A blog post highlighting the article that received the prize for the best paper published in Insectes Sociaux in 2018 by Paul J. Davison and Jeremy Field.

By Paul Davison and Jeremy Field

 

Paul’s Ph.D. focussed on the unusually varied social biology of sweat bees, which include eusocial species, solitary species and also socially polymorphic species. In socially polymorphic sweat bees, some populations have eusocial nests with a queen and workers, while in other populations of the same species all nests are solitary. Solitary populations are always found at cooler latitudes and/or higher altitudes than eusocial populations. Likewise, obligate eusocial species, in which nests always have queens and workers, never occur at the coolest latitudes or higher altitudes alongside solitary species or populations. The main element of the Ph.D. involved performing a field transplant to explore how the environment influences behaviour in a socially polymorphic sweat bee (for the results, see Davison & Field (2018) Behavioral Ecology & Sociobiology 72:56).

 

 

We thus became interested in what limits the geographic distribution of eusociality in sweat bees. It has long been thought that once the growing season becomes too short, it is no longer possible to sequentially produce the successive worker and reproductive broods necessary for eusociality and the only option is solitary nesting. Noticing that this had not been tested experimentally, we thought it would be interesting to do just that. The best way would be to conduct another transplant, only this time of an obligate eusocial sweat bee far to the north of its natural range.

 

 

We chose to transplant Lasioglossum malachurum, a well-studied obligate eusocial sweat bee that is restricted to the south and east of Britain. We wanted to investigate the reasons for this, and in particular whether it is related to the length of the season. Because of other fieldwork commitments, this project would have to be ‘smash and grab’, or ‘smash and transplant’. Jeremy had the ingenious idea of getting spring foundresses to nest inside plastic buckets and then transplanting them and their nests wholesale. To do this, we spent winter digging trenches adjacent to where the bees nested in southern England, filling buckets with the excavated soil then putting them back into the trench and filling in the gaps. In essence, digging holes and filling them in again! By transplanting buckets after nests had been initiated in spring but crucially before foundresses began provisioning, we could test how being in a northern environment with a shorter season would impact the eusocial lifecycle.

 

 

We were generously allowed to embed our transplanted buckets in the garden of the University of Aberdeen’s Lighthouse Field Station at Cromarty in northern Scotland. Cromarty is much further north than where L. malachurum occurs naturally and is a place most people have only heard of thanks to the BBC Radio 4 shipping forecast. Nestled between the 1840s lighthouse and stunning Cromarty Firth, the bees would certainly have a good view if nothing else. Equally generously, since it involves hours of scraping away at a block of soil on a table and is incredibly messy, Paul was able to excavate the buckets in rooms owned by the Cromarty Arts Trust. We transplanted control buckets to the University of Sussex campus, well within the bee’s natural range. All that remained was to see whether driving the length of Great Britain with buckets of nesting sweat bees would pay off.

 

 

The results were unequivocal. When we excavated the nests eight weeks after transplanting them, first brood offspring at Sussex were all nearing the completion of development, whereas in Scotland most offspring were still tiny larvae that had not long hatched. We estimated that this represented a lag of approximately seven weeks behind Sussex and that, had they been left to complete development, the first brood in Scotland would not have emerged as adults until August! This would leave no time for workers to provision a reproductive brood successfully. We found that the time lag corresponded to differences in temperature, which is well known to influence the timing of bee activity and seems to have caused foundresses in Scotland to begin provisioning much later in the spring. Importantly, this reflects environmental constraints on provisioning behaviour rather than the strategic shift between social and solitary nesting seen in some socially polymorphic sweat bees (Field et al. (2010) Current Biology 20:2028-31).

 

 

All in all, some intriguing results. Jeremy is planning to take this initial work further with more replicates and a detailed study of what exactly causes the time lag.

Highlighting upcoming research from Thomas Parmentier entitled ‘Host following of an ant associate during nest relocation’, to be published shortly in Insectes Sociaux

Even more fascinating than ants, is the extremely diverse group of arthropods that live strictly in their nests. Gradually, we learn that these creatures, commonly  referred to as myrmecophiles or ‘ant loving’, possess an array of chemical, morphological and behavioural adaptations to by-pass ant aggression and to make a living in the hostile nest environment (Kronauer and Pierce 2011). Many myrmecophiles are parasites that feast on a lavish banquet of brood and other resources found in the nest (Parmentier et al. 2016a).

