迁飞过程中昆虫的行为:对风温场的适应与选择

本文综述了昆虫在迁飞过程中对大气物理环境的各种行为反应,有边界层气象的理论重新审视迁飞种群的时空分布,提出了“边界层顶现象”的概念。即边界层顶的低空逆温和低空急流为迁飞种群提供了最适宜的风温场,迁飞种群在边界层顶集聚成层,并通过定向理一步修饰其位移方位,表现出对风温场的主动选择能力和对大气结构和运动的高度复杂的适应性反应。进一步深化对“边界层顶现象”的认识,对迁飞性害虫的异地预测具有重要的理论意义     

追踪天使——雷达昆虫学30年

雷达昆虫学是一门新的学科分支。从它诞生起的30年来,英、美、澳、中四国的观测研究已初步阐明了昆虫在迁飞过程中的成层、定向、集聚等行为现象及其时空分布,揭示了大气结构和运动对昆虫迁飞的影响,为深化人们对昆虫迁飞行为机制的认识提供了许多令人耳目一新的画面;昆虫雷达技术也逐渐从研究走向实用,已经实现了对迁飞性害虫的长期、自动和实时监测。在全国建立VLR网并与GIS相结合,可望实现对我国重大虫灾的及时预警。     

昆虫雷达让我们看到了什么?

昆虫雷达的应用深化了人们对昆虫迁飞行为机制的认识。昆虫雷达让我们看到了弱小的昆虫主动起飞 ,以一定的速度爬升到巡航高度乘风远行 ,并对大气风温场表现出令人难以置信的适应和选择能力 ,通过成层 (边界层顶现象 )、定向和集聚等主动行为 ,最大限度地利用空气动力到达新的栖息地。这些全新的画面展示出远迁的昆虫并非完全被动的随风飘流者 ,而是一个个驾舟中流击水的舵手。     

昆虫迁飞行为的参数化

通过对雷达昆虫学研究和其他方法得到的研究成果的综合分析,提出一套昆虫迁飞行为参数化方案。即：起飞时间以日出日 晨昏朦影时 基准,降落时间依目标昆虫的迁飞牧场考具体取值;运行高度取边界层顶与目标昆虫飞行低温阈限所在高度之间的气流层。在运行方向取风向值并以目标昆虫的定中以修饰,运行速度与目标昆虫自身行速度的矢量和。这套方案可作为昆虫迁飞数值模拟的基础,为迁飞性害虫异地预测提供一种有效的工具 。     

昆虫迁飞行为及其调控机制

迁飞是昆虫长期适应资源与环境的季节性变化所形成的一种行为策略.迁飞昆虫不仅通过迁飞逃避不良环境,也因其极高的繁殖力确保种群在新的生境中实现快速增长甚至暴发成灾,对整个自然生态系统和农业生态系统影响甚大.本文首先基于部分迁飞概念,描述了迁飞型和居留型个体在形态、行为、生理上的差异,重点介绍了迁飞与生殖的耦合关系,以及诱导迁飞的外界环境因子,最后综述了昆虫迁飞行为调控的分子机制方面的研究进展.从感受不良环境信号到决定迁飞,从起飞、飞行、降落到决定继续迁飞或终止迁飞,这一系列过程受昆虫内分泌、表观等诸多因素的调控,但其背后的分子机制有待深入研究.     

