Highlighting the article written by Middleton, Reid et al. in Insectes Sociaux

Written by Insectes Sociaux Editor-in-Chief, Michael Breed

What happens when an animal has choices of navigational information from two or more sources? In foraging social insects, this choice often occurs when workers have the decision to use either learned navigational cues and pheromone trails or markers. Using learned cues may involve trade-offs between speed and accuracy, as movements oriented to landmarks are usually faster than movements based on continuous search for pheromone cues, but the workers may be less prone to errors when following pheromone trail.

An added wrinkle to this trade-off is that the accuracy of landmark based navigation usually improves with experience. An animal that has navigated a route several times may move more confidently, accurately, and rapidly than a naïve individual. This experiential shift can also represent a gradual shift from the use of social cues, such as pheromones, to internalized landmark memory (which can be considered private information), with some reliance on both types of cues during intermediate stages.

In this issue, Middleton, Reid, and their colleagues investigate these shifts in information usage in Australian meat ants, Iridomyrmex purpureus, using a y-maze experimental design (Middleton, Reid et al 2018). They found that, as with other species of ant, experienced workers use landmark information in preference to trail pheromone information, and that if the trail information is removed, experienced workers continue to be able to navigate the route. The memorized route information is considered private (internal to the individual) while the pheromone information is public (available to all colony members).

A unique element of this study is the discovery that the meat ant workers’ performance using private information does not improve with repeated experience; they do well with private information after just navigating the route once. Regarding learning style, this rapid acquisition of information matches well with imprinting, in which an animal rapidly acquires critical information. This pattern differs from the learning curve, showing improvement over trials, that typically results from trial and error learning. This finding supports the critical role of navigational accuracy in successful social insect worker foraging. It would be fascinating in future studies to further explore the speed with which navigational route is acquired by ants and to compare those results with the much more thoroughly studied honey bee.

Because foraging by social insects is usually a cooperative, rather than a competitive, venture for workers from the same colony, the concept of private versus public information applies differently than in other behavioral contexts. In systems involving competition, including attraction of mates or food search by non-cooperating animals, information is held privately because it has particular value to the holder, and that value would be compromised if other animals, by eavesdropping or spying, capture the information.

The use of the public/private categorization in this context, though, is intriguing because it raises the question of at what point would a forager become motivated to share its private information publicly, by re-laying pheromone trail or communicating an alternative more direct route to the goal? This question leads to additional possible future directions, with studies focused on the mechanisms of choice between continuing to forage and shifting to providing social information to colony-mates.

References

Middleton EJT, Reid CR, Mann RP, Latty T (2018) Social and private information influence the decision making of Australian meat ants (Iridomyrmex purpureus). Insect Soc
doi.org/10.1007/s00040-018-0656-1

IS: Who are you and what do you do?

I am an instructor at the University of Alberta Augustana. I did my BSc and MSc at the University of Alberta, Canada, and recently graduated with my Ph.D. from the University of New South Wales, Australia. Most of my research has focused on ant ecology and other myrmecological topics. A lot of my research has focused on ant diversity and ecology in western Canada. However, I also developed an interest in the global patterns of myrmecophiles (organisms that closely associate with ants) during my Ph.D. studies.

 

 

IS: How did you develop an interest in your research?

Well, I have been interested in ants ever since I was a kid playing in the garden; I would sit in the grass and just watch them do what ants do. I also like the thrill of discovery, and at one point in my life I wanted to be a palaeontologist because I loved finding fossils and discovering something that no one had ever seen before. Science, however, is often about discovery and that feeling of wonder can be found in any scientific topic. During my undergraduate degree, I did an independent project in entomology, specifically looking at ants from Alberta. This project captivated me, as it seemed like every time I looked under the microscope I was finding a new ant record for the area. Finding out that we knew so little about ants in western Canada led me to switch from palaeontology to entomology and I have been studying ants ever since!

 

 

IS: What is your favourite social insect and why?

That is a difficult question, as there are so many fascinating social insects. I would have to say Formicoxenus ants are some of my favourites. They are social parasites of larger ants, such as Formica or Myrmica, and live within their host ant colony. These much smaller ants use their hosts for protection, but also steal food from them by running up and begging to be fed. Moreover, the male ants of these species have evolved to be more worker-like, often are wingless, and may actually help in colony activities! These unique ant traits make Formicoxenus a fascinating genus of social insects.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

Probably discovering that there are a lot more ants in Alberta than was previously thought. When I started my work, there was believed to be about 50 ant species; now that estimate is closer to 100, not including introduced species. For some ants, their known range was extended by over 1500 km. For me, it was fantastic and memorable to expand our knowledge of where these ants can be found, and it is always fun to have that rush of discovery when you find a new ant you haven’t seen before.

IS: Do you teach or do outreach/science communication? How do you incorporate your research into these areas?

At the moment, I am teaching environmental sciences at the University of Alberta Augustana Campus. I work my research into the conservation parts of the course and try and engage students by exhibiting how there is still so much we can discover about the world around us.

In the past, I have done presentations with nature clubs to help spread knowledge about ants. A lot of people see ants as just annoyances in their garden or lawns, so teaching them that they are diverse, socially complex, and ecologically interesting is essential to helping them see ants as part of a wider world.

IS: What do you think are some of the important current questions in social insect research and what’s essential for future research?

I think understanding the simple ecology and biology of social insects is still incredibly important. What are these insects feeding on? What are their effects on the ecosystem? What relationships do they have with other species? How do changes in the environment affect them? If we take the time to fully understand individual species, we can better understand their influence on the world and how the world influences them. This basic biological understanding becomes even more critical when considering the conservation of biodiversity and trying to prevent human-driven extinctions, as it gives necessary information to work from.

IS: What is the last book you read? Would you recommend it? Why or why not?

Tanya Huff’s Confederation novels. I would recommend them for science fiction readers, as they are a fun take on the “space marine” genre. It is a fun adventure series with good dialogue, exotic aliens, