Table 1
Hypotheses on reasons behind washboarding behaviour, based on scientific reports in the literature
| Available hypotheses explaining washboarding, found in the literature at the end of the 19th-beginning of the 20th century, as cited in Alfonsus (1932) | ||
| Mentioned Author(s) | Year of report | Explanation for washboarding |
| Dönhoff | 1860 | playing instinct |
| Schmid & Kleine | 1861 | playing instinct |
| Mehring | 1866 | wax lining |
| Kleine | 1866 | scraping to remove fungi and lichens |
| Buttel-Reepen | 1915 | playing instinct |
| Haidak | 1929 | scraping |
| Vahan | 1930 | petting something |
| Betts | 1931 | propelling the content of the honey-sac and exuding other substances |
| Alfonsus | 1932 | mechanical cleaning |
| Available hypotheses explaining washboarding, found in the literature 21st - 22nd century, as cited in Taulmann (2017) | ||
| Author(s) | Year of report | Explanation for washboarding |
| Gary | 1992 | cleaning the surface around the hive entrance, removing any loose particles, parasites, fungi, or other debris |
| Bohrer and Pettis | 2006 | |
| Garvey | 2012 | keeping active during scarcity of food sources |
| Taulmann | 2017 | applying an attractive scent to the surface around the entrance, to help foragers to orientate |
Fig. 1
Observations and experiments on hives: a) visual inspection of hive surfaces; b–c) lichen transplants composed of bark stripes glued on satin ribbons. b) D-type sample, collected in Portugal in 2018 and c) A-type sample, collected in Italy in 2019; d) placement of transplants. Photo record: Davide Romani.
Fig. 2
Beekeepers responding to a questionnaire indicate the frequency of their observations of washboarding. On the right, details on the number of times that each respondent observed the washboarding behaviour.
Fig. 3
Relative importance of possible explanations of washboarding, expressed as posts related to YouTube videos. They are grouped based on main themes.
Fig. 4
Bee responses to lichen stripes transplant: a) washboarding behaviour; b) lichen stripe sample conditions before placing; c) same sample as in b), after two months of exposure in front of the hive: evidence of lichen removal; d–f) decoloration of those lichens present on the bark slice after two months of exposure.
Table 2
List of identified lichen species present on each bark stripe used during the field experiment
| Lichens present (x) on bark stripes collected in Italy in May 2019 | ||||||||||
| A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8 | A9 | A10 | |
| Amandinea punctata | x | x | x | x | ||||||
| Caloplaca cerina | x | |||||||||
| Candelaria concolor | x | x | x | x | x | x | x | x | x | x |
| Hyperphyscia adglutinata | x | x | x | x | x | x | x | x | x | x |
| Lecania cyrtella | x | x | x | |||||||
| Lecidella elaeochroma | x | x | x | |||||||
| Phaeophyscia orbicularis | x | x | x | x | x | x | ||||
| Physcia adscendens | x | x | x | x | x | x | x | x | ||
| Physcia aipolia | x | |||||||||
| Physcia dubia | x | |||||||||
| Scoliciosporum sp. | x | |||||||||
| Xanthoria parietina | x | x | x | x | x | x | x | x | x | x |
| Lichens present (x) on bark stripes collected in Portugal in April 2018 | ||||||||||
| D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8 | D9 | D10 | |
| Arthonia radiata | x | |||||||||
| Hyperphyscia adglutinata | x | x | x | x | x | |||||
| Lecanora chlarotera | x | x | ||||||||
| Lecidella elaeochroma | x | |||||||||
| Pertusaria sp. | x | x | ||||||||
