Using flight mills to measure flight propensity and performance of western corn rootworm, Diabrotica virgifera virgifera (LeConte)

Authors: YU, ERIC - Iowa State University; GASSMANN, AARON - Iowa State University; Sappington, Thomas

Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2018
Publication Date: 10/29/2019
Citation: Yu, E.Y., Gassmann, A.J., Sappington, T.W. 2019. Using flight mills to measure flight propensity and performance of western corn rootworm, Diabrotica virgifera virgifera (LeConte). Journal of Visualized Experiments. 152. https://doi.org/10.3791/59196.
DOI: https://doi.org/10.3791/59196

Interpretive Summary: Laboratory study of insect flight behavior commonly employ flight mills. Their use involves attachment of a tether to the insect which is then mounted on the flight arm of the flight mill. The flight arm rotates freely around a central pivot when the insect flies, triggering a sensor with each revolution. Revolutions with a time stamp are recorded by a computer. Although flight mills have been used by many researchers on many insect species for over 60 years, the process of attaching the tether to the insect is different for each species, can be a source of frustration for inexperienced students, and is often more art than science. In this paper we demonstrate by video how to attach a tether to the western corn rootworm. This insect is a serious pest of corn, and understanding its flight behavior is important in the contexts of both pest management and management of resistance to control measures. Tethering this insect can be particularly troublesome because of its waxy back and small size. Visually seeing how it is done will be helpful to other government, university, and industry scientists who would like to conduct flight experiments with this or other small insect pests.

Technical Abstract: 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 Bt corn. 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 long-distance is inherently difficult to observe and characterize. Flight mills provide a means to directly test developmental and physiological impacts on and consequences of flight in the laboratory that cannot be obtained in field studies. In this study, we used flight mills to measure the timing of flight activity, total number of flights, and the distance and duration 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 process of attachment requires dexterity, finesse, and speed, making video footage of the process for rootworms of particular value. Representative results comparing flight by females from two populations are presented.