Pre-imaginal exposure to Oberon® disrupts fatty acid composition, cuticular hydrocarbon profile and sexual behavior in Drosophila melanogaster adults.

Oberon® is a commercial formulation of spiromesifen, a pesticide inhibitor of lipid biosynthesis via acetyl CoA carboxylase, widely used in agricultural crop protection. However, its mode of action requires further analysis. We currently examined the effect of this product on Drosophila melanogaster as a non-target and model organism. Different concentrations of spiromesifen were administered by ingestion (and contact) during pre-imaginal development, and we evaluated its delayed action on adults. Our results suggest that spiromesifen induced insecticidal activity on D. melanogaster. Moreover, spiromesifen treatment significantly increased the duration of larval and pupal development at all tested concentrations while it shortened longevity in exposed males as compared to control males. Also, pre-imaginal exposure to spiromesifen quantitatively affected fatty acids supporting its primary mode of action on lipid synthesis. In addition, this product was found to modify cuticular hydrocarbon profiles in exposed female and male flies as well as their sexual behavior and reproductive capacity.

Measurement of the Spectral Shape of the ß-Decay of

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique ß-decay transition ^{137}Xe(7/2^{-})→^{137}Cs(7/2^{+}). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique ß-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

Search for Neutrinoless Double-ß Decay with the Complete EXO-200 Dataset.

A search for neutrinoless double-ß decay (0νßß) in ^{136}Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0νßß and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4±3.0%, and the energy resolution of the detector at the Q value of ^{136}Xe 0νßß has been improved from σ/E=1.23% to 1.15±0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0νßß half-life sensitivity for this analysis is 5.0×10^{25} yr with a total ^{136}Xe exposure of 234.1 kg yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 3.5×10^{25} yr at the 90% confidence level.

Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector.

Results from a search for neutrinoless double-beta decay (0νßß) of ^{136}Xe are presented using the first year of data taken with the upgraded EXO-200 detector. Relative to previous searches by EXO-200, the energy resolution of the detector has been improved to σ/E=1.23%, the electric field in the drift region has been raised by 50%, and a system to suppress radon in the volume between the cryostat and lead shielding has been implemented. In addition, analysis techniques that improve topological discrimination between 0νßß and background events have been developed. Incorporating these hardware and analysis improvements, the median 90% confidence level 0νßß half-life sensitivity after combining with the full data set acquired before the upgrade has increased twofold to 3.7×10^{25} yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 1.8×10^{25} yr at the 90% confidence level.

Dark Matter Search Results from the PICO-60 C_{3}F_{8} Bubble Chamber.

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C_{3}F_{8} located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C_{3}F_{8} exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41} cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.

Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber.

New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5×10(-10) and an alpha rejection factor of >98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe.

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.

Search for neutrinoless double-beta decay in 136Xe with EXO-200.

We report on a search for neutrinoless double-beta decay of 136Xe with EXO-200. No signal is observed for an exposure of 32.5 kg yr, with a background of ∼1.5×10(-3) kg(-1) yr(-1) keV(-1) in the ±1σ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay T(1/2)(0νßß)(136Xe)>1.6×10(25) yr (90% C.L.), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation.

Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector.

We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

A magnetically driven piston pump for ultra-clean applications.

A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon time projection chamber of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute of xenon gas with 750 Torr differential pressure.

A simple radionuclide-driven single-ion source.

We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating (148)Gd onto a silicon α-particle detector and vapor depositing a layer of BaF(2) over it. (144)Sm recoils from the alpha decay of (148)Gd are used to dislodge Ba(+) ions from the BaF(2) layer and emit them in the surrounding environment. The simultaneous detection of an α particle in the substrate detector allows for tagging of the nuclear decay and of the Ba(+) emission. The source is simple, durable, and can be manipulated and used in different environments. We discuss the fabrication process, which can be easily adapted to emit most other chemical species, and the performance of the source.

Effects of tebufenozide on ovarian growth and sexual behavior in the German cockroach (Blattella germanica).

Tebufenozide, a dibenzoylhydrazine insect growth regulator, was applied topically (1 microg/insect) on female adults of the German cockroach Blattella germanica and its effects on ovarian measurement and proteins contents were investigated during the first gonadotrophic cycle (0, 2, 4 and 6 days). Dissection of treated females showed a clear reduction in oocyte numbers and volume of the basal oocyte. The ovarian proteins content was also significantly reduced. Behavioral tests demonstrated that treatment of 6-days-old females with tebufenozide caused in 80% of the males an increase in numbers of antennal contacts, but there was no effect on the numbers of wing raisings. In contrast, it was striking that in 20% of the males there was a total loss of antennal contacts and wings raisings in response to a calling treated female. These behavior effects are probably caused by a reduced production of contact sex pheromone in the females and may help in explaining the lower ovary reproductive parameters.

Independent measurement of the total active 8B solar neutrino flux using an array of 3He proportional counters at the Sudbury Neutrino Observatory.

