Chemosensory systems are considered to play an important role in host plant selection in herbivorous insects.However,few studies have focused on chemosensory proteins(CSPs)for aphid host-location mechanisms.The roles ...Chemosensory systems are considered to play an important role in host plant selection in herbivorous insects.However,few studies have focused on chemosensory proteins(CSPs)for aphid host-location mechanisms.The roles of CSPs in searching for different Poaceae species(wheat,barley,triticale,maize and sorghum)were tested in Rhopalosiphum padi,an important cereal pest.The olfactometer assays showed that R.padi responds to plant odors.Seven R.padi CSP genes were identified.Influence of aphid morph,tissue and starvation state on expression patterns of CSPs was evaluated.Expression levels of CSPI,CSP4,CSP5 and CSP6 in winged aphids were significantly higher than those in wingless ones.Transcription levels of four genes(CSPI,CSP4,CSP5 and CSP6)were relatively higher in the head with antennae,and the four genes tended to be upregulated follow ing starvation.Silencing of three CSPs(CSP4,CSP5 and CSP6)altered aphid host-location behavior in response to the five different host plants tested.Three volatile compounds of host plants(octanal,[E]-2-hexenol and linalool)have signif-icant attraction to winged R.padi according to the four-arm olfactometer tests.Molecular docking predicted hydrogen bonding sites which played key roles in the binding of CSP4,CSP5 and CSP6 with volatile compounds.Knockdown of CSP4 or CSP5 significantly decreased the staying time of R.padi in the arms with octanal.However,knockdown of CSP6 could not affect the response of R.padi to octanal.These results bring evidence for the involvement of three CSPs in R.padi host-location behavior.展开更多
Small brown planthopper, Laodelphax striatellus （Fall6n） numbers usually drop sharply in the summer and revive quickly in the autumn. However, it is unclear whether and how the high temperature plays a role in this ...Small brown planthopper, Laodelphax striatellus （Fall6n） numbers usually drop sharply in the summer and revive quickly in the autumn. However, it is unclear whether and how the high temperature plays a role in this process. The effects of durations of heat exposure （33~C） on life-history traits were examined here. Exposure of adults for 1 day during the oviposition stage led to a very low survival of nymphs. The average longevity ofL. striatellus exposed for 1-31 days from oviposition was significantly longer than that of the control （27℃）. Short-term （1-5 days） heat exposure of the third instar nymphs did not significantly influence eclosion, but exposure of the fourth instar nymphs significantly increased eclosion. Lifespan from egg to adult was significantly lengthened when the third instar nymphs were exposed to heat for 2-15 days, or the fourth instar were exposed for 10 days. The preoviposition period was prolonged by heat exposure of the third or fourth instar nymphs. Short-term heat exposure of less than 3 days of the third or fourth instar nymphs did not restrict fecundity, but when the exposure duration exceeded 5 days the total eggs per female and hatchability decreased. Exposure to high temperature increased the brachypter rate of adults. In summary, low survival and slowing development under heat exposure resulted in population decline in the summer, and the relatively high fecundity and brachypter rate led to quick revival in autumn. Temperature in the summer determines the rise and fall in numbers ofL. striatellus.展开更多
针对典型跨声速民用客机的机翼/机身/平尾构型开展了基于离散伴随技术的气动外形优化设计方法研究,并采用自由型面变形(FFD)技术在优化设计过程中进行平尾的整体偏转,以实现最终设计结果全机俯仰力矩配平。采用基于雷诺平均Navier-Stoke...针对典型跨声速民用客机的机翼/机身/平尾构型开展了基于离散伴随技术的气动外形优化设计方法研究,并采用自由型面变形(FFD)技术在优化设计过程中进行平尾的整体偏转,以实现最终设计结果全机俯仰力矩配平。采用基于雷诺平均Navier-Stokes(RANS)方程的离散伴随技术求解气动参数对设计变量的梯度,使梯度求解计算量与设计变量个数实现解耦,提高了优化效率。应用FFD技术对全机构型进行整体参数化,可通过FFD控制体控制机翼外形的变化以及平尾偏转,在实现机翼优化设计的同时通过偏转平尾来进行力矩配平,避免了单独优化机翼外形可能带来的额外配平阻力。采用序列二次规划算法进行基于梯度的优化设计并处理大规模的约束条件。以Drag Prediction Workshop IV Common Research Model作为初始构型进行了有/无力矩配平约束的优化设计,并在优化过程中施加升力约束以及几何约束。算例结果表明,优化后的气动外形显著改善了机翼表面压力分布,消除了激波,在力矩配平约束下的算例中,通过平尾的偏转实现了俯仰力矩配平下的机翼优化设计。展开更多
