DOI: 10.5061/dryad.j3tx95xqt
title: Female moths call in vain: Streetlights diminish the promise of mating

description: Artificial light at night has increased strongly in recent decades and is
 now affecting moths, a key contributor to pollination networks. The global
 shift to light-emitting diode (LED) streetlights changes the nocturnal
 light environment even further, especially because of their high
 variability in spectrum and intensity. To date, the impact on mating
 success of moths is only little  known, making it essential to
 investigate their behavioural responses. We recorded the flight behaviour
 of male moths (Sphinx ligustri) using a symmetrical flight tunnel. Two
 different light environments with a female positioned on one side of the
 tunnel were used to test the effect of different LEDs (1800K Amber, 2200K
 Warm white, 3900K Neutral white) and intensities (0.05 lux, 150 lux, 370
 lux, 590 lux) on arrival location, flight duration, and direction changes
 of males. We have created two different light habitats within the tunnel.
 A homogeneous light environment, with equal light on both sides of the
 tunnel, and a heterogeneous light environment, with light only on one
 side. In both habitats, the flight behavior of male moths was tested in
 the presence of females. To test whether mating behavior was impaired, a
 female was placed on only one side of the tunnel. In the heterogeneous
 habitat, the opposite side of the light was used to create a conflict.
description: We used a flight tunnel to observe and analyse the response of
 male moths (<em>Sphinx ligustri </em>L., Lepidoptera,
 Sphingidae) to different light stimuli. This flight tunnel consisted of
 plexiglass and had a total length of 3.50 m with an inner edge length of
 30 x 30 cm. A sliding door enabled us to position the moth in the middle
 of the tunnel. On top of each end, opaque boxes were positioned that
 contained the different light sources as well as a hook to add a cage with
 a female. These boxes had an opening of 20 x 20 cm to connect them with
 the flight tunnel. To prevent males from entering these boxes, the opening
 was covered with Gauze (Nobamull, Danz GmbH u. Co KG). To exclude any
 impact of the room, all non-white or reflective surfaces were covered with
 white cloths, creating a uniform environment around the flight
 tunnel. We tested three different light-emitting diodes
 (LEDs) provided by Osram (TRILUX GmbH & Co. KG): 1. Amber 1800 K
 (<em>λ max = 596 nm)</em> with almost no blue light
 components, 2. Warm white 2200 K (<em>λ max = 615 nm</em>)
 with a small proportion of blue in the light spectrum, specially developed
 to be particularly insect-friendly streetlight and still achieve a good
 colour effect, and 3. Neutral white 3900 K
 (<em>λ max = 444 nm</em>) with a high proportion of blue. The
 spectra of all LEDs were measured with a high-sensitivity spectrometer
 (Ocean Optics Maya2000 PRO; Figure 1b). Light intensity was measured in a
 distance of 50 cm directly below the light source using a luxmeter (RS Pro
 ILM Light Meter 1337). For the experiments, we use a
 species from the Sphingidae family, which are primarily nocturnal or
 crepuscular and are among the most important pollinators among moths
 (Winfree et al., 2011). <em>Sphinx ligustri</em> are robust,
 good fliers that have been reliably attracted to females in other
 experiments (Storms<em> et al.</em>, 2022). The<em>
 </em>pupae were stored during winter in the refrigerator at a
 temperature of 5°C without any light and removed between four and six
 weeks before the experiment. For hatching, the pupae were exposed to
 indirect daylight in a natural day-night rhythm. To prevent mating, the
 light pollution naïve males and females were kept separately in a uniquely
 labelled plastic bottle. During the day, the plastic bottles were not
 covered lightproof to maintain with daylight the natural rhythm. All
 experiments were carried out at night. Before experiments, all moths were
 fed under red light (Storm 400 Headlamp, Black Diamond Equipment Europe
 GmbH) with sugar solution (2M) to ensure they were not hungry. Afterwards,
 males were placed beneath separate metal tins standing on small wooden
 boards to enable easy transportation to the release platform within the
 flight tunnel. Furthermore, the tins ensured that the moths could rest for
 at least one hour before experiments in complete darkness and the
 experimenter was unaware of their body alignment in relation to the flight
 tunnel at the beginning of a trial. A virgin female older than two but
 younger than seven days was placed in a small cage covered with gauze.
 This cage was positioned in one of the two opaque boxes that could be
 easily switched from one side to the other. During all experiments, the
 position of the female was swapped after half of the males were tested. To
 ensure that all pheromones were removed before the next trials started,
 the entire tunnel was cleaned with ethyl alcohol and both, the tunnel as
 well as the room were ventilated. We performed a series of experiments to
 investigate the behaviour of male moths responding to various stimuli in
 two different light habitats. 
