 1.97 days. Rates of host mortality due to parasitoid stings without oviposition were as high as 31.25 and 37.73% for C. pictus and C. diallus, respectively. Both species showed arrhenotokous parthenogenesis. Sex ratios of parasitoids emerging from the 2nd and 3rd …
Sex versus parthenogenesis: A transcriptomic approach of photoperiod response in the model aphid Acyrthosiphon pisum (Hemiptera: Aphididae)
2007
International audience; Most aphids develop a cyclic parthenogenesis life-cycle. After several generations of viviparous parthenogenetic females, it follows a single annual generation of sexual individuals, usually in autumn, that mate and lay the sexual eggs. Shortening of photoperiod at the end of the summer is a key factor inducing the sexual response. With the survey here reported we aimed at identifying a collection of candidate genes to participate at some point in the cascade of events that lead to the sexual phenotypes. Following a suppression subtractive hybridization methodology (SSH) on the model aphid Acyrthosiphon pisum, we built and characterised two reciprocal cDNA libraries …
Sex pheromone identified after solid phase microextraction from tergal glands of female alates in Cornitermes bequaerti (Isoptera, Nasutitermitinae)
2002
For the first time, a termite sex pheromone secreted by tergal glands has been isolated and identified. In the mandibulate nasute termite Cornitermes bequaerti, pairing of swarming imagoes is mediated by a sex pheromone secreted by females from their tergal glands. These well developed sexual glands located in front of tergites 8, 9, 10 are essentially composed of class 1 and 2 cells, but also of some glandular units of class 3 cells. The major volatile compound of tergal secretion was isolated by solid phase microextraction (SPME) and identified by GC-MS as (3Z, 6Z, 8E)-dodecatrien-1-ol. Sex attraction bioassays with synthetic (3Z, 6Z, 8E)-dodecatrien-1-ol showed that this alcohol was the …
Degradation of sexual reproduction in Veronica filiformis after introduction to Europe
2011
Abstract Background Baker’s law predicts that self-incompatible plant species are generally poor colonizers because their mating system requires a high diversity of genetically differentiated individuals and thus self-compatibility should develop after long-distance dispersal. However, cases like the introduction of the self-incompatible Veronica filiformis (Plantaginaceae) to Europe constitute an often overlooked alternative to this rule. This species was introduced from subalpine areas of the Pontic-Caucasian Mountains and colonized many parts of Central and Western Europe in the last century, apparently without producing seeds. To investigate the consequences of the absence of sexual rep…
Growth patterns, sexual dimorphism, and maturation modeled in Pachypleurosauria from Middle Triassic of central Europe (Diapsida: Sauropterygia)
2018
Bone tissue, microanatomy, and growth are studied in humeri of the pachypleurosaurs Dactylosaurus from the early Anisian of Poland and of aff. Neusticosaurus pusillus from the Lettenkeuper (early Ladinian) of southern Germany. Histology and modeled growth curves are compared to already published data of other pachypleurosaurs. Therefore, we herein established growth curves for Anarosaurus from the middle Anisian of Winterswijk (the Netherlands) and for pachypleurosaurs from the Anisian/Ladinian of the Alpine Triassic (i.e., Neusticosaurus spp. and Serpianosaurus). Humeri of Dactylosaurus, Anarosaurus, and aff. N. pusillus, all from the Germanic Basin, usually display an inner ring of (pre-)…
Halophila stipulacea descriptors in the native area (Red Sea): A baseline for future comparisons with native and non-native populations
2018
Abstract Halophila stipulacea is a small tropical seagrass species native to the Red Sea. Due to its invasive character, there is growing interest in understanding its ability to thrive in a broad range of ecological niches. We studied temporal (February 2014 and July 2014), depth (5, 9, 18 m) and spatial (NB and SB) related dynamics of H. stipulacea meadows in the northern Gulf of Aqaba. We evaluated changes in density, morphometry, biomass, and biochemical parameters alongside the reproductive effort. In both sites, maximal growth and vegetative performance occurred in the summer with a marked increase of 35% in shoot density and 18% in biomass; PAR reduction with season and depth induced…
Constitutive Activation of the Midgut Response to Bacillus thuringiensis in Bt-Resistant Spodoptera exigua
2010
Bacillus thuringiensis is the most effective microbial control agent for controlling numerous species from different insect orders. The main threat for the long term use of B. thuringiensis in pest control is the ability of insects to develop resistance. Thus, the identification of insect genes involved in conferring resistance is of paramount importance. A colony of Spodoptera exigua (Lepidoptera: Noctuidae) was selected for 15 years in the laboratory for resistance to Xentari (TM), a B. thuringiensis-based insecticide, reaching a final resistance level of greater than 1,000-fold. Around 600 midgut ESTs were analyzed by DNA-macroarray in order to find differences in midgut gene expression …
Male sex pheromone of cockroach Eurycotis floridana (Walker) (Blattidae, Polyzosteriinae): role and composition of tergites 2 and 8 secretions
1994
0098-0331; In Eurycotis floridana, the male calling behavior is associated with the exposition of epidermal glands located under tergites 2, 7, and 8. 4-Hydroxy-5-methyl-3(2H)-furanone and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were recently identified as the specific components of tergite 7 secretion. Methylene chloride extracts of tergite 7 and its major compound 4-hydroxy-5-methyl-3(2H)-furanone attract the conspecific females at a distance. Methylene chloride extracts of tergite 8 are also attractive at a distance to the females, whereas extracts of tergite 2 had no effect on males and females. Our GC investigations showed the absence of specific compounds in tergite 2 secretions. The GC…
Stable isotopes reveal differences in diet among reed bunting subspecies that vary in bill size
2017
Reed bunting Emberiza schoeniclus subspecies vary considerably in bill size and shape and seem to be at an early stage of speciation, in which bill might be indirectly causing reproductive isolation. Hence, we evaluated whether bill size, as well as age and sex, are associated with foraging niche in three west European subspecies of reed bunting: the thin-billed schoeniclus, the intermediate-billed lusitanica and the thick-billed witherbyi. Blood sampling was undertaken at three sites in southwest Europe during the winter (when these subspecies co-occur), and stable isotope analyses (carbon and nitrogen) were performed to assess their foraging niches. Stable isotope analyses of potential fo…