What is rather unknown so far, is how myrmecophiles move in the landscape and target new nests. It can be expected that myrmecophiles are prompted to colonize new nests, when nest conditions start to deteriorate or when competition with other myrmecophiles becomes too strong. During my current postdoc project, I study the spatial dynamics of myrmecophiles associated with European red wood ants. These ants are famous for their large mound nests and aggression, yet their nests harbour a rich community of myrmecophiles (Parmentier et al. 2014).

Last spring, I visited a study site in the north of Belgium and to find out whether the wood ant colonies (Formica polyctena) made it through the winter and whether new nests were founded. Then, I observed that one colony was moving to a new nest site a couple of metres away. As I have been curious for a long time how myrmecophiles would respond to the desertion of their home, I carefully inspected the horde of moving workers. To my surprise, I saw that a group of larvae of the beetle Clytra quadripunctata (Chrysomelidae) were crawling among the moving colony towards the new nest site. A bit later, some larvae were also dragged by the workers to the new nest. Luckily, these days, smartphones are equipped with rather decent cameras, so I was able to record this rare event. There are some old and anecdotal notes which suggest that some myrmecophiles are also able to track their host during relocations to a new permanent nest site, but this has not been recorded so far.

The biology of Clytra quadripunctata is rather peculiar. The adults are adorable beetles that feed on plants near the nest. After mating, the female drops her eggs. The larvae enter the nest and remain there probably for 2 years (Donisthorpe 1902). Lab tests demonstrated that the larvae are brood predators and scavengers. They preferentially reside in the heated brood chambers in the centre of the nest (Parmentier et al. 2016b). The larvae of this beetle are protected by a pear-shaped case in which they can retract. After pupation, the adults sneak out of the ant nest.

My observations suggest that the beetle larvae adaptively respond to rare nest-moving events. Interestingly, they can find the new nest site on their own or be carried by workers unaware of the danger that is hiding in the case. Nonetheless, a significant fraction of the larvae did not find the new nest and remained in the abandoned nest. Wood ants are thought to move occasionally when microclimatic conditions become suboptimal. However, they may also be triggered to relocate to a new nest site in order to reduce parasite load. This could end up in an evolutionary arms race where the host will move more frequently and more distantly, whereas the parasite will develop more advanced strategies to follow or locate its host. This is a tempting hypothesis that deserves further research.

This observation has galvanized me to unravel some more secrets of myrmecophile dispersal the coming years. More information on the progress of my research on myrmecophiles can be found at:

https://www.researchgate.net/profile/Thomas_Parmentier

 

Donisthorpe HSJK (1902) II. The Life History of Clythra quadripunctata, L. Trans R Entomol Soc London 50:11–24.

Kronauer DJC, Pierce NE (2011) Myrmecophiles. Curr Biol 21:208–209.

Parmentier T, Dekoninck W, Wenseleers T (2014) A highly diverse microcosm in a hostile world: a review on the associates of red wood ants (Formica rufa group). Insectes Soc 61:229–237.

Parmentier T, Bouillon S, Dekoninck W, Wenseleers T (2016a) Trophic interactions in an ant nest microcosm: a combined experimental and stable isotope (δ13C/δ15N) approach. Oikos 125:1182–1192

Parmentier T, Dekoninck W, Wenseleers T (2016b) Do well-integrated species of an inquiline community have a lower brood predation tendency? A test using red wood ant myrmecophiles. BMC Evol Biol 16:12.

 

Hello, social insect community!

2018 was productive for the social insect community, especially for Insectes Sociaux. As the new Social Media Editors, we have been enjoying collaborating with many social insect scientists on blog posts. Thank you for your contributions not only to making our journal great but also our blog, whether that’s through reading or writing! As 2018 came to an end and we were reflecting on the year, we reached out to past blog contributors to see what they’ve been up to. Here are some 2018 highlights from social insect scientists:

Kaitlin Baudier, Postdoctoral Research Associate, School of Life Sciences, Arizona State University

You can find Dr. Baudier at kmbaudier.weebly.com and @AntGirl_KB. She also has a YouTube channel.

IS: What is the most exciting thing you’ve learned about your study species in 2018?

