Effects of temperature on a Chinese population of Amblyseius andersoni (Acari: Phytoseiidae) fed with Tetranychus urticae

International audienceThe development and fecundity of Amblyseius andersoni (Chant) fed with Tetranychus urticae Koch was studied at five different temperatures (17, 20, 25, 30 and 35 °C) and life parameters of the population were calculated. The development, reproduction, longevity, and life table parameters of A. andersoni were significantly affected by the different temperatures. The duration of the egg, larval, protonymph, deutonymph and total immature stages were reduced when the temperature increased. The total oviposition of A. andersoni was highest at 25 °C and lowest at 35 °C, and the daily average oviposition increased as the temperature increased, but few eggs were laid at 17 °C. The values of the intrinsic rate of increase (rm, 0.108--0.200), net reproduction rate (R0, 18.71--36.47) and the mean generation time (T, 14.68--29.73) significantly differed among the five temperatures. The highest net reproduction rate (R0 = 36.47) was obtained at 25 °C. The results of this study indicated that A. andersoni has a high inherent potential for the control of the T. urticae at certain temperatures

The Third Order Scalar Induced Gravitational Waves

Since the gravitational waves were detected by LIGO and Virgo, it has been promising that lots of information about the primordial Universe could be learned by further observations on stochastic gravitational waves background. The studies on gravitational waves induced by primordial curvature perturbations are of great interest. The aim of this paper is to investigate the third order induced gravitational waves. Based on the theory of cosmological perturbations, the first order scalar induces the second order scalar, vector and tensor perturbations. At the next iteration, the first order scalar, the second order scalar, vector and tensor perturbations all induce the third order tensor perturbations. We present the energy density spectrum of the third order gravitational waves for a monochromatic primordial power spectrum. The shape of the energy density spectrum of the third order gravitational waves is different from that of the second order scalar induced gravitational waves. And it is found that the third order gravitational waves sourced by the second order scalar perturbations dominate the energy density spectrum.Comment: 33 pages, 4 figure

Primordial black holes from second order density perturbations as probes of the small-scale primordial power spectrum

We investigate the second order energy density perturbation $\delta^{(2)}$ induced by small-scale Gaussian and local-type non-Gaussian primordial curvature perturbations. The relative abundance of primordial black hole is calculated in terms of the probability density function of total energy density perturbation $\delta_r=\delta^{(1)}+\frac{1}{2}\delta^{(2)}$. The effects of second order density perturbation greatly reduce the upper bounds of small-scale power spectra of primordial curvature perturbations by one to two orders of magnitude. For log-normal primordial power spectrum, its amplitude $A_{\zeta}$ is constrained to be about $A_{\zeta}\sim 3\times10^{-3}$. And for local-type non-Gaussianity with $f_{\mathrm{NL}}=10$, the upper bound of $A_{\zeta}$ is about $2.5\times10^{-4}$.Comment: 5 pages, 4 figure

A First Study of the Virulence Potential of a Bacillus subtilis Isolate From Deep-Sea Hydrothermal Vent

Bacillus subtilis is the best studied Gram-positive bacterium, primarily as a model of cell differentiation and industrial exploitation. To date, little is known about the virulence of B. subtilis. In this study, we examined the virulence potential of a B. subtilis strain (G7) isolated from the Iheya North hydrothermal field of Okinawa Trough. G7 is aerobic, motile, endospore-forming, and requires NaCl for growth. The genome of G7 is composed of one circular chromosome of 4,216,133 base pairs with an average GC content of 43.72%. G7 contains 4,416 coding genes, 27.5% of which could not be annotated, and the remaining 72.5% were annotated with known or predicted functions in 25 different COG categories. Ten sets of 23S, 5S, and 16S ribosomal RNA operons, 86 tRNA and 14 sRNA genes, 50 tandem repeats, 41 mini-satellites, one microsatellite, and 42 transposons were identified in G7. Comparing to the genome of the B. subtilis wild type strain NCIB 3610T, G7 genome contains many genomic translocations, inversions, and insertions, and twice the amount of genomic Islands (GIs), with 42.5% of GI genes encoding hypothetical proteins. G7 possesses abundant putative virulence genes associated with adhesion, invasion, dissemination, anti-phagocytosis, and intracellular survival. Experimental studies showed that G7 was able to cause mortality in fish and mice following intramuscular/intraperitoneal injection, resist the killing effect of serum complement, and replicate in mouse macrophages and fish peripheral blood leukocytes. Taken together, our study indicates that G7 is a B. subtilis isolate with unique genetic features and can be lethal to vertebrate animals once being introduced into the animals by artificial means. These results provide the first insight into the potential harmfulness of deep-sea B. subtilis