| Physcia erumpens | x | x | x | |||||||
| Xanthoria parietina | x | x | x | x | x | x | x | x | ||
Table S1
Website list
| Website | Brief summary of content | Opinion/info | |
|---|---|---|---|
| 1 | https://beekeep.info/a-treatise-on-modern-honey-bee-management/the-basis-for-management/mysterious-behaviors-of-honey-bees/washboard-behavior/ Last accessed: 18 Jan. 2021 | Site dedicated to informing beekeepers managed by The Apis Information Resource Center, developed by Dr. Malcolm T. Sanford, Professor Emeritus, University of Florida | intriguing behaviour; presentation of results of Bohrer, K., & Pettis, J.S.; hosting 2 videos and a link too a google page listing results for washboarding behaviour |
| 2 | https://honeybeesuite.com/washboarding-bees-arockin-and-alickin/ Last accessed: 18 Jan. 2021 | Site dedicated to informing beekeepers and people managed by Sam Droege, USGS Patuxent Wildlife Research Center | Brief description in the blog, reporting results of Bohrer, K., & PettisJ.S.; hosting 1 video 22 replying posts |
| 3 | https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=7586 Last accessed: 18 Jan. 2021 | Informative site of the Agriculture and Natural Resources, University of California Blog-Article by Kathy Keatley Garvey. | It would be interesting to find out; 14 replying posts |
| 4 | https://beekeepingforum.co.uk/showthread.php?t=33125 Lastaccessed: 18 Jan. 2021 | UK Beekeeping Forum. Various posts. | reporting info of Bohrer, K., & Pettis, J.S.; 10 replying posts |
| 5 | https://www.beesource.com/forums/showthread.php?230659-Washboarding Lastaccessed: 18 Jan. 2021 | Forum community dedicated to beekeeping, bee owners and enthusiasts. 6 discussions following a starter post. | reporting info of Bohrer, K., & Pettis, J.S.; 70 replying posts |
| 6 | http://iussi.confex.com/iussi/2006/techprogram/P2650.HTM Lastaccessed: 18 Jan. 2021 | From the program of an International Conference (IUSSI 2006). Poster presentation related to washboarding behaviour by Bohrer, K., & Pettis, J.S. | The function of this behaviour remains to be elucidated, after experimental observations of worker age and surface texture. |
| 7 | http://www.myrmecos.net/2010/08/19/washboarding-bees/ Lastaccessed: 18 Jan. 2021 | Informative website by Alex Wild. Posted video. | Description, no hypotheses; 13 replying posts |
| 8 | https://forum.honeyflow.com/t/theories-on-washboarding/9718 Lastaccessed: 18 Jan. 2021 | Informative website by a private company. Posts following introduction of topic: Theories on Washboarding | Description, + hypotheses; 20 replying posts 1 video |
| 9 | http://www.keltronixinc.com/washboarding-bees/ Lastaccessed: 18 Jan. 2021 | Informative website by a private company. Posts following introduction of topic: Washboarding Bees | Description, + videos, + hypotheses; |
| 10 | http://www.beeculture.com/ask-phil-november-2014/ Lastaccessed: 18 Jan. 2021 | Bee Culture The Magazine of American Beekeeping. Article/post by Phil Craft, November 1, 2014 | Responding to post |
| 11 | https://forum.canberrabees.com/t/bees-washboarding/200/2 Lastaccessed: 18 Jan. 2021 | Site dedicated to informing beekeepers Posts following introduction of topic: Bees washboarding | Description, + videos; 2 replying posts |
Table S2
YouTube video listNeoSansIntel-Medium
| Link to Videos | Title /Author /date of post | Visualizations /comments | |
|---|---|---|---|
| 1 | https://www.youtube.com/watch?v=lbwumXVTOz8 | Bees Washboarding AlexWild73 20 Aug. 2010 | 45.313 / 24 |