The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) 8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

The Cryptocercus punctulatus species complex (Dictyoptera: Cryptocercidae) in the eastern United States: comparison of cuticular hydrocarbons, chromosome number, and DNA sequences.

The goal of the current study was to determine if cuticular hydrocarbons could be used to empirically delimit taxa within the Cryptocercus punctulatus species complex in the eastern United States. Cockroaches were collected from rotting logs in 22 locations across four states. Hydrocarbon phenotypes and two mitochondrial (16S and COII) genes and one nuclear (ITS2) gene were independently analyzed to determine their relationship with chromosome number. Five distinct hydrocarbon phenotypes were found, but these were only partly congruent with chromosome number and thus with purported species descriptions. Molecular and cuticular hydrocarbon data each indicate that Cryptocercus with a male karyotype of 2n=43 belong to at least two distinct, distantly related lineages. One 2n=43 lineage is sister group to the 2n=37 and 2n=39 clade, and has a unique hydrocarbon profile. The other 2n=43 lineage is sister group to the 2n=45 samples, and its cuticular hydrocarbons group with four samples of the 2n=45 lineage. The cuticular hydrocarbons of two additional 2n=45 samples diverge from this assemblage. Results indicate cuticular hydrocarbons and chromosome number have some degree of evolutionary independence; neither is completely reliable in delineating historical lineages. Our data provide support for the parallel model of chromosome evolution in the species complex.

Cuticular hydrocarbon profiles in Blattella germanica: effects of halofenozide, boric acid and benfuracarb.

In order to complete previous studies conducted on Blattella germanica, three insecticides from different groups were evaluated: boric acid, an inorganic compound, benfuracarb, a carbamate, and halofenozide, a non-steroidal ecdysone agonist. Boric acid (8.20%, LD50) and benfuracarb (2%, LD50) were incorporated into the diet and orally administrated to newly emerged adults of both sexes, while halofenozide (0.33%, LD50) was applied topically. Hydrocarbons extracts was made on bidistilled pentane from control and treated series sampled 6 days following treatment. Extracts was analyzed by gas chromatography. Data showed that cuticular profiles of control and treated series were qualitatively similar with thirteen major compounds; however, significant quantitative differences were noted. Boric acid seemed to feminize the cuticular profile in males with a significant reduction of the two first cuticular compounds detected. Halofenozide and benfuracarb reduced cuticular compounds in both sexes.

Measurement of the total active 8B solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity.

The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27(stat)+/-0.38(syst) x 10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(+1.2)(-0.6) x 10(-5) eV(2) and theta=32.5(+2.4)(-2.3) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

Constraints on nucleon decay via invisible modes from the Sudbury Neutrino Observatory.

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes.

Reproductive effects in German cockroaches by ecdysteroid agonist RH-0345, juvenile hormone analogue methoprene and carbamate benfuracarb.

Blatta germanica is the more prevalent cockroach species in Algeria. In the present study, we tested the effect on reproduction in B. germanica of two insect growth regulators, RH-0345, a benzoylhydrazine analogue that mimics the action of 20-hydroxyecdysone, and methoprene, one of the most commercially important juvenile hormone analogues, and a novel carbamate insecticide, benfuracarb. The compounds were applied topically (10 and 20 microg/insect for RH-0345, and 1 and 10 microg/insect for methoprene) or orally administrated (at 2% for benfuracarb) on newly emerged females and evaluated on reproductive events during the adult life (2, 4 and 6 days). Treatment with RH-0345 and benfuracarb reduced significantly the number of oocytes, the size and the volume of the basal oocyte during the experimental period. Methoprene distorted the ovarian development since it caused a significant reduction in the number of oocytes at 2, 4 and 6 days for the two tested doses, and an increase in oocyte size at 2, 4 and 6 days with 1 microg and a decrease with 10 microg. In a second series of experiments, the effects of these compounds were assayed on the ovarian proteins. Data from biochemical analysis revealed that RH-0345 and benfuracarb reduced the ovarian amounts of proteins, while treatment with methoprene increased it during the sexual maturation.

Molecular characterization of Lma-p54, a new epicuticular surface protein in the cockroach Leucophaea maderae (Dictyoptera, oxyhaloinae).

The epicuticular surface protein Lma-p54 is imbedded in the "cuticular waxes" which cover the abdominal surface of the adult Leucophaea maderae. Natural Lma-p54 was purified and the complete cDNA sequence was determined by RT-PCR using primers based on Edman degradation fragments. Northern blot and in situ hybridization analyses showed that Lma-p54 was expressed in the adult abdominal epidermis and in the chemical sense organs of both sexes. Sequence alignment indicates that Lma-p54 is closely related to aspartic proteases (EC 3.4.23). However, there are critical amino acid substitutions at the level of the active site and, since no proteolytic activity was detected in the abdominal secretion, the protein is likely inactive. As an inactive aspartic protease, Lma-p54 is related to pregnancy-associated glycoproteins (PAGs) which still present a peptide-binding ability. According to recent experiments using whole tergal protein secretions, a role in intraspecific contact recognition was proposed for this surface protein.

Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory.

Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.