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Evaluation of semiochemical based push-pull strategy for population suppression of ambrosia beetle vectors of laurel wilt disease in avocado.
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) bore into tree xylem to complete their life cycle, feeding on symbiotic fungi. Ambrosia beetles are a threat to avocado where they have been found to vector a symbiotic fungus, Raffaelea lauricola, the causal agent of the laurel wilt disease. We assessed the repellency of methyl salicylate and verbenone to two putative laurel wilt vectors in avocado, Xyleborus volvulus (Fabricius) and Xyleborus bispinatus (Eichhoff), under laboratory conditions. Then, we tested the same two chemicals released from SPLAT flowable matrix with and without low-dose ethanol dispensers for manipulation of ambrosia beetle populations occurring in commercial avocado. The potential active space of repellents was assessed by quantifying beetle catch on traps placed 'close' (~5-10 cm) and 'far' (~1-1.5 m) away from repellent dispensers. Ambrosia beetles collected on traps associated with all in-field treatments were identified to species to assess beetle diversity and community variation. Xyleborus volvulus was not repelled by methyl salicylate (MeSA) or verbenone in laboratory assays, while X. bispinatus was repelled by MeSA but not verbenone. Ambrosia beetle trap catches were reduced in the field more when plots were treated with verbenone dispensers (SPLAT) co-deployed with low-dose ethanol dispensers than when treated with verbenone alone. Beetle diversity was highest on traps deployed with low-dose ethanol lures. The repellent treatments and ethanol lures significantly altered the species composition of beetles captured in experiment plots. Our results indicate that verbenone co-deployed with ethanol lures holds potential for manipulating ambrosia beetle vectors via push-pull management in avocado. This tactic could discourage immigration and/or population establishment of ambrosia beetles in commercial avocado and function as an additional tool for management programs of laurel wilt
Phonon self-energy corrections to non-zero wavevector phonon modes in single-layer graphene
Phonon self-energy corrections have mostly been studied theoretically and
experimentally for phonon modes with zone-center (q = 0) wave-vectors. Here,
gate-modulated Raman scattering is used to study phonons of a single layer of
graphene (1LG) in the frequency range from 2350 to 2750 cm-1, which shows the
G* and the G'-band features originating from a double-resonant Raman process
with q \not= 0. The observed phonon renormalization effects are different from
what is observed for the zone-center q = 0 case. To explain our experimental
findings, we explored the phonon self-energy for the phonons with non-zero
wave-vectors (q \not= 0) in 1LG in which the frequencies and decay widths are
expected to behave oppositely to the behavior observed in the corresponding
zone-center q = 0 processes. Within this framework, we resolve the
identification of the phonon modes contributing to the G* Raman feature at 2450
cm-1 to include the iTO+LA combination modes with q \not= 0 and the 2iTO
overtone modes with q = 0, showing both to be associated with wave-vectors near
the high symmetry point K in the Brillouin zone
Observation of the Kohn anomaly near the K point of bilayer graphene
The dispersion of electrons and phonons near the K point of bilayer graphene
was investigated in a resonant Raman study using different laser excitation
energies in the near infrared and visible range. The electronic structure was
analyzed within the tight-binding approximation, and the
Slonczewski-Weiss-McClure (SWM) parameters were obtained from the analysis of
the dispersive behavior of the Raman features. A softening of the phonon
branches was observed near the K point, and results evidence the Kohn anomaly
and the importance of considering electron-phonon and electron-electron
interactions to correctly describe the phonon dispersion in graphene systems.Comment: 4 pages, 4 figure
The Structure of n-Point One-Loop Open Superstring Amplitudes
In this article we present the worldsheet integrand for one-loop amplitudes
in maximally supersymmetric superstring theory involving any number n of
massless open string states. The polarization dependence is organized into the
same BRST invariant kinematic combinations which also govern the leading string
correction to tree level amplitudes. The dimensions of the bases for both the
kinematics and the associated worldsheet integrals is found to be the unsigned
Stirling number S_3^{n-1} of first kind. We explain why the same combinatorial
structures govern on the one hand finite one-loop amplitudes of equal helicity
states in pure Yang Mills theory and on the other hand the color tensors at
quadratic alpha prime order of the color dressed tree amplitude.Comment: 75 pp, 8 figs, harvmac TeX, v2: published versio
Group theory analysis of electrons and phonons in N-layer graphene systems
In this work we study the symmetry properties of electrons and phonons in
graphene systems as function of the number of layers. We derive the selection
rules for the electron-radiation and for the electron-phonon interactions at
all points in the Brillouin zone. By considering these selection rules, we
address the double resonance Raman scattering process. The monolayer and
bilayer graphene in the presence of an applied electric field are also
discussed.Comment: 8 pages, 6 figure
Integrated control of two tortricid (Lepidoptera) pests in apple orchards with sex pheromones and insecticides.