Use of Indigenous Hanseniaspora vineae and Metschnikowia pulcherrima Co-fermentation With Saccharomyces cerevisiae to Improve the Aroma Diversity of Vidal Blanc Icewine

Using novel non-Saccharomyces strains is regarded as an effective way to improve the aroma diversity of wines to meet the expectations of consumers. The non-Saccharomyces Hanseniaspora vineae and Metschnikowia pulcherrima have good aromatic properties useful for the production of table wine. However, no detailed information is available on their performances in icewine fermentation. In this study, simultaneous and sequential fermentation trials of indigenous M. pulcherrima CVE-MP20 or H. vineae CVE-HV11 with S. cerevisiae (SC45) were performed in 50-L fermenters of Vidal icewine, respectively. The results showed that SC45 cofermented with different non-Saccharomyces strains could generate a distinct aroma quality of icewine compared with four S. cerevisiae strain monocultures as evidenced by principal component analysis (PCA). Mixed fermentation of MP20/SC45 produced higher contents of acetate esters and β-damascenone with lower C6 alcohols relative to SC45 monoculture. Interestingly, HV11/SC45 generated the highest amounts of C6 alcohols [(Z)-3-hexen-1-ol and (E)-3-hexen-1-ol], higher alcohols (isobutanol, isopentanol, and 2-phenylethanol), acetate esters (2-phenethyl acetate and isoamyl acetate), cis-rose oxide, β-damascenone, and phenylacetaldehyde. Compared with simultaneous inoculation, sequential inoculation could achieve higher aroma diversity and produce higher intensity of fruity, flowery, and sweet attributes of icewine as assessed by calculating the odor activity values (OAVs). Our results verified the desired enological characteristics of H. vineae strain in icewine fermentation and also demonstrated that using indigenous non-Saccharomyces and Saccharomyces strains is a feasible way to improve aroma diversity of icewine products, which could provide an alternative way to meet the requirement of wine consumers for diversified aromatic quality

Two-dimensional flow visualization and velocity measurement in natural convection near indoor heated surfaces using a thermal image velocimetry method

Indoor velocity measurement techniques are categorized into point-wise and global-wise measurement techniques. Currently, measurements are either intrusive or restricted to the measurement area. This study presents a thermal image velocimetry (TIV)-based flow measurement method that is suitable for visualizing indoor two-dimensional velocity fields near indoor heated surfaces. The proposed technique uses only an infrared camera for mapping the surface temperature fluctuations. Image processing steps that are used to recover the velocity distribution include the decomposition of the video files into individual frames, the application of filtering to remove background noise, cross-calculation to estimate the velocity, and a final velocity correction based on the continuity equation. To investigate the feasibility of this method, natural convection was studied close to a heated vertical surface in a rectangular cavity. Thermal image velocimetry and particle image velocimetry (PIV) were used to visualize the flow field above a heating unit. The results indicate that the airflow field can be visualized by TIV, and the results measured by TIV are shown to be similar to those for the surface of 6 mm away from the heated surface measured by PIV. A linear correlation is established between TIV and PIV