Can \u3cem\u3eDarapsa myron\u3c/em\u3e (Lepidoptera: Sphingidae) Successfully Use the Invasive Plant \u3cem\u3eAmpelopsis brevipedunculata\u3c/em\u3e as a Food Resource?

Although biological invasions are generally thought to negatively impact native fauna, native herbivores that can utilize invasive plants may benefit. The East Coast of the United States has been invaded by the vitaceous plant Ampelopsis brevipedunculata. The invaded range of A. brevipedunculata overlaps with that of the native Vitis labrusca, a closely-related species that is a host plant for the native moth Darapsa myron (Lepidoptera: Sphingidae). We reared D. myron larvae on either V. labrusca or A. brevipedunculata to assess whether development and survival differed on the two plant species. Larval growth and survival to pupation was only 5% on A. brevipedunculata compared to 30% on V. labrusca, suggesting that the invasive species is an unsuitable hostplant for D. myron

A Time-Orbiting Potential Trap for Bose-Einstein Condensate Interferometry

We describe a novel atom trap for Bose-Einstein condensates of 87Rb to be used in atom interferometry experiments. The trap is based on a time-orbiting potential waveguide. It supports the atoms against gravity while providing weak confinement to minimize interaction effects. We observe harmonic oscillation frequencies omega_x, omega_y, omega_z as low as 2 pi times (6.0,1.2,3.3) Hz. Up to 2 times 10^4 condensate atoms have been loaded into the trap, at estimated temperatures as low as 850 pK. We anticipate that interferometer measurement times of 1 s or more should be achievable in this device.Comment: 9 pages, 3 figure

Datana drexelii (Lepidoptera: Notododontidae) occurrence and larval survival on highbush blueberry cultivars

Plant genotype influences plant suitability to herbivores; domesticated plants selected for properties such as high fruit yield may be particularly vulnerable to herbivory. Cultivated strains of highbush blueberry, Vaccinium corymbosum L. can be high-quality hosts for larvae of the gregariously-feeding notodontid Datana drexelii (Hy. Edwards). We conducted an experiment assessing D. drexelii larval survival and pupal weight when fed foliage from five blueberry cultivars: ‘Bluecrop’, ‘Bluetta’, ‘Blueray’, ‘Lateblue’, and ‘Jersey’. We complemented this experimental work with repeated bush-level surveys of a managed blueberry patch for naturally occurring D. drexelii larval clusters. Larval survival and pupal weight were significantly higher on ‘Lateblue’ foliage than from the ‘Bluecrop’, ‘Bluetta’, and ‘Jersey’ cultivars. The blueberry patch surveys found more D. drexelii larval clusters on ‘Bluehaven’, ‘Collins’, and ‘Darrow’ bushes than on the cultivars ‘Earliblue’ and ‘Jersey’. The low D. drexelii occurrence and performance on the ‘Jersey’ cultivar suggests that this variety may be appropriate for areas where this pest is common; conversely, their high occurrence on ‘Bluehaven’ ‘Collins’, and ‘Darrow’ suggests that these cultivars may be particularly vulnerable. Cultivar-level variation in herbivore vulnerability highlights how understanding plant-pest interactions can help manage agricultural species

Probing the inter-layer exciton physics in a MoS2_2/MoSe2_2/MoS2_2 van der Waals heterostructure

Stacking atomic monolayers of semiconducting transition metal dichalcogenides (TMDs) has emerged as an effective way to engineer their properties. In principle, the staggered band alignment of TMD heterostructures should result in the formation of inter-layer excitons with long lifetimes and robust valley polarization. However, these features have been observed simultaneously only in MoSe$_2$/WSe$_2$ heterostructures. Here we report on the observation of long lived inter-layer exciton emission in a MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructure. The inter-layer nature of the observed transition is confirmed by photoluminescence spectroscopy, as well as by analyzing the temporal, excitation power and temperature dependence of the inter-layer emission peak. The observed complex photoluminescence dynamics suggests the presence of quasi-degenerate momentum-direct and momentum-indirect bandgaps. We show that circularly polarized optical pumping results in long lived valley polarization of inter-layer exciton. Intriguingly, the inter-layer exciton photoluminescence has helicity opposite to the excitation. Our results show that through a careful choice of the TMDs forming the van der Waals heterostructure it is possible to control the circular polarization of the inter-layer exciton emission.Comment: 19 pages, 3 figures. Just accepted for publication in Nano Letters (http://pubs.acs.org/doi/10.1021/acs.nanolett.7b03184