KB: On the army ant front (pun intended) I learned a lot about bivouacs in 2018. It turns out that bivouacs of the most well-studied army ant (Eciton burchellii) do not strictly thermoregulate as was previously thought. At high elevations, we found that bivouacs selected different thermoregulatory strategies dependent on brood developmental stage. When ambient temperatures were low and bivouacs were filled with predominantly larvae, bivouacs would allow energy-conserving cooling. However, bivouacs rich in pupae were always kept warm regardless of ambient temperature. We report on this energy-saving strategy for coping with high elevation cold temperatures in our recent paper in Ecography. This was an interesting turn in our bivouac elevation project which we first published in Insectes Sociaux back in 2016.

2018 also marked my first work on the topic of nest defense in the stingless bee Tetragonisca angustula. This species is famous for having two types of nest entrance guards: hovering and standing guards. In our paper currently in revision at Behavioral Ecology, we report that task allocation between these two guarding jobs is age-dependent, with younger bees hovering guarding and older bees standing guarding. This was an unexpected and exciting finding in our study which had initially set out to collect task allocation data for a bio-inspired design project aimed at improving defensive swarm algorithms in unmanned aerial vehicles (Strickland et al. In Press). We also found that roaming Ectatomma tuberculatum ants use sit-and-wait predation to make a meal of these guard bees. Life for a guard bee can be rough.

IS: What was your favorite conference and/or fieldwork experience?

KT: IUSSI 2018 in Brazil really blew the top off of my idea of what a great conference could be. Not only did I get a chance to speak with a multitude of established social insect biologists from around the world, but it was an excellent opportunity for me to meet a lot of amazingly dedicated students and to learn about their respective projects. I walked away from Brazil 2018 with more than a few new collaborators. As for fieldwork, I have been having an extremely positive experience working with the Smithsonian Tropical Research Institute in Panama this past year. From my fieldwork in and around BCI and Gamboa to my returning to co-instruct the ASU Tropical Biology course at STRI in the summer, I have enjoyed getting to know the insects, the people, and the environment in Panama. As 2019 begins, I am already packing my field equipment for another trip back. Some days I can’t help but think that it doesn’t get any better than this.

 

Rachael Bonoan, Post-Doctoral Researcher, Tufts University and Washington State University

You can find Dr. Bonoan at www.rachaelebonoan.com and @RachaelEBee.

IS: What is the most exciting thing you’ve learned about your study species this year?

RB: This year, I started a post-doc studying the natural history of an ant-caterpillar relationship in a Pacific Northwest prairie. When it’s a caterpillar, the Puget blue butterfly, is protected by ants. In return for protection, the caterpillar secretes a sugary snack for the ants. As mentioned in my Interview with a social insect scientist, part of my job is to figure out which ants live on the prairie with my Puget blue caterpillars.

With the help of two Tufts University undergraduates, Hanna Brush and Max McCarthy, we have identified ten species of ants on our field site! (Many thanks also go out to Stefan Cover at the Harvard Museum of Comparative Zoology and Chad Tillberg at Linfield College for help identifying and pinning specimens.)

So far, there are two dominant ant species on our prairie: Formica obscuripes (the Western thatch ant) and Tapinoma sessile (the odorous house ant). We have seen both tending Puget blue caterpillars, this bodes well for the baby butterflies!

The most exciting species we identified, however, is Ployergus mexicanus, also known as the raider ant or the pirate ant. The raider ant has sickle-shaped mandibles (mouthparts) specialized for kidnapping young from other ant colonies. The ultimate moocher, this ant species cannot feed itself or take care of its own young.

After mating, a female raider ant infiltrates the colony of another ant species, typically a Formica species. The female raider ant subdues Formica workers with a specialized pheromone and promptly overtakes their queen. With the Formica queen out of the way, the raider ant queen is ready to begin her reign—she lays eggs that the Formica workers raise. With the help of their sickle-shaped mandibles, raider ant workers spend their days raiding other Formica colonies and kidnapping their young. This ensures that there will always be enough Formica workers to raise more raider ant workers.

IS: What was your favorite conference and/or fieldwork experience?

RB: This year, I attended two great conferences: Entomology in Vancouver, B.C. and Social Insects in the North East Regions (SINNERS) in Philadelphia, PA. While I enjoyed both conferences, SINNERS was held at the coolest conference venue: the Natural Academy of Sciences of Drexel University (a museum!). During the meeting, the museum had a fantastic exhibit: Xtreme Bugs! This exhibit celebrated “extreme insects” with giant, animatronic models of the amazing beats. My favorites were, of course, the leafcutter ants and the honey bee!

