Search

Dioryctria sylvestrella( Lepidoptera: Noctuidae) is a serious pest of the Korean pine( Pinus koraiensis) which is the precious tree species in northeast China. It is a specialist feeder on the Korean pine and can`t complete its life circle on tree species other than Pinus koraiensis. Common pest control measures such as spraying insecticides are normally not effective because their larvae feed inside the pine cones and shoots. Once outbreak,more than 85% trees could be damaged,which might result in significant reduction in seed production. Until now,there is no efficient and environment friendly pest control method to reduce the economic losses caused by this serious pest insect. Macrocentrus sp. is a key larval parasitoid of D. sylvestrella and might play an important role in regulating its host population dynamics as a natural control agent. Chemical signals play a major role in the orientation of insects to mates and suitable hosts. In this paper,we describe the diurnal behavioral responses of the adult moths and their parasitoid wasps to P. koraiensis cones,shoots and branches by using a Y tube olfactometer. Volatiles released during day and night from cones,shoots and branches of healthy and D.sylvestrella larvae-damaged pine trees were collected and analyzed by GC-MS. The aim of the present study was to determine the diurnal pattern of volatiles released from cones,shoots and branches,and its potential effect on host-finding behavior of D. sylvestrella and the its parasitoid Macrocentrus sp..Y tube bioassay indicated that virgin,mated female moths and male moths responded strongly to volatiles released from the healthy pine cones and shoots during night. Mated females seemed also to respond to the larvae-damaged cones at night. Whereas the parasitic wasps( both sexes) were more responsive to volatiles released from D. sylvestrella larvae-damaged pine cones and shoots during the daytime. GC-MS analyses showed significant diurnal variations in volatile compositions and contents between healthy and damaged pine samples,and among the cones,shoots and branches,especially in the relative contents of major monoterpenes, including, α-Pinene, Camphene, β-Phellandrene β-Pinene, 3-Carene, Ocimene, Myrcene and D-limonene. D-limonene was only volatilized form lateral branches of P. koraiensis,and the response ratio for males,virgin and mated females of D. sylvestrella to lateral branches were significant lower than cones and tips. Thus,we assumed that D-limonene should play a special function on D. sylvestrella host location of the adult moths. This function would be an important reason of Dioryctria evading the lateral branchs of P. koraiensis. Some specific sequiterpenes such as Bornylacetate and Caryophyllene were present mainly from the D. sylvestrella larvae-damaged pine samples,which might function as repellent volatiles for the moth or attractant volatiles( synomone) for the parasitoid wasps. The host selection behaviors of D. sylvestrella and their parasitic wasps seemed to be regulated or influenced by the variations of monoterpene contents in the pine cones,shoots or branches. The exact functionality of these specific sesquiterpenes( individuals or in combinations) is not known; however,further study is surely needed to determine if these sesquiterpenes with or without monoterpenes might play a role in oviposition behaviors of both D. sylvestrella and their parasitoid wasps.

Maize emergence speed and the emergence rate relate to soil moisture and air temperature,and they largely determine the corn growth and yield.In order to obtain the relationships between seedling emergence speed,seedling rate of spring maize(Zea mays) and soil moisture and air temperature respectively,the experiments of water stress and by-stage sowing for spring maize were conducted at an agro-meteorological experiment station in the central part of Northeastern China.In an artificial rain-proof cover,4 water treatments(not drought,light drought,drought and severity drought) and 3 sowing treatments(early,middle and late) were set to create soil moisture variation and air temperature difference during the period from sowing to germination.And soil moisture,water amount for irrigation,rainfall,air temperature,the seedling stage and emergence rate were observed.The results showed that the relationships between soil moisture and emergence rate,period of emergence both were significantly quadratic function during the periods of sowing and emerging.Below field capacity,the greater soil moisture was,the faster the corn came out and the higher the emergence rate was.Soil drought delayed the period of emergence and decreased emergence rate.Low temperature slowed down the emergence,but had little effect on emergence rate.The equation of relationship between days from sowing to emerging(D),soil moisture(S) at a depth of 0 to 20 cm and average air temperature(T) was D=63.450—1.194S-1.442T.The equation of relationship between emergence rate(P),S and T was P=5.107 S +1.857 T-56.5.Combinational influence indexes of average soil moisture,effective soil water(H) and air temperature on maize emergence speed were that corn emerged quickly when 25%S21%,70 mmH45 mm and T18 ℃;it would emerge normally when 21%S18%,45 mmH 35 mm and 18 ℃T16.5 ℃;and it would emerge slowly when 18%S16%,35 mmH 25 mm and 16.5 ℃T15.5 ℃;and the emergence was postponed remarkably when S16%,H25 mm and T15.5 ℃.Germination rate depended mainly on soil moisture in this study.The highest germination rate(more than 95%) occurred when S85% and H50mm;the higher one(about 90%) when relative humidity was about 80% and 50 mmH40 mm;and the lower one when relative humidity was less than 70% and 50 mmH40 mm;and the one was less than 65% when relative humidity was less than 60% and H30 mm,and the serious drought happened.

The design principles and design methods are introduced for a InP-based Quantum Cascade Laser(QCL) with high power and short wavelength.According to the described ideal and real carrier transition paths,the active region designing trends and approaches to enhance the efficiency of the QCL are also proposed.The most advanced design methods,such as two phonon resonance design,nonresonant extraction design,strong coupling design,deep well design,shallow well design and short injector design are reviewed,respectively.The characteristics and advantages of each design method are discussed.With these highly advanced design approaches,the Wall-plug Efficiency(WPE) of the short wavelength QCL exceeds 50% at low temperature and room temperature,continuous wave operation surpasses 3 W and the maximum T0 and T1 reach 383 K and 645 K,respectively.As the most advanced working region,high power,advanced design methods make QCL unlimited usage in both military and civilian fields.Moreover,they could also be served as the highly efficient bandstructure pioneer design methods for other working regions.

Dry etching of InP material based on inductivity coupled plasma(ICP) was thoroughly studied,Cl2/Ar/H2 gas mixture was adopted,and the etching depth could reach 10 μm with a vertical and a smooth surface.The gas percentages of the total gas versus etching rate,and the applicable regions of Ni,SiO2,and the combination of Ni and SiO2 were studied,respectively.The regions of the effective etching rate and selectivity against Ni are 450~1 200 nm/min and 175~190,respectively.The choosing and fabrication approaches adopted are highly suitable for any semiconductor material based on ICP system.