Predator Cues Increase Silkmoth Mortality

While prey responses to predators reduce the threat of consumption, the physiological costs of these responses can be considerable. This is especially true for organisms that lack effective anti-predator defenses and must rely on camouflage or mimicry for protection. The luna moth, Actias luna, is a large saturniid native to Eastern North America that is preyed on and parasitized by a wide variety of predators and parasitoids. We report the results of two separate experiments assessing the responses of Actias larvae to predatory wasps (Vespula maculifrons) that were rendered non-lethal but remained able to move freely, as well as in a control (wasp-free) treatment. We determined whether these responses were predator-specific by also testing the response of Actias larvae to a similarly-sized but harmless scavenging fly. In both experiments, (A) Actias larvae in the wasp treatment died at a higher rate than those in the control treatments; and (B) larval survival in the fly and control treatments did not differ. Despite similar Actias survival in the fly and control treatments, fly-treatment larvae that died appeared to respond similarly to flies as other larvae did to wasps. In both years, larvae that died in the fly and wasp treatments gained virtually no weight between the start of the experiment and their death, suggesting that they may have succumbed to starvation. Our results, replicated over 2 years, illustrate the high cost of anti-predator responses and are the first report of lethal risk effects in caterpillars

Non equilibrium anisotropic excitons in atomically thin ReS2_2

We present a systematic investigation of the electronic properties of bulk and few layer ReS$_2$ van der Waals crystals using low temperature optical spectroscopy. Weak photoluminescence emission is observed from two non-degenerate band edge excitonic transitions separated by $\sim$ 20 meV. The comparable emission intensity of both excitonic transitions is incompatible with a fully thermalized (Boltzmann) distribution of excitons, indicating the hot nature of the emission. While DFT calculations predict bilayer ReS$_2$ to have a direct fundamental band gap, our optical data suggests that the fundamental gap is indirect in all cases

Versatile transporter apparatus for experiments with optically trapped Bose-Einstein condensates

We describe a versatile and simple scheme for producing magnetically and optically-trapped Rb-87 Bose-Einstein condensates, based on a moving-coil transporter apparatus. The apparatus features a TOP trap that incorporates the movable quadrupole coils used for magneto-optical trapping and long-distance magnetic transport of atomic clouds. As a stand-alone device, this trap allows for the stable production of condensates containing up to one million atoms. In combination with an optical dipole trap, the TOP trap acts as a funnel for efficient loading, after which the quadrupole coils can be retracted, thereby maximizing optical access. The robustness of this scheme is illustrated by realizing the superfluid-to-Mott insulator transition in a three-dimensional optical lattice

Facilitation between invasive herbivores: hemlock woolly adelgid increases gypsy moth preference for and performance on eastern hemlock

Interactions between invertebrate herbivores with different feeding modes are common on long‐lived woody plants. In cases where one herbivore facilitates the success of another, the consequences for their shared host plant may be severe. Eastern hemlock (Tsuga canadensis), a canopy‐dominant conifer native to the eastern U.S., is currently threatened with extirpation by the invasive stylet‐feeding hemlock woolly adelgid (Adelges tsugae). The effect of adelgid on invasive hemlock‐feeding folivores remains unknown. This study evaluated the impact of feeding by hemlock woolly adelgid on gypsy moth (Lymantria dispar) larval preference for, and performance on, eastern hemlock. To assess preference, 245 field‐grown hemlocks were surveyed for gypsy moth herbivory damage and laboratory paired‐choice bioassays were conducted. To assess performance, gypsy moth larvae were reared to pupation on adelgid‐infested or uninfested hemlock foliage, and pupal weight, proportional weight gain, and larval period were analysed. Adelgid‐infested hemlocks experienced more gypsy moth herbivory than did uninfested control trees, and laboratory tests confirmed that gypsy moth larvae preferentially feed on adelgid‐infested hemlock foliage. Gypsy moth larvae reared to pupation on adelgid‐infested foliage gained more weight than larvae reared on uninfested control foliage. These results suggest that the synergistic effect of adelgid and gypsy moth poses an additional threat to eastern hemlock that may increase extirpation risk and ecological impact throughout most of its range