| 2 | https://www.youtube.com/watch?v=sxjc4tSKJFs&feature=emb_logo | Washboard Behavior Dr. James E. Tew 30 Aug. 2012 | 28.338 / 69 |
| 3 | https://www.youtube.com/watch?v=tcJtJdke0AQ | Washboarding/Bees Don The Fat Bee Man 31 Aug. 2012 | 19.419 / 10 |
| 4 | https://www.youtube.com/watch?v=0qncNbsh4_0&t=118s | Washboard Movement of Honey Bees (Example and Explanation) Honey Bee Honey 13 Nov. 2015 | 12.023 / 8 |
| 5 | https://www.youtube.com/watch?reload=9&v=h6oaASApNk4&feature=emb_logo | HONEY BEE Apis mellifera washboarding mystery solved? Dr. Tom Seeley is right. insidethehive.tv 18 Aug. 2019 | 9.871 / 37 |
| 6 | https://www.youtube.com/watch?v=yUDBk9VTypc&t=149s | When Honey Bees Do The Washboarding Thing David Burns 4 Aug. 2016 | 8756 / 20 |
| 7 | https://www.youtube.com/watch?v=DBZpa-6rs8A | Nectar Dearth, Wash Boarding Bees And Never Getting Poison Ivy Again Jason Chrisman 16 Aug. 2020 | 7.644 / 98 |
| Link to Videos correlating washboarding to propolis distribution | Title / Author /date of post | Visualizations /comments | |
| 8 | https://www.youtube.com/watch?v=tXWefJhw2rA&feature=youtu.be | Honeybee Propolis and Washboarding is there a connection? 18 bees 24 Aug. 2020 | 3.872 / 46 |
| 9 | https://www.youtube.com/watch?v=y3gUqC694D4 | Does bee washboarding on boxed hives mimic propolising in nature? 18 bees 10 Sept. 2020 | 2.774 / 27 |
| 10 | https://www.youtube.com/watch?v=6NRjYNJEb6g | Bees Washboarding Jossamer Jedi 22 Nov. 2015 | 126 / 0 |
| Link to other interesting Videos | Title / Author /date of post | Visualizations /comments | |
| 11 | https://www.youtube.com/watch?v=EavTZt8ybDc | Wash boarding bees Justified Bee 7 May 2017 | 0/0 |
| 12 | https://www.youtube.com/watch?v=1t8JyQTUmSs | Bees shimmering or washboarding John Haverson 17 Aug. 2016 | 282/0 |
| 13 | https://www.youtube.com/watch?v=2WIeAd_ATko | Bee tree bees wash boarding today Hooterville Honey bees 22 Aug. 2020 | 22/1 |
| 14 | https://www.youtube.com/watch?v=K6LJyVnqFYU&fbclid=IwAR2FsbjtCHHzZi16cOaXWijeQUnuWdhKhCuJOKRCQDqIsIZqZvc8tKs6JOY | Honeybees foraging on lichen? Very interesting honeybee behavior Swarmstead Bees & Gardening 22 Oct. 2020 | 362/13 |
Table S3
Fv/Fm values (±SD; n=3) in X. parietina after exposure
| Sample | Fv/Fm | Observations |
|---|---|---|
| D1 | 0.22±0.20 | depigmentation, presence of propolis on the surface |
| D2 | NA | absent |
| D3 | 0.22±0.39 | depigmentation, presence of propolis on the surface |
| D4 | 0.16±0.17 | depigmentation |
| D5 | 0.15±0.15 | depigmentation |
| D6 | 0 | depigmentation |
| D7 | 0.21±0.19 | presence of propolis on the surface |
| D8 | 0.42±0.13 | depigmentation |
| D9 | 0.42±0.37 | depigmentation, presence of propolis on the surface |
| D10 | 0.15±0.13 | depigmentation |
| A1 | 0.27±0.25 | presence of propolis on the surface |
| A2 | 0.28±0.08 | presence of propolis on the surface |
| A3 | 0.06±0.03 | depigmentation |
| A4 | 0.16±0.13 | presence of propolis on the surface |
| A5 | 0.39±0.06 | presence of propolis on the surface |
| A6 | 0.41±0.05 | no changes observed |
| A7 | 0.15±0.12 | depigmentation |
| A8 | 0.32±0.29 | depigmentation |
| A9 | 0.41±0.08 | no changes observed |
| A10 | NA | absent |
Fig. S1
Study area, where apiaries under experimental manipulation were placed, 45°13′59.96″N; 11°27′56.8″E, north-east of Italy.
Maps credits: northern Italy at https://d-maps.com/carte.php?num_car=5880&lang=it;detail of the study area at https://www.google.it/maps (Immagini ©2022, TerraMetrics, Dati cartografici ©2022 Google)