Excellent venue aside, SINNERS is one of my favorite conferences. This relatively small conference (~50 speakers this year) gives you the opportunity to get to know social insect scientists! Since it’s a regional conference, SINNERS also a great meeting to find nearby social insect friends and collaborators. I met James Waters at SINNERS 2015, and we have continued to stay in touch! James and his students have visited my honey bees at Tufts (they even lent us a wireless temperature sensor for my research), and I have given a couple guest lectures in James’s classes at Providence College!

 

Tomer Czaczkes, ACElab Group Leader, University of Regensburg

You can find Dr. Czaczkes at animal-economics.com and @tomerczaczkes.

IS: What is the most exciting thing you’ve learned about your study species this year?

TC: We started trying to train Drosophila to associate odours with food qualities. Man, those things are thick as glue! It gave me a real appreciation for our study species, Lasius niger – we found that these ants can learn an odour / food quality association reliably after just one exposure. I admit that perhaps the flies could learn that quickly if one used precisely the right method. Perhaps. So maybe rather than being thick, they are fiddly and delicate. Really makes me appreciate how robust and easy to work with our ants are.

 

The Insectes Sociaux editors have also been curious about our social media followers. To learn more about the kinds of scientists in our Twitter community, we recently put out a series of polls. Overall, we’ve learned that most of our followers study behavior and bees, and wish they had more time for fieldwork. Here are the results!

 

“We know all social insects are great, but what is your favorite?”

41% Bees

40% Ants

12% Wasps

7% Termites

 

“What do you predominantly study?”

51% Behavior

18% Ecology

6% Morphology

25% Combination of all of the above

 

“What component of your work do you wish you had more time for?”

49% Fieldwork

35% Publishing/writing

8% Teaching

8% Outreach / science communication

 

What have you been up to recently with your science? Do you have a comment or suggestion for our blog, social media presence, or journal? We would love to hear from you! Follow us and send us a message through Facebook, Instagram, or Twitter.

Happy new year! We hope you have fulfilling scientific endeavors in 2019.

Madison Sankovitz & Bernie Wittwer, Social Media Editors, Insectes Sociaux

 

A blog post highlighting the article by S. Łopuch & A. Tofilski in Insectes Sociaux

By Sylwia Łopuch and Adam Tofilski

 

The behavior of honey bees (Apis mellifera) still contains a plethora of mysteries. After many decades of research, bee communication is still not entirely understood. Efficient communication is particularly important for social insects such as honey bees because a single colony consists of tens of thousands of bees that need to cooperate to survive.

A high-speed camera may be beneficial to the study of social insect communication because it can record thousands of frames per second. As a result, high-speed video recording lets us see details that are undetectable to a human eye.

Observations of a few colonies of honey bees with the use of a high-speed camera revealed that the bees moved their wings in temporal and behavioral patterns within the nest. We housed colonies in observation hives (which consisted of two frames with bees placed behind glass walls) and recorded the bees’ behavior. The wings remained motionless most of the time. However, occasionally bees with folded wings performed a few wing beats. Interestingly, this behavior was observed not only in workers but also in queens and drones. The wing movements were detected most often during the swarming season (the reproduction period for honey bees). The queens performed this wing behavior only at that time. Similarly, drones vibrated their wings only during preparation for mating flights and when they were evicted from the nest by workers. The wing movements were observed most often in workers, which moved them both during the swarming season and outside of it (video). Workers moved their wings when they were in contact with a queen or another worker, including workers returning to the nest with food (pollen or nectar) and those guarding the nest entrance.

Our observation that the honey bees moved their wings when they were in contact with other bees led us to assume that the function of the wing movements is related to communication. We also recorded wing movements of dancing bees. Workers perform the waggle dance when they find an attractive source of food. After they return to the nest after foraging, they dance to transfer information to other nestmates about the location of the food source. It is possible that frequency of wing beats (the number of wing beats per second) and duration of episodes of wing beating transfer some information because these metrics significantly differed in queens, drones, and workers. The characteristics of the wing movements also depended on temporal context, differing in the swarming and non-swarming seasons. Therefore, wing movements may support communication based on vibrations in the darkness of nests where visual cues are ineffective.

In conclusion, high-speed video recording allows us to observe unknown behaviors of honey bees like wing movements and help us better understand their meaning.