A Simple Flight Mill for the Study of Tethered Flight in Insects

The overall goal of this flight mill device is to record flight behavior of insects under controlled conditions in the laboratory. So this method can help answer key questions in behavioral ecologies, such as what conditions stimulate beha dispersal or migratory behavior in insects compared to other flight mills. This device is relatively inexpensive and easy to assemble and build, and that makes it a great device for labs that aren't specialized in the study of insect flight behavior.

Though this method can provide insight into basic insect biology. It can also be applied to the control of pest insects by informing integrated pest management strategies. The construction and assembly of the flight mill is described in the protocol text.

The acrylic plastic support structure is assembled by sliding the five horizontal shelves into the slots in the two outside walls and the central wall resulting in a structure with eight individual cells each containing a magnetic pivot and an IR sensor allowing for eight individuals to be flown at the same time. The pivot arm to which the insects are tethered can be constructed with different materials to accommodate a variety of sizes and morphologies of insects. The IR sensors are fixed to the external sides of each cell using reusable adhesive putty, allowing the sensor to extend into the cell through the openings.

Cut into the external vertical wall supports a simple circuit built on a solderless breadboard connects input from the IR sensor to the data logger. Two resistors of 180 ohms and 2.2 kilo ohms respectively are connected on the input and output of the IR connection on the breadboard and placed in alternate rows along the breadboard to minimize drops in the voltage signal during recording for multiple sensors to begin the tethering procedure, place a small foil flag at the end of the un bent end of the pivoting arm. This will maximize disruption of the IR beam in the sensor and act as a counterweight.

Depending on the experimental insect size and cuticle area available for attachment, the insect is attached to an insect pin with hot glue or non-toxic skin glue if required. The kudzu bugs used in this demonstration do not require the skin glue mold. A small amount of adhesive around the rounded tip of an entomological pin gently apply on the pro noum area of the insect.

This procedure is suited for insects with a hard or soft cuticle that is not hairy. Insert the pin with the insect attached into the bent end of the pivoting arm assembly. To begin the flight trial, suspend the pivoting arm between the magnets and get the insect flying.

The appropriate software for the data logger is used for recording the flight trial data here, the Windex software that comes with the data queue. Data logger is used. Open the instrument hardware manager.

Select the data logger from the popup list and press Start Wind Act. A new window will open and the input signal from each sensor will be shown. Select the desired sampling frequency at which the data logger reads and displays the sensor's output.

The sampling frequency will depend on the insects flight speed. However, sampling frequencies ranging between 30 and 45 hertz will be fast enough to capture the flight of small to medium sized insects. Press CTRL F four.

To start a recording session. Select the destination path of the recording file in the first pop-up window. Choose and enter the appropriate length of time to record flight for the particular insect and experiment in the second pop-up window.

Once the recording time has elapsed, press control S to finalize the recorded file. After the flight trial has ended, remove the tethered insect. The quality of the recording should be checked prior to data analysis.

Open the recorded flight track and select a voltage channel. Press CTRL T to open a pop-up window with the voltage statistics for each channel. Ensure that no large drops in minimum value resulted from voltage drops across the circuit.

A high quality recording of a flight event has no voltage drops in the recorded signal. In contrast, if a flight event has voltage drops in the recorded signal, discard any channels in which the difference between the channel average and minimum voltage is greater than 0.1 volts. Save the file in a star CSV format.

Go to file, save as and in the popup window, select spreadsheet, print CSV in the spreadsheet, comments popup window, select relative time, and deselect all the other options. Click okay to save the file. Subsequently, the flight data is analyzed using the Python script provided in the appendix.

These can be edited in accordance with the experimental settings as detailed in the protocol. Text representative flight data from the burying beetle nigro forest Velois show that individual variation in flight behavior is easily recognized. One individual flew continuously for about three hours after the start of the trial and then flew periodically at high speed throughout the rest of the trial.

In another individual, the flight activity is characterized by a widespread of flying bouts in the first four hours of recording, after which its activity becomes almost periodical. This individual also never flew at the high speed seen in the first individual. Note the difference in scale on the Y axis of the two graphs.

Another representative example was obtained using the milkweed bug on cap pelus fasciatus. In this study, the recording time was set to one hour in order to characterize females as migrants or residents. This recording is typical of the type of flight behavior seen in a migrant female migratory individuals fly at a relatively steady speed over long periods of time.

In contrast, resident females fly at lower speeds and flight bouts only Last a short time. Note the difference in scale on the x-axis of the two graphs. The biggest challenge of this protocol is customizing the device and software for your study species.

So once you've collected your flight data, your insects can be removed from the flight mill and used to collect correlated life history data such as Vic Kennedy or lifespan. So now you should have a good understanding of how to collect and analyze flight behavior from insects under controlled conditions.