Dataset DOI: 10.5061/dryad.7sqv9s56p

Description of the data and file structure

1. Title of Dataset: Data from: 'Apple floral attractants function across the 24-hour cycle to support potential diurnal and nocturnal pollinators'

2. Dates of data collection: 8 April 2021 – 23 April 2021, 12 April 2022 – 30 April 2022, and 31 March 2026 - 13 April 2026

3. Geographic location of data collection: Milo J. Shult Agricultural Research and Extension Center, University of Arkansas, Fayetteville, Arkansas, United States (36°06′05″ N, 94°10′00″ W)

DATA & FILE OVERVIEW

This dataset contains information on floral volatile composition and nectar volume in apple (Malus domestica) across the diel cycle. It also contains data on insect visits to apple flowers, insect abundance in the same apple orchard where nectar and volatile samples were collected, and environmental conditions during sampling: air temperature, cloud cover, and wind speed. Files 1 and 2 are volatile data. Files 3, 4, 5, 6, and 7 are insect data. File 8 is nectar data.

Nectar was collected during the 2021 field season at five sampling time points, weather permitting: two during the day (11:00 and 16:00), two at night (21:00 and 2:00), and one at dawn (6:00). At each sampling time point, five blooming apple trees were randomly selected, and nectar was collected from five randomly chosen flowers per tree by inserting a 1-microliter Drummond calibrated microcapillary tube into the base of each flower for 1 min.

Flowers for volatile extraction were collected during the 2021 and 2022 field seasons at five time points: two during the day (11:00 and 16:00), two at night (21:00 and 2:00), and one at dawn (6:00). At each sampling time point, two newly opened flowers from the same tree were cut off the stalk and placed in a vial. Three randomly selected trees were sampled per time point, with each sample consisting of two flowers. Flowers from each tree were crushed together and the vial was immediately capped and sealed. Samples were stored at 4 °C. Volatile analysis was conducted on a Shimadzu QP2020 gas chromatograph–mass spectrometer.

Nighttime visitation of apple flowers by insects was documented using three techniques: visual surveys along a transect (moths only), light trap collections, and infrared camera recordings. Transect surveys and light trap collections were conducted in 2021 and 2022. Each transect survey in the orchard lasted 5 min and was carried out at 4 sampling times: 18:00, 22:00, 2:00, and 6:00, during which all moths encountered along the transect were counted. Three pairs of quarter-acre DynaTrap insect traps were installed at different locations within the orchard and collections were conducted in 2021 and 2022 in three time windows: 18:00–22:00, 22:00–02:00, and 02:00–06:00. For infrared video recording, GhostStop full-spectrum night vision cameras were deployed in the orchard during the 2021 and 2026 seasons. Cameras were mounted 1-2 m above ground and aimed at flower clusters containing multiple fresh or newly opened flowers. Cameras operated from 17:45 to 05:45 in 2021 and over the full 24-hour cycle in 2026. Videos were processed with motion-detection software and reviewed manually to count all arthropod visitors to apple flowers.

Air temperature (°C), wind speed (m/s), and cloud cover (fair/cloudy) were recorded at each sampling time point and later verified using hourly weather data for the Drake Field airport (36°00′18″ N, 94°10′12″ W), freely available from the Integrated Surface Database (National Centers for Environmental Information (https://www.ncei.noaa.gov/products/land-based-station/integrated-surface-database). For continuous video recording, we used hourly air temperature (°C), wind speed (m/s), and cloud cover (%) directly from the said weather database. No fieldwork was conducted in the rain.

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2. File List:

File 1 Name: Apple_floral_volatiles_raw_2021.csv

File 1 Description: Comma-delimited file containing raw output from the gas chromatograph-mass spectrometer; 2021 data.

File 2 Name: Apple_floral_volatiles_raw_2022.csv

File 2 Description: Comma-delimited file containing raw output from the gas chromatograph-mass spectrometer; 2022 data.

File 3 Name: Apple_insects_light_traps.csv

File 3 Description: Comma-delimited file containing insect counts in light traps and environmental data.

File 4 Name: Apple_insects_night_camera_cranefly.mov

File 4 Description: Infrared video episode showing a cranefly visiting apple flowers.

File 5 Name: Apple_insects_night_camera_moth.mov

File 5 Description: Infrared video episode showing a hawkmoth visiting apple flowers.

File 6 Name: Apple_insects_transects.csv

File 6 Description: Comma-delimited file containing moth counts in transects and environmental data.

File 7 Name: Apple_insects_video.csv

File 7 Description: Comma-delimited file containing insect counts in infrared camera footage and environmental data

File 8 Name: Apple_nectar.csv

File 8 Description: Comma-delimited file containing nectar volume and environmental data.