 A total of 38 male moths were used for all
 experiments. Each moth had only one flight attempt per night. If the trial
 was cancelled, the experiment was repeated the following night. As long as
 the individuals were able to fly the aim for each was to successfully
 complete all experiments once if possible (3 to 12 were achieved). Missing
 flights were replaced by individuals that hatched later. The order of the
 experiments per animal was randomized to avoid a possible effect of the
 age. To exclude a room bias, the sides were swapped for each experiment
 after half of the flights. The male moth beneath the metal tin was placed
 in the middle of the tunnel on a little starting platform (9 x 9 cm,
 height 5 cm). Once placed, the metal tin was removed to release the male
 in a randomised orientation. At this moment, observation of behaviour
 started and was recorded using an ethogram in BORIS (Friard &
 Gamba, 2016). Parameters recorded were flight duration (in seconds from
 flight start to end of flight), change in flight direction (we considered
 a change of &gt;180° to be a change in direction, indicating that an
 individual flew the opposite direction compared to the previous
 direction), intermediate stops and destination. One trial was completed
 when the male moth reached a pre-defined line, namely the transition from
 the tunnel to the last segment of the tunnel with the opaque box on top.
 If a male moth did not arrive on one side of the tunnel within 20 minutes
 or stopped its flight somewhere else in the tunnel, the trial was
 cancelled. All experiments were performed at approximately 25°C.
description: # **Female moths call in vain: Streetlights diminish the promise of
 mating** [https://doi.org/10.5061/dryad.j3tx95xqt
 ](https://doi.org/10.5061/dryad.j3tx95xqt) ## Description of the data and
 file structure \**Storms, M., Degen, T., Degen, J. ** **Female moths call
 in vain: streetlights diminish the promise of mating. *Ecological
 Entomology*** **Data_Storms.zip** **Data used to analyze arrival location,
 flight duration and direction changes of male moth in a flight tunnel.**  
 **Author(s)** Mona Storms Biocenter of the University of Würzburg,
 Würzburg, Germany
 [mona.storms@uni-wuerzburg.de](mailto:mona.storms@uni-wuerzburg.de) Tobias
 Degen Biocenter of the University of Würzburg, Würzburg, Germany
 [tobias.degen@uni-wuerzburg.de](mailto:tobias.degen@uni-wuerzburg.de)
 Jacqueline Degen Biocenter of the University of Würzburg, Würzburg,
 Germany
 [jacqueline.degen@uni-wuerzburg.de](mailto:jacqueline.degen@uni-wuerzburg.de) ### Files and variables #### File: Data\_Storms.zip.zip **Description:**  Data.csv Keynotes.txt **File descriptions** Data.csv - Data of each flight of the male moths. Keynotes.txt - List of all column names from Data.csv and their meaning or explanation of the variables. **Description of all the variables in the file "Data.csv"** | variables | units | description | | :-------------------- | :---------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Experimentart | Categorical | Type of Experiment. "W + L gegen L" & "W gegen D" equals a homogeneous environment. "W gegen L" equals a heterogenous environment | | LED | Kelvin | Correlated Color Temperature (CCT) in Kelvin. "1800" = Amber, "2200" = Warm white, "3900" = Neutral white | | Lux | Lux | Light intensity in lux. "0.05" = dim light, "150" = low intensity, "370" = medium intensity, "590" = high intensity | | Date | Date | Date of the flight trial | | Time | Time | Time of the release | | Subject | Number | Identification number of the individual males | | Richtungswechsel | Count | Counted number of direction changes within one flight trial | | Flightduration | Seconds | Duration of the whole flight trial in seconds, from lift off till reaching arrival location. Seconds and milliseconds are separated by a dot. When importing the csv, make sure that the flight time is displayed correctly. Example: Subject 10 with Date 5/28/2022 and Time 00:15:51 had a flight duration of 2 seconds and 377 milliseconds | | Anzahl Zwischenstopps | Count | Number of intermediate stops within the flight duration | | Ende\_Ort | Categorical | Arrival location of the moth. "Box mit Weibchen" = Female side, "Andere Box" = Dark side for heterogeneous environment and side with light and without female for homogeneous environment, "Irgendwo" = somewhere in the flight tunnel, "Dunkel" = Side without female for dim light in homogeneous habitat, "NA" = No departure from the release site |