基金the National Natural Science Foundation of China(grant nos.31972263,31901878 and 31772160)China Postdoctoral Science Foundation(grant no.2019M653773)。
文摘Chemosensory systems are considered to play an important role in host plant selection in herbivorous insects.However,few studies have focused on chemosensory proteins(CSPs)for aphid host-location mechanisms.The roles of CSPs in searching for different Poaceae species(wheat,barley,triticale,maize and sorghum)were tested in Rhopalosiphum padi,an important cereal pest.The olfactometer assays showed that R.padi responds to plant odors.Seven R.padi CSP genes were identified.Influence of aphid morph,tissue and starvation state on expression patterns of CSPs was evaluated.Expression levels of CSPI,CSP4,CSP5 and CSP6 in winged aphids were significantly higher than those in wingless ones.Transcription levels of four genes(CSPI,CSP4,CSP5 and CSP6)were relatively higher in the head with antennae,and the four genes tended to be upregulated follow ing starvation.Silencing of three CSPs(CSP4,CSP5 and CSP6)altered aphid host-location behavior in response to the five different host plants tested.Three volatile compounds of host plants(octanal,[E]-2-hexenol and linalool)have signif-icant attraction to winged R.padi according to the four-arm olfactometer tests.Molecular docking predicted hydrogen bonding sites which played key roles in the binding of CSP4,CSP5 and CSP6 with volatile compounds.Knockdown of CSP4 or CSP5 significantly decreased the staying time of R.padi in the arms with octanal.However,knockdown of CSP6 could not affect the response of R.padi to octanal.These results bring evidence for the involvement of three CSPs in R.padi host-location behavior.
文摘Small brown planthopper, Laodelphax striatellus （Fall6n） numbers usually drop sharply in the summer and revive quickly in the autumn. However, it is unclear whether and how the high temperature plays a role in this process. The effects of durations of heat exposure （33~C） on life-history traits were examined here. Exposure of adults for 1 day during the oviposition stage led to a very low survival of nymphs. The average longevity ofL. striatellus exposed for 1-31 days from oviposition was significantly longer than that of the control （27℃）. Short-term （1-5 days） heat exposure of the third instar nymphs did not significantly influence eclosion, but exposure of the fourth instar nymphs significantly increased eclosion. Lifespan from egg to adult was significantly lengthened when the third instar nymphs were exposed to heat for 2-15 days, or the fourth instar were exposed for 10 days. The preoviposition period was prolonged by heat exposure of the third or fourth instar nymphs. Short-term heat exposure of less than 3 days of the third or fourth instar nymphs did not restrict fecundity, but when the exposure duration exceeded 5 days the total eggs per female and hatchability decreased. Exposure to high temperature increased the brachypter rate of adults. In summary, low survival and slowing development under heat exposure resulted in population decline in the summer, and the relatively high fecundity and brachypter rate led to quick revival in autumn. Temperature in the summer determines the rise and fall in numbers ofL. striatellus.
文摘针对典型跨声速民用客机的机翼/机身/平尾构型开展了基于离散伴随技术的气动外形优化设计方法研究,并采用自由型面变形(FFD)技术在优化设计过程中进行平尾的整体偏转,以实现最终设计结果全机俯仰力矩配平。采用基于雷诺平均Navier-Stokes(RANS)方程的离散伴随技术求解气动参数对设计变量的梯度,使梯度求解计算量与设计变量个数实现解耦,提高了优化效率。应用FFD技术对全机构型进行整体参数化,可通过FFD控制体控制机翼外形的变化以及平尾偏转,在实现机翼优化设计的同时通过偏转平尾来进行力矩配平,避免了单独优化机翼外形可能带来的额外配平阻力。采用序列二次规划算法进行基于梯度的优化设计并处理大规模的约束条件。以Drag Prediction Workshop IV Common Research Model作为初始构型进行了有/无力矩配平约束的优化设计,并在优化过程中施加升力约束以及几何约束。算例结果表明,优化后的气动外形显著改善了机翼表面压力分布,消除了激波,在力矩配平约束下的算例中,通过平尾的偏转实现了俯仰力矩配平下的机翼优化设计。