DATA-SPECIFIC INFORMATION FOR: Apple_floral_volatiles_raw_2021.csv

1. Number of variables: not applicable (file is a mixture of headers and columnar data)

2. Number of rows: not applicable

3. Variable list: not applicable

4. Missing data codes: blank

5. Abbreviations used:

MC, mass chromatography

Ret.Time, retention time of the peak apex

Proc.From, processing from

Proc.To, processing to

A/H, area/height ratio

Conc., calculated concentration

Ret.Index, retention index

TIC, total ion count

6. Other relevant information: please refer to filenames in the headers for sampling date and time

DATA-SPECIFIC INFORMATION FOR: Apple_floral_volatiles_raw_2022.csv

1. Number of variables: not applicable (file is a mixture of headers and columnar data)

2. Number of rows: not applicable

3. Variable list: not applicable

4. Missing data codes: blank

5. Abbreviations used:

MC, mass chromatography

Ret.Time, retention time of the peak apex

Proc.From, processing from

Proc.To, processing to

A/H, area/height ratio

Conc., calculated concentration

Ret.Index, retention index

TIC, total ion count

6. Other relevant information: please refer to filenames in the headers for sampling date and time

DATA-SPECIFIC INFORMATION FOR: Apple_insects_light_traps.csv

1. Number of variables: 10

2. Number of rows: 43, first row is headings

3. Variable list:

year: 2021 or 2022

date: calendar date (DD-Mon-YY)

endtime: end of a 4-hour sampling window (hh:mm)

temp: air temperature in °C

wind: wind speed in m/s

cloudcover: fair (includes clear sky and scattered clouds) or cloudy (includes partly cloudy and overcast)

totalinsects: total number of insects caught during the 4-hour window of trap operation

moths: number of moths caught during the 4-hour window of trap operation

craneflies: number of craneflies caught during the 4-hour window of trap operation

otherinsects: totalinsects minus moths minus craneflies

4. Missing data codes: not applicable

5. Abbreviations used: not applicable

6. Other relevant information: not applicable

DATA-SPECIFIC INFORMATION FOR: Apple_insects_transects.csv

1. Number of variables: 6

2. Number of rows: 51, first row is headings

3. Variable list:

year: 2021 or 2022

date: calendar date (DD-Mon-YY)

time: time of transect walk (hh:mm)

temperature: air temperature in °C

cloudcover: fair (includes clear sky and scattered clouds) or cloudy (includes partly cloudy and overcast)

wind: wind speed in m/s

moths: total moth count per transect walk

4. Missing data codes: not applicable

5. Abbreviations used: not applicable

6. Other relevant information: not applicable

DATA-SPECIFIC INFORMATION FOR: Apple_insects_video.csv

1. Number of variables: 11

2. Number of rows: 235, first row is headings

3. Variable list:

date: calendar date (DD-Mon-YY)

cluster: flower group ID (character value)

time_bin: 2-hour period of footage (hh:mm:ss-hh:mm:ss)

footage_hr: actual length of usable footage (h)

honeybees: number of honeybees visiting flowers

bumblebees: number of bumblebees visiting flowers

bees_other: number of other bees visiting flowers

wasps: number of wasps visiting flowers

flies_brachy: number of Brachycera flies visiting flowers

flies_nemato: number of Nematocera flies visiting flowers

moths: number of moths visiting flowers

misc: number of other arthropods visiting flowers

temp: air temperature in °C

wind: wind speed in m/s

cloud_pct: cloud cover expressed as percentage

4. Missing data codes: not applicable

5. Abbreviations used: not applicable

6. Other relevant information: not applicable

DATA-SPECIFIC INFORMATION FOR: Apple_nectar.csv

1. Number of variables: 8

2. Number of rows: 780, first row is headings

3. Variable list:

date: calendar date (DD-Mon-YY)

time: time of sampling (hh:mm)

tree: individual tree (1 through 156)

sample: individual flower sampled (A through E, unique to tree)

nectar: nectar volume per flower, in microliters

temperature: air temperature in °C

cloudcover: fair (includes clear sky and scattered clouds) or cloudy (includes partly cloudy and overcast)

wind: wind speed in m/s

4. Missing data codes: not applicable

5. Abbreviations used: not applicable

6. Other relevant information: not applicable

Access information

Data was derived from the following sources:

• Weather data for video recordings were imported from the Integrated Surface Database (National Centers for Environmental Information (https://www.ncei.noaa.gov/products/land-based-station/integrated-surface-database).