基于两种轨迹模型的褐飞虱迁飞轨迹比较研究

异地预测是迁飞性害虫发生预测的重要内容,迁飞轨迹模拟和预测是能较好地反映害虫迁飞时空动态的一种异地预测方法。褐飞虱作为我国水稻生产上的一种重要迁飞性害虫,其迁飞轨迹的准确预报,可为其灾变预警和有效防控提供科学依据。为了比较选择一些准确性好、分辨率高、易于推广应用的害虫迁飞轨迹模型,选取2006年7月初发生在湖南省洪江市的一次褐飞虱重大北迁过程作为典型个例,运用中尺度天气研究和预报模式WRF,结合NCEP气象再分析数据,利用HYSPLIT和FLEXPART两种轨迹计算模式对褐飞虱迁飞轨迹进行模拟,并验证模型模拟和计算的准确度和精确度。研究结果表明:(1)WRF-HYSPLIT和WRF-FLEXPART两种轨迹计算模式在虫源地、迁飞路径(迁飞方位角和走向)、迁飞高度、迁飞速率和迁飞距离计算上总体趋势一致,但存在一定的差异,后者的起伏变化大于前者。(2)尽管两种耦合模式在调用WRF模式输出的预报场物理变量方面有很多相同之处,但WRF-FLEXPART耦合模式在运行计算过程中比WRF-HYSPLIT耦合模式多考虑了对流参数、地表胁迫和各种地形参数,因而能更全面地反映中尺度天气过程(特别是对流性天气过程)对昆虫起飞、空中飞行和降落的动力作用,也能更真实地反映地表物理过程、大气湍流结构和地形起伏对褐飞虱种群迁飞的影响。(3)从褐飞虱种群对生境和取食条件选择上看,两种模式模拟的各高度迁入种群的虫源区、迁飞路径和降落地都是合理的、准确的。但从褐飞虱迁出、空中飞行和降落所处的三维流场来看,WRF-FLEXPART模式轨迹走向与盛行气流方向的吻合度要明显高于WRF-HYSPLIT模式。(4)两种模式均可作为业务工具在迁飞性害虫测报中推广应用。     

昆虫迁飞的调控基础及展望

昆虫迁飞是在长期适应多变的环境过程中进化形成的一种行为对策,也是昆虫的种类和数量繁多,以及迁飞害虫经常暴发成灾的主要原因.昆虫迁飞行为的发生不仅受到外界环境因素的影响,而且受到本身生理因素的调控.目前,国内外对此类研究主要集中在生态环境、生理因素、行为学以及种群遗传学方面的调控机制.随着分子生物学技术的发展,昆虫迁飞行为发生的分子调控机制也越来越受到重视.在对国内外主要昆虫迁飞调控机制概述的基础上,对新的分子生物学技术在昆虫迁飞调控中的应用进行了探讨与展望.     

昆虫迁飞行为的参数化Ⅰ.行为分析

通过对雷达昆虫学研究和其他方法得到的研究成果的综合分析,提出一套昆虫迁飞行为参数化方案。即：起飞时间以日出日没及晨昏朦影时刻为基准,降落时间依目标昆虫的迁飞特性具体取值;运行高度取边界层顶与目标昆虫飞行低温阈限所在高度之间的气流层,运行方向取风向值并以目标昆虫的定向加以修饰,运行速度为风速与目标昆虫自身飞行速度的矢量和。这套方案可作为昆虫迁飞轨迹数值模拟的基础,为迁飞性害虫异地预测提供一种有效的工具     

稻纵卷叶螟(Cnaphalocrocis medinalis)迁飞的多普勒昆虫雷达观测及动态

在2007年7～9月江淮稻区稻纵卷叶螟大发生期间,利用多普勒昆虫监测雷达在南京市浦口区对稻纵卷叶螟成虫的迁飞活动进行了监测,结合大气风温场的数值模拟,研究了稻纵卷叶螟成虫的空中飞行参数和种群迁飞动态。结果表明：稻纵卷叶螟多选择在黄昏18：30以后大规模起飞,空中虫群密度在20：00～22：00时最大,迁飞过程可持续到次日5：00;稻纵卷叶螟主要选择在500m以下高度飞行。空中虫群具有聚集成层的现象,虫层多在100～500m高度之间形成,有时形成两个虫层,成层现象与低空急流关系密切,与温度没有直接关系。迁飞过程分析表明,浦口区的六（4）代稻纵卷叶螟在台风、副热带高压和江淮气旋的影响下,先后出现了多次迁入迁出过程。低压系统外围的下沉气流很可能是稻纵卷叶螟两次集中迁入的主要原因。     

北京多普勒天气雷达上的昆虫回波分析

【目的】为了解北京多普勒天气雷达上的昆虫回波信息,探索其在迁飞害虫监测预警中的应用。【方法】选取北京南郊观象台新一代天气雷达CINRAD-SA积累的晴空回波数据和风廓线雷达提供的风速风向数据,基于有关软件分析了昆虫回波的特点,讨论了降水等其他因素对昆虫迁飞的影响。【结果】新一代天气雷达可以探测到空中迁飞昆虫引发的后向散射回波,晴空回波日节律符合夜行性昆虫的朦影起飞和日出降落的行为特点,晴空回波出现的时期是3月至11月,中间有2个高峰期;晴空回波数量与风向关系密切,当天气系统合适时,晴空回波会出现成层和共同定向现象;此外,降水会中断昆虫迁飞。【结论】北京多普勒天气雷达可以探测昆虫迁飞,在迁飞性害虫监测预警及其综合防控工作中具有重大的潜在应用价值,今后农业部门在优先建立昆虫雷达网络的同时,应加强与气象部门合作,发挥天气雷达的补充作用,共同提高迁飞性害虫的监测预警水平。     

Brown planthopper Nilaparvata lugens was concentrated at the rear of the typhoon Soudelor in Eastern China in August 2015

Sometimes, extreme weather is vital for the population survival of migratory insects by causing sudden population collapse or outbreak. Several studies have shown that rice planthopper migration was significantly influenced by typhoons in eastern Asia. Most typhoons occur in the summer, especially in August. In August, brown planthopper Nilaparvata lugens (Stål) migrates northward or southward depending on wind direction, and thus typhoons can potentially influence its migration process and population distribution. However, this has not yet been studied. This paper reported a case study on the effects of Typhoon Soudelor on the summer migration of N. lugens in eastern China in 2015. The migration pathways of N. lugens were reconstructed for the period under the influence of a typhoon by calculating the trajectories and migration events in eight counties of the Yangtze River Valley region with ancillary information. Trajectory modelling showed that most migrants took short distance migrations (less than 200 km) under the influence of the Typhoon Soudelor. Numerous N. lugens migrants were concentrated and deposited at the rear of the typhoon during the last 5 days of Typhoon Soudelor on August 9–13 due to horizontal convergence, and this led to an outbreak population. These results indicated that the N. lugens population was redistributed by the typhoon in the summer and that the population dynamics at the rear of a typhoon should be kept under close surveillance. This study provided insight into migratory organisms adapting to atmospheric features.     

昆虫定向机制研究进展

许多昆虫具有定向运动的行为。对部分社会性昆虫和迁飞性昆虫定向行为的大量研究已经初步阐明太阳、地磁场、天体、风及地面标志物等都可能成为昆虫返巢和迁飞定向的线索。社会性昆虫具有对不同定向线索进行整合而实现精确导航的能力。日间迁飞性昆虫利用时间补偿太阳罗盘进行定向的机制亦已明确,但夜间迁飞昆虫的定向机制尚需深入研究。迁飞性害虫定向机制的明确将有助于判断害虫迁飞路径及降落区域,为迁飞害虫的准确预测提供科学依据。本文对昆虫的定向机制研究进展进行了综述。     

The 'aerial plankton' and atmospheric convergence

Airborne migration is one of the most common adaptations for surviving and exploiting habitat variability. One weather feature that airborne migrants sometimes encounter, convergence, has the potential to concentrate populations in localities where climatic conditions have made a habitat temporarily favourable. Studies of migratory insects have now begun to establish which of several forms of atmospheric convergence are most likely to affect population processes.     

NUMERICAL SIMULATION OF THE PATHWAYS OF MIGRATING INSECTS

Abstract  Based on boundary layer meteorology and behavioural ecology of insect migration, a numerical TRA model was established. The spatial and temporal resolutions of the standard meteorological data are far insufficient for insect migration studies; so, a one dimension TKE closure scheme (E-ε scheme) was adopted to simulate the wind and temperature profiles en route based on the conventional surface and 850 hPa wind and temperature data of Chinese National Meteorological Bureau. Then the migrating behaviour of insects was parameterized as some proper mathematical expressions to determine their timing and their flight height, speed and direction from the wind and temperature profiles simulated by the PBL sub-model, and so their flight pathways could be estimated by a simple algorithm. Finally, the hourly episodes of the airborne migrants were output which consists of the latitude, longitude and flying altitude. The TRA model was verified by mark-release-recapture studies of Mythimna separata, Loxostege sticticalis , and Agrotis ipsilon . The results suggest that the parameterizing scheme of migratory behaviour, the numerical simulation scheme of wind and temperature in PBL and the TRA procedure developed in this paper should be reasonable and feasible. This model provides a useful tool for inter-regional forecast of migratory insect pests.     

