Temperature during pupal development affects hoverfly developmental time, adult lifespan and wing length

Authors:
Klára Daňková
Charles University, Prague, Czech Republic
klara.dankova@atlas.cz

Sarah Nicholas
Flinders University, Adelaide, Australia
sarah.nicholas@flinders.edu.au

Karin Nordström*
Flinders University, Adelaide, Australia
Uppsala University, Uppsala, Sweden
karin.nordstrom@flinders.edu.au

*corresponding author

Description:

This ReadMe file describes the structure of the data folder that accompanies publication Daňková et al. 2022 focusing on effect of the rearing temperature on activity, eclosion rate, pupal duration, morphometrics (body size, wing size, wing:thorax ratio, coloration), survival and weight gain of a cosmopolitan pollinator species, hoverfly Eristalis tenax (Diptera, Syrphidae).

Units and date format:
Temperature units: °C (Celsius)
Unit system: metric
Date format: DD/MM/YYYY

Structure

1_Raw_data
1a) Raw_data_activity (1 folder with 10 text files)
1b) Raw_data_morphometry_photos (1 folder with 3 subfolders containing photos)

2_Processed_data
2a) "final_data_activity.csv"
2b) "final_data_pupal_duration.csv"
2c) "final_data_eclosion_rate.csv"
2d) "final_data_morphometry.csv"
2e) "final_data_survival.csv"
2f) "final_data_weight.csv"

Detailed descriptions:

1_Raw_data

1a) Name: Raw_data_activity
Description: We provide our data on hoverfly activity in two forms: raw (10 text files in "1_Raw_data" folder) and processed (spreadsheet called "final_data_activity.csv" in "2_Processed_data" folder).
The "Raw_data_activity" folder contains raw data of hoverfly activity obtained right from Locomotor Activity Monitor LAM25 (TriKinetics Inc, Waltham, MA USA). Files are in ".txt" format, named "activity_TestingTemperature_StartDate(DD.MM.)_EndDate(DD.MM.)_Year.txt". The "testing temperature" stands for an ideal temperature [°C] in the climabox during the experimental session (12 °C, 17 °C or 23 °C -- please note that "RT" stands for 23 °C and "18" stands for 17 °C). Each row of the ".txt" files contains following information: minute of measuring, date, time, 7x columns recording technical information (outputs of light sensors etc.), 24x columns recording activity of individual hoverflies in each of the 24 glass tubes [counts/minute], 8x empty columns (this corresponds to the bottom row of 8 glass tubes that was intentionally left empty due to higher error rate in measuring).
LAM25 is a device in which the hoverflies were individually placed in horizontal glass tubes, sealed on both sides with a cotton ball with water, pollen and honey. Additional water was added to the cotton balls twice daily (before 9:00 and after 16:00) by a Pasteur pipette to prevent drying out. Each time the hoverfly crossed the center of the tube, it would break an infrared beam, and this would be counted as an activity measurement. The hoverflies were kept in the Locomotor Activity Monitoring system (LAMS) for approximately 48 hours, starting in the morning, and the average activity between 10:00 and 16:00 on the second day of recording was used for quantification. We quantified the mean activity at 12°C, 17°C or 23°C by placing the LAMS in wine cooler fridges or at room temperature, under a 16 hour light: 8 hour dark cycle. Sometimes a hoverfly would remain stationary in the middle of the tube for extended periods of time, continuously breaking the beam. To avoid this giving erroneously high activity measurements, all measurements indicating more than 10 crossings per minute were replaced with a 1 and all non-null measurements immediately following it were replaced with a 0 (as in Thyselius & Nordström 2016).
For details on the processed data ("final_data_activity.csv"), see below.

1b) Name: Raw_data_morphometry_photos
Description: Contains 3 subfolders of photos that were used for the analyses of thorax length, wing length, wing:thorax ratio and coloration.
Subfolders:

• 1_Olympus_SZX10_photographed_dead - These hoverflies were photographed after they died by Olympus SZX10 camera equipped with DF PLAPO 1X -4 JAPAN lens. Individuals could be identified using "First.photo" and "Wing.photo" variables from the "data_morphometry.csv" file. For further information, see more detailed information about "data_morphometry.csv" file below.
• 2_Olympus_E-M10_Mark_II_photographed_alive - These hoverflies were photographed alive by Olympus E-M10 Mark II camera equipped with Olympus ED 12 50 mm f/3,5-6,3 EZ lens. When sorted by name, photos of hoverflies are preceded by photos that state their batch ID and rearing temperature (please note that "RT" stands for 23 °C and "18" stands for 17 °C). Individuals could be distinguished either by their individual marking (blue and white pattern on the thorax), or based on the fact that there are exactly 3 photos of each hoverfly (3 photos taken in a row).
• 3_Olympus_E-M10_Mark_II_photographed_dead - These hoverflies were photographed after they died by Olympus E-M10 Mark II camera equipped with Olympus ED 12 50 mm f/3,5-6,3 EZ lens. When sorted by name, photos of hoverflies are preceded by photos that state their batch ID, rearing temperature and date of death.

2_Processed_data
2a) Name: "final_data_activity.csv"
Description: Activity of hoverflies measured in the Locomotor Activity Monitor LAM25 (TriKinetics Inc, Waltham, MA USA).
Variables:

• Tube = identification number of the glass tube (= position) in the Locomotor Activity Monitor
• Row = identification number of the row of tubes in the Locomotor Activity Monitor
• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Sex = sex of the individual (male/female)
• Batch.ID = identification number of the batch of eggs; each batch was laid by a different female; "weight" stands for hoverflies from a group that was used for regular weight measurements and that has been initially established as a balanced sample of individuals from batches 3, 4, 5 and 7
• Testing.temperature = ideal temperature in the climabox during the experimental session
• Actual.testing.temperature = actual temperature in the climabox during the experimental session measured with an additional thermometer; counted as an average of temperature at the beginning (first day) and at the end (third day) of the experimental session
• Humidity = relative humidity in the climabox during the experimental session
• Date = the second day of the experimental session
• Notes = state of the individual at the end of the experimental session (alright = the individual was alive and well; dead = the individual was dead; ill = the individual had serious locomotory problems and died soon afterwards; one_cotton_fell = the individual was alive, well and was still in the experimental tube, but one of the food-provided cotton balls had fallen down, however, it most likely happened shortly before the end of the experimental session and therefore should not affect the results; got stuck = the individual got stuck with spilled water on the floor of the tube; added later = these individuals were accidentally added to the Locomotor Activity Monitor in the afternoon of the first day, not in the morning, but this should not affect the results as only data between 10:00 and 16:00 of the second day were used for the analysis
• Activity.counts = counts of passing through the center of the glass tube per minute. As hoverflies sometimes stayed in the middle of the tube for prolonged periods of time, resulting in unrealistically high counts, the measurements indicating more than 10 crossing per minute were replaced with a 1 and all non-null measurements immediately following it were replaced with a 0.
• Included.in.the.analysis.1 = dead and ill hoverflies were excluded; due to repeated measurements of several individuals, the dataset was split into two subsets that do not contain more than one measurement per individual; individuals with "yes" value in this column were part of the first dataset
• Included.in.the.analysis.2 = dead and ill hoverflies were excluded; due to repeated measurements of several individuals, the dataset was split into two subsets that do not contain more than one measurement per individual; individuals with "yes" value in this column were part of the second dataset
• Individual.ID = identity code of individual hoverflies

2b) Name: "final_data_pupal_duration.csv"
Description: length of the pupal period, measured as the time from pupation to eclosion
Variables:

• Batch.ID = identification number of the batch of eggs; each batch was laid by a different hoverfly female
• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Pupated = date of pupation
• Eclosed = date of eclosion
• Sex = sex of the individual (male/female)
• Morning.or.afternoon = the part of the day at which the newly eclosed individual was found (0 = morning, 0.5 = afternoon). Note that the "afternoon" hoverflies might have also been eclosed in the late morning/noon.
• Pupal.duration = number of days counted as difference between the day of eclosion and the day of pupation, plus 0.5 for hoverflies that eclosed in the afternoon
• Notes = note that 10 pupae which were reared at 25 °C were moved to the 23 °C for the last 2 days of their pupation

2c) Name: "final_data_eclosion_rate.csv"
Description: Eclosion success rate
Variables:

• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Batch.ID = identification number of the batch of eggs; each batch was laid by a different female
• Eclosed = number of individuals that eclosed successfully
• Not.Eclosed = number of individuals that did not eclose successfully (did not eclose at all or died during crawling out of the pupa)
• Total.pupae = sum of "Eclosed" and "Not.Eclosed" for each category

2d) Name: "final_data_morphometry.csv"
Description: Thorax length, wing length, wing:thorax ratio and coloration
Variables:

• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Batch.ID = identification number of the batch of eggs; each batch was laid by a different female; "weight" stands for hoverflies from a group that was used for regular weight measurements and that has been initially established as a balanced sample from batches 3, 4, 5 and 7
• Sex = sex of the individual (male/female)
• First.photo = name of the first photography portraying the individual hoverfly; usually followed by 1-3 additional photos that follow right afterwards (until another "first photo" occurs in the sequence of files); sometimes the wings were photographed separately, in such cases the name of the photo is in a column called "Wing.photo"
• Wing.length = wing length (mm), measured between the point where transversal h-vein joins the upper edge of the wing and the point where R4+5 vein joins the tip of the wing (as in Ottenheim & Volmer 1999); empty cells indicate that the individual hoverfly lost/wore out its wings before we were able to measure them
• Thorax.length = thorax length (mm), defined as the distance between the scutellum-metathorax border and the head-prothorax border, measured along the center of the metanotum
• Wing.thorax.ratio = Wing.length/Thorax.length; empty cells indicate that the individual hoverfly lost/wore out its wings before we were able to measure them, thus it was impossible to calculate the Wing.thorax.ratio
• Death = status at the moment of taking the photography of the body (died by natural causes/killed by freezing/alive)
• Death.date = day of death; empty cells indicate that the date was not recorded for this particular individual in this dataset
• Death.approx = approximated day of death; empty cells indicate that the date was not recorded for this particular individual in this dataset
• Notes = note that the batch ID of one individual hoverfly was mislabelled in the photography
• Wing.photo = name of photography of a wing of the individual hoverfly; empty cells indicate that the individual hoverfly lost/wore out its wings before we were able to photograph them, or that the photo's unique ID/name was lost (this happened to 6 data points)
• Coloration = coloration on 6 step scale as defined in Heal 1979 (D = dark, MD = medium dark, M = medium, ML = medium light, L = light, UL = ultralight)
• Alive.dead = state at the time of photographing (alive/dead)
• Camera = camera used for photographing the specimen
• Coloration.numeric = the previous coloration scale converted to numbers 1-6 (1 = the lightest, 6 = the darkest)
• Body.photographed = date of taking photography of the body
• Photo.age = age at the time of photographing (in days); empty cells indicate that date of death was missing for the particular individual in this dataset, and thus, we were unable to calculate the Photo.age
• Phenotype = the previous coloration scale converted to a binary scale of either a light phenotype (UL/L/ML), or a dark phenotype (D/MD/M)

2e) Name: "final_data_survival.csv"
Description: Survival in time
Variables:

• Batch.ID = identification number of the batch of eggs; each batch was laid by a different female; "weight" stands for hoverflies from a group that was used for regular weight measurements and that has been initially established as a balanced sample from batches 3, 4, 5 and 7
• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Eclosed = time interval in which the hoverfly has eclosed
• Died = time interval in which the hoverfly has died
• Sex = sex of the individual (male/female)
• Eclosed.approximately = modus of the interval in which the hoverfly has eclosed
• Died.approximately = modus of the interval in which the hoverfly has died
• Status = cause of death of the individual (1 = died by unnatural causes, 2 = died naturally; individuals with status = 1 were included in the survival analysis as censored data)
• Notes = more details on causes of death
• Marking = individual colour marking; empty cells indicate that the individual hoverfly did not have a marking, or that the marking was lost/too worn out to be distinguished
• Lifespan = difference between Eclosed.approximately and Died.approximately; 0.5 was added where the Eclosed.approximately was calculated based on an interval including an even number of days; individuals that died in the pupa or during the eclosion ("unsuccessfully eclosed") are not included in this dataset; an empty cell indicate one individual hoverfly that was seemingly severely damaged during the eclosion, and thus, it has fallen into our definition of the "unsuccessfully hatched" hoverflies, so we did not calculate its lifespan, despite this individual surviving for several days

2*f) Name: "final_data_weight.csv"*
Description: Weight gaining in time
Variables:

• Rearing.temperature = temperature at which the individual experienced the pupation period; from pupation to eclosion
• Eclosed = time interval in which the hoverfly has eclosed
• Pupated = time interval in which the hoverfly has pupated
• Sex = sex of the individual (male/female)
• Weight = weight (g)
• Measurement.number = number of weighting session of the certain temperature group (1 = first weighting session etc.)
• Measurement.date = date of weighting
• Measurement.time = time of the day of weighting
• Notes = notes are mostly refering to individual color markings or state of the wings; in most of the individuals, the wings got very damaged as the hoverflies were aging, so we stopped recording the state of the wings at some point, as most of the hoverflies lost their wings (likely due to being kept in the relatively small insect cages)
• Age.average = average age (in days) at the day of weighting, calculated as the difference between Measurement.date and Eclosed

References

• Ottenheim M., Volmer A. (1999) Wing length plasticity in Eristalis arbustorum (Diptera: Syrphidae). Netherlands Journal of Zoology 49:15-27. doi:10.1163/156854299X00029
• Thyselius, M., & Nordström, K. (2016). Hoverfly locomotor activity is resilient to external influence and intrinsic factors. Journal of Comparative Physiology A, 202(1), 45-54.

Acknowledgement
We thank the Botanic Gardens of Adelaide for their ongoing support, and Lukáš Janošík, Martin Weiser and Zdeněk Janovský for statistical analyses consultations. This research was funded by the US Air Force Office of Scientific Research (AFOSR, FA9550-19-1-0294 and FA9550-15-1-0188), the Australian Research Council (ARC, FT180100289 and DP210100740), Grant Agency of Charles University (464220/2020), the Faculty of Science Foundation of Charles University, and the Mobility Fund of Charles University.