Yu Eric Yu, Gassmann Aaron J, Sappington Thomas W
Department of Entomology, Iowa State University.
Corn Insects & Crop Genetics Research Unit, USDA-ARS;
J Vis Exp. 2019 Oct 29(152). doi: 10.3791/59196.
The western corn rootworm, Diabrotica virgifera virgifera (LeConte) (Coleoptera: Chrysomelidae), is an economically important pest of corn in the northern United States. Some populations have developed resistance to management strategies including transgenic corn that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Knowledge of western corn rootworm dispersal is of critical importance for models of resistance evolution, spread, and mitigation. Flight behavior of an insect, especially over a long distance, is inherently difficult to observe and characterize. Flight mills provide a means to directly test developmental and physiological impacts and consequences of flight in the laboratory that cannot be obtained in field studies. In this study, flight mills were used to measure the timing of flight activity, total number of flights, and the distance, duration, and speed of flights taken by female rootworms during a 22-h test period. Sixteen flight mills were housed in an environmental chamber with programmable lighting, temperature, and humidity control. The flight mill described is of a typical design, where a flight arm is free to rotate about a central pivot. Rotation is caused by flight of an insect tethered to one end of the flight arm, and each rotation is recorded by a sensor with a time-stamp. Raw data are compiled by software, which are subsequently processed to provide summary statistics for flight parameters of interest. The most difficult task for any flight mill study is attachment of the tether to the insect with an adhesive, and the method used must be tailored to each species. The attachment must be strong enough to hold the insect in a rigid orientation and to prevent detachment during movement, while not interfering with natural wing motion during flight. The attachment process requires dexterity, finesse, and speed, making video footage of the process for rootworms of value.
西部玉米根萤叶甲，即Diabrotica virgifera virgifera（LeConte）（鞘翅目：叶甲科），是美国北部一种具有重要经济意义的玉米害虫。一些种群已对包括转基 因玉米在内的管理策略产生了抗性，这些转基因玉米能产生源自苏云金芽孢杆菌（Bt）的杀虫毒素。了解西部玉米根萤叶甲的扩散情况对于抗性进化、传播和缓解模型至关重要。昆虫的飞行行为，尤其是长距离飞行行为，本质上很难观察和描述。飞行磨提供了一种在实验室中直接测试飞行对发育和生理的影响及后果的方法，而这些是在田间研究中无法获得的。在本研究中，飞行磨被用于测量雌性根萤叶甲在22小时测试期内的飞行活动时间、飞行总次数以及飞行的距离、持续时间和速度。16个飞行磨放置在一个具有可编程照明、温度和湿度控制的环境舱中。所描述的飞行磨为典型设计，其中飞行臂可围绕中心枢轴自由旋转。旋转是由拴在飞行臂一端的昆虫飞行引起的，每次旋转由带有时间戳的传感器记录。原始数据由软件汇编，随后进行处理以提供感兴趣的飞行参数的汇总统计信息。任何飞行磨研究中最困难的任务是用粘合剂将系绳附着到昆虫身上，所使用的方法必须针对每个物种进行调整。附着必须足够牢固，以将昆虫保持在固定方向并防止在移动过程中脱落，同时又不干扰飞行过程中翅膀的自然运动。附着过程需要灵巧性、技巧和速度，因此拍摄根萤叶甲附着过程的视频很有价值。
