New and emerging insect pest and disease threats to forest plantations in Vietnam

The planted forest area in Vietnam increased from 3.0 to 4.4 million hectares in the period 2010–2020, but the loss of productivity from pests and diseases continues to be a problem. During this period, frequent and systematic plantation forest health surveys were conducted on 12 native and 4 exotic genera of trees as well as bamboo across eight forest geographic regions of Vietnam. Damage caused by insects and pathogens was quantified in the field and laboratory in Hanoi. The threats of greatest concern were from folivores (Antheraea frithi, Arthroschista hilaralis, Atteva fabriciella, Hieroglyphus tonkinensis, Lycaria westermanni,Krananda semihyalina, and Moduza procris), wood borers (Batocera lineolata, Euwallacea fornicatus, Tapinolachnus lacordairei, Xyleborus perforans, and Xystrocera festiva), sap-sucking insects (Aulacaspis tubercularis and Helopeltis theivora) and pathogens (Ceratocystis manginecans, Fusarium solani, and Phytophthora acaciivora). The number of new and emerging pests and pathogens increased over time from 2 in 2011 to 17 in 2020, as the damage became more widespread. To manage these pests and diseases, it is necessary to further invest in the selection and breeding of resistant genotypes, improve nursery hygiene and silvicultural operations, and adopt integrated pest management schemes. Consideration should be given to developing forest health monitoring protocols for forest reserves and other special-purpose forests

Management of needle-eating caterpillars associated with Pinus massoniana and P. merkusii in Vietnam

Pine tussock moth (Dasychira axutha Collenette (Lymantriidae)) and masson pine caterpillar (Dendrolimus punctatus Walker (Lasiocampidae)) cause serious damage to Pinus massoniana and P. merkusii plantations in Vietnam. An integrated pest management (IPM) program is required to control these pests. Therefore, this study was undertaken to identify damage thresholds and to evaluate control options for implementing IPM in the Northeast and North Central regions of Vietnam. Three damage thresholds were considered: 50% loss of leaf area. Control options were manual collection of eggs and pupae and the use of light traps and biological agents. An initial IPM model was developed for each pest and these gave control efficacies of 82.4% (Da. axutha on P. massoniana) and 77.8% (De. punctatus on P. merkusii). Six extended IPM models were undertaken by forest companies giving pest control efficacies of 79.2%–85.9%. The collection of pine resin provides an important source of income to local communities and the resin yield in the IPM models increased by 20.9%–22.7% compared to untreated control plots. The IPM protocols would help in developing policies that promote a more sustainable management of forest pests in Vietnam, thus reducing dependence on the use of insecticides of environmental and public health concerns

Effects of current density on the formation and microstructure of Sn–9Zn, Sn–8Zn–3Bi and Sn–3Ag–0.5Cu solder joints

The formation and growth of intermetallic compounds (IMCs) between lead-free solder alloys and Cu substrate were investigated. Cu6Sn5 IMC was formed in the Sn–3Ag–0.5Cu solder joint, whilst Cu5Zn8 IMC was formed in the Sn–9Zn and Sn–8Zn–3Bi solder joints after soldering. After exposure to a current density of 500 A/cm2 and 100 °C for 120 h, a sub-layer was detected in the Sn–3Ag–0.5Cu solder joint and this was identified as IMC Cu3Sn. The growth of the IMCs increased with increasing current density and was found to be faster at the anode side. Under the same testing conditions, the results showed that the growth rate or the thickness of the IMCs was highest in Sn–9Zn, followed by Sn–8Zn–3Bi, and the least being in Sn–3Ag–0.5Cu. The microstructure of Sn–3Ag–0.5Cu solder joint was observed to exhibit changes under exposure to current, whilst the microstructure of the Sn–9Zn and Sn–8Zn–3Bi solder joints remain unchanged, except for the increase in IMCs thickness

Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Two major methods to study them are the α resonant scattering, and direct measurements of (α,p) reactions using an active or inactive helium gas target. Among the recent studies at CRIB, the measurement of 7Be+α resonant scattering is discussed

Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Two major methods to study them are the α resonant scattering, and direct measurements of (α,p) reactions using an active or inactive helium gas target. Among the recent studies at CRIB, the measurement of 7Be+α resonant scattering is discussed

Studying astrophysical reactions with low-energy RI beams at CRIB

Studies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the α resonant scattering with 7Li and 7Be beams. This study is related to the astrophysical 7Li/7Be(α,γ) reactions, important at hot p-p chain and νp-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the 18F(p, α)15O reaction at astrophysical energies via the three body reaction 2H(18F, α15O)n. The 18F(p, α) 15O reaction rate is crucial to understand the 511-keV γ-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time

Studying astrophysical reactions with low-energy RI beams at CRIB

International audienceStudies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the alpha resonant scattering with ^7Li and ^7Be beams. This study is related to the astrophysical ^7Li/^7Be(alpha,gamma) reactions, important at hot p-p chain and nup-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the ^18F(p, alpha)^15O reaction at astrophysical energies via the three body reaction ^2H(^18F, alpha^15O)n. The ^18F(p, alpha) ^15O reaction rate is crucial to understand the 511-keV gamma-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time

Study of ?? cluster structure in 22Mg

The ??-cluster structure in the nuclei has been investigated for the perspective of nuclear structure. Contrary to the case of the 4N nuclei with N = Z, the experimental evidences of the clustering structures for the proton-rich systems are still lacking information. In order to study the interesting proton-rich 22Mg radionuclide, the 18Ne(??,??)18Ne elastic scattering will be measured at the Center for Nuclear Study Radioactive Ion Beam Separator of the University of Tokyo. By comparing the experimentally-obtained excitation function with theoretical R-matrix calculations, the resonance parameters of the 18xNe+?? system will be provided in the energy range 1MeV < Ec.m. < 12.4MeV.clos