The apple is attacked by a significant number of insect pests in Brazilian commercial orchards, including Bonagota salubricola and Grapholita molesta (Lepidoptera: Tortricidae). Sexual disruption of B. salubricola and G. molesta was evaluated in apple orchard using the flowable pheromone formulations, SPLAT Grafo+Bona (SG+B), SPLAT Attract and Kill Grafo+Bona (SAKG+B), and compared with the standard insecticides used for management in the Integrated Apple Production (IAP) system. Both formulations were applied at a rate of 1kg/ha on October 10, 2005 and December 13, 2005 using 300 and 1000 point sources/ha of SG+B and SAKG+B, respectively in experimental units of 7 ha. Adult male captures of B. salubricola and G. molesta were evaluated weekly in Delta traps with specific synthetic sex pheromone from October 10, 2005 to February 14, 2006. Damage to fruits was evaluated on November 21 and December 21, 2005, and January 25 and February 14, 2006. In the SPLAT treated experimental units a significant reduction was observed in the number of B. salubricola and G. molesta males caught in Delta traps compared to the experimental unit IAP. Damage by B. salubricola at harvest ranged from 1.63 to 4.75% with no differences between treatments, while damage by G. molesta was near zero in all experimental units. Mating disruption using SG+B and SAKG+B was sufficient to control B. salubricola and G. molesta with results equivalent to IAP guidelines. This technology is promising for management of both pests in Brazilian apple orchards with immediate reduction of 43% in the number of insecticide applications
The advantages of semiochemical-based attract and kill techniques in insect pest management.
Introduction: Semiochemicals (chemicals impacting insect behavior) have been employed in species-specific, ecologically friendly insect pest control strategies through a wide variety of mechanisms, many of which do not require the application of conventional insecticides. These include mating disruption?application of sex pheromones in such a way that male insects are unable to locate a female mate, reducing the size of the pest population in the treated area over time?mass trapping, and repellency. However, semiochemical attractants can also be used in combination with small amounts of chemical toxicants, a strategy called attract and kill (A&K)
Feromônios sexuais no manejo de insetos-praga na fruticultura de clima temperado.
bitstream/item/95271/1/Feromonios-ULTIMA-VERSAO-08-07-2013.pdf; bitstream/item/95273/1/Capa-Feromonios.pd
One-loop SYM-supergravity relation for five-point amplitudes
We derive a linear relation between the one-loop five-point amplitude of N=8
supergravity and the one-loop five-point subleading-color amplitudes of N=4
supersymmetric Yang-Mills theory.Comment: 17 pages, 2 figures; v2: very minor correction
Assessment of SPLAT formulations to control Grapholita molesta (Lepidoptera:Tortricidae) in a Brazilian apple orchard.
Mating disruption is a technique that uses synthetic copies of sex pheromones to control insect pests. We aimed to control Oriental fruit moth (OFM) Grapholita molesta (Busck) (Lepidoptera: Tortricidae) with formulations of SPLAT Grafo (SG) and SPLAT Grafo Attract and Kill (SGAK) in small (1 ha) apple (Malus domestica Borkh.) orchards. Our experiment was conducted in a commercial orchard with Gala trees (spacing 1.5 × 4.5 m) in Vacaria, Rio Grande do Sul State, Brazil. We evaluated the effect of four treatments on G. molesta population densities: a) SG at 1 kg ha-1 (300 point sources of 3.3 g each), b) SGAK at 1 kg ha-1 (1000 point sources of 1 g each), c) insecticides as recommended by Integrated Apple Production (IAP), and d) untreated control (no treatment). Specialized Pheromone and Lure Application Technology (SPLAT) treatments were applied on 1 August 2004 and reapplied after 120 d (1 December 2004). The treatment effect was evaluated by weekly counts of males captured in Delta traps baited with commercial synthetic sex pheromone lures (eight traps per treatment). We assessed fruit damage caused by G. molesta in eight replicates of 200 fruits each on 26 October, 30 November 2004, and 5 and 31 January 2005. Applying 1 kg ha-1 of SG and SGAK in August and December 2004 significantly reduced the number of male moths caught in Delta traps. Damage to fruits at harvest, however, did not differ significantly from the control. This indicates a decline in the efficacy of mating disruption when SG and SGAK are used to protect small areas (1 ha) under high Oriental fruit moth pressure
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