江西上犹2009、2010年南方水稻黑条矮缩病的毒源地分析

通过灯下诱虫情况调查、毒源地分析、轨迹模拟、ArcGIS技术以及天气学背景分析,阐释了2009、2010年江西省上犹县发现的南方水稻黑条矮缩病(SRBSDV)的供毒源地情况,以及白背飞虱Sogatella furcifera(Horváth)携毒的传递路径。结果显示:(1)通过对白背飞虱迁入上犹的虫源地与经鉴定的南方水稻黑条矮缩病发病区域的叠加分析,明确了传入上犹的毒源地分布于广东、广西、海南3省区境内。(2)西南低空急流及偏南气流是白背飞虱将我国南方的病毒远距离传送到上犹县境内的动力源。(3)白背飞虱随下沉气流和降雨在上犹境内的集中降落是SRBSDV在当地暴发的触发条件。     

Orientation Cues for High-Flying Nocturnal Insect Migrants: Do Turbulence-Induced Temperature and Velocity Fluctuations Indicate the Mean Wind Flow?

Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction.     

Radiotelemetric analysis of the effects of prevailing wind direction on Mormon cricket migratory band movement

During outbreaks, flightless Mormon crickets [Anabrus simplex Haldeman (Orthoptera: Tettigoniidae)] form large mobile groups known as migratory bands. These bands can contain millions of individuals that march en masse across the landscape. The role of environmental cues in influencing the movement direction of migratory bands is poorly understood and has been the subject of little empirical study. We examined the effect of wind direction on Mormon cricket migratory band movement direction by monitoring the local weather conditions and daily movement patterns of individual insects traveling in bands over the same time course at three close, but spatially distinct sites. Although weather conditions were relatively homogeneous across sites, wind directions tended to be more variable across sites during the morning hours, the period during which directional movement begins. Migratory bands at different sites traveled in distinctly different directions. However, we failed to find any evidence to suggest that the observed variation in migratory band movement direction was correlated with local wind direction at any time during the day. These results support the notion that the cues mediating migratory band directionality are likely to be group specific and that a role for landscape-scale environmental cues such as wind direction is unlikely.     

Optimal strategies for insects migrating in the flight boundary layer: mechanisms and consequences

Directed aerial displacement requires that a volant organism'sairspeed exceeds ambient wind speed. For biologically relevantaltitudes, wind speed increases exponentially with increasedheight above the ground. Thus, dispersal of most insects isinfluenced by atmospheric conditions. However, insects thatfly close to the Earth's surface displace within the flightboundary layer where insect airspeeds are relatively high. Overthe past 17 years, we have studied boundary-layer insects byfollowing individuals as they migrate across the Caribbean Seaand the Panama Canal. Although most migrants evade either droughtor cold, nymphalid and pierid butterflies migrate across Panamanear the onset of the rainy season. Dragonflies of the genusPantala migrate in October concurrently with frontal weathersystems. Migrating the furthest and thereby being the most difficultto study, the diurnal moth Urania fulgens migrates between Centraland South America. Migratory butterflies and dragonflies arecapable of directed movement towards a preferred compass directionin variable winds, whereas the moths drift with winds over water.Butterflies orient using both global and local cues. Consistentwith optimal migration theory, butterflies and dragonflies adjusttheir flight speeds in ways that maximize migratory distancetraveled per unit fuel, whereas the moths do not. Moreover,only butterflies adjust their flight speed in relation to endogenousfat reserves. It is likely that these insects use optic flowto gauge their speed and drift, and thus must migrate wheresufficient detail in the Earth's surface is visible to them.The abilities of butterflies and dragonflies to adjust theirairspeed over water indicate sophisticated control and guidancesystems pertaining to migration.