【作者】 吴博；

【导师】 赵奎军；

【作者基本信息】 东北农业大学 ， 农业昆虫与害虫防治， 2008， 硕士

【摘要】 本文使用KC-2昆虫雷达,于2005-2007年每年的5—10月在渤海湾的北隍城岛上对夜间越海迁飞昆虫进行持续的观测。每天的21时至23时对当地地面至2000m高度的风温场进行探测。对昆虫在迁飞过程中聚集成层与风温场的关系进行分析,初步明确了昆虫在迁飞过程中的成层机制,并根据气象要素和成层的关系建立了成层模型。主要结果如下:1.成层现象的季节间变化和昆虫迁飞时期吻合,即迁飞高峰期成层现象出现的频率高。同时,一夜间不同时刻出现成层现象的次数变化与一夜间探照灯诱虫器内昆虫数量的变化也表现出一致性,这说明了成层是昆虫迁飞过程中的一个普遍现象。2.长岛上空越海迁飞昆虫的种类以鳞翅目、蜻蜓目、鞘翅目、脉翅目为主,其主要种类都是我国华北地区的农业害虫和天敌。棉铃虫、黏虫、甜菜夜蛾、蜻蜓、草蛉是主要迁飞种类。杨卷叶螟、玉米螟、宽胫夜蛾、朽木夜蛾、旋幽夜蛾、银纹夜蛾、银锭夜蛾、甘蓝夜蛾等这些次要的农业害虫也存在着迁飞的事实。蜻蜓、瓢虫、食蚜蝇、草蛉、步甲等都是害虫的天敌,诱虫数量上具有突增突减的特征,是明显的伴迁现象。他们是形成昆虫层的主要类群。3.成层现象出现的高度主要集中在500m以下,在200-300m高度处的成层现象最为常见;500m-1500m成层也较频繁;而1600m以上成层出现的次数较少。随着月份的增加,在500m以上出现昆虫层的频率逐渐增加。这是由于500m以上出现风速极值的频率随月份增加而增加,且昆虫喜欢聚集在风速极值出现的高度上成层。4.在5、6月份和9、10月份,成层与风向显著相关。5、6月份S和SW风出现成层的频率高,9、10月份N、NE、E风出现成层的频率高。这说明昆虫在春季北迁和秋季向南“回迁”的过程中会选择在适合其迁飞的风向出现的高度上聚集成层,从而利用有利的风向进行远距离的迁飞。而在7、8月份(昆虫夏季扩散时期),成层的出现与风向不相关,这段时期昆虫更喜欢聚集在风向切变出现的高度处成层。5.昆虫空中密度最大值出现的高度与风速最大值出现的高度显著相关,与逆温层顶高度不相关。当有风速极值或有风向切变(7、8月份)存在的时候,昆虫会聚集在风速极值或风向切变出现的高度上。只有当风向适合时,且风速极值或风向切变(7、8月份)和逆温层出现在同一个高度时,昆虫层才会出现在逆温层顶。6.利用成层和风温场的关系构建了昆虫的成层模型。昆虫在时间T、高度h上的成层概率P(T, h)=Max(Pd(T, WDh), Pd(T, Wh))×Pv(WSh)×Pt(th),其中Pd(T, WDh)为不同季节各个风向成层概率;Pd(T, Wh)为不同季节风向切变成层概率;Pv(WSh)为风速成层概率;Pt(th)为温度成层概率。经检验这个模型可以对昆虫层出现的情况做出较好的预测。更多还原

【Abstract】 The flight activities of insect migrating over the Bohai Sea during night were observed with an entomological radar (KC-2) at Beihuang from May to October of 2005 to 2007. The meteorological data, i.e. wind and temperature up to 2000 m above the ground level (AGL) were measured by balloon ascent over the period of 21 h to 23 h every night. The relationship between layering occurrence and meteorological causes was analyzed, thus the mechanism of layering was clear and a model for simulating the height of insect layers was made. The main points are as follows.1. The occurrence of layering phenomenon was coincident with the activities of insect migration through seasons, namely, the frequency of layering was higher during peak migrations of insect than during other time. In addition, the pattern of variation of layering frequency through time was similar to that of light-trap catches. These indicated that layering was a common phenomenon for the migratory insects during their long-distance migration.2. The insects migrating over the sea during night were mainly lepidopteran, odonata, beetles and neuropteran. Most of them were agricultural insect pests or natural enemies in northern China. Cotton bollworm, armyworm, beet armyworm, dragonfly, green lacewing predominated the migratory insects. Asparagus setaceus, Asian corn borer, mugwort cutworm, clover cutworm, bean semilooper, silver ingot semilooper, cabbage moth were less predominant insect pests, which were thought also migratory. The light-trap catches natural enemies, such as dragonfly, ladybug, hoverfly, green lacewing, and carabid beetles increased and decreased suddenly, which indicated the obvious accompanying migration.3. The altitudes of layers were generally below 500 m AGL, with the highest frequency of layering occurred at altitude of 200 - 300 m. The frequency of layering at altitude of 500 - 1500 m was also high. However, there was rare layering at altitude of above 1600 m. The frequency of layering at altitude of above 500 m increased as the month proceeding. This is because that the occurrence of maximum wind speed at these altitudes increased and insects tended to form layers at the height with wind maximum.4. The frequency of insect layering was significantly correlated with the wind direction in May, June, September, and October. The frequency of the insect layering formed in southern, southwestern winds was much higher than in other winds in May and June. The frequency of the insect layering formed in northern, northeastern, and eastern winds was much higher than in other winds in September and October. These indicated that insects tended to select suitable wind directions for flight during northward migration in spring and southward migration in autumn, so as to achieve the longest distance during migration. However, the frequency of the insect layering was not related to the wind direction in July and August. During of this period, insects tended to concentrate at the altitude with wind shear.5. The height where the maximum insect aerial density occurred was significantly related to the height where the maximum wind speed occurred,but not related to the height where the temperature inversion occurred. Insects tended to fly at the altitudes where the winds speed was maximum, or the altitudes with wind shear rather than the altitudes with temperature inversion in Jul and Aug. The insects tended to form layers at the top of temperature inversion only when the temperature inversion occurred at the same altitude as the wind maximum or wind shear occurred in suitable wind direction in July and August.6. Based on the relationship between insect layering and the wind and temperature, a model for estimating altitude of layering was established. At time T and height H, the probability of layeringP(T, h)=Max(Pd(T, WDh), Pd(T, Wh))×Pv(WSh)×Pt(th), where Pd(T, WDh), Pd(T, Wh), Pv(WSh) and Pt(th) was the layering probability function of the wind direction, the wind shear, the wind maximum, and the temperature, respectively. This model fitted our dataset well and could predict the altitudes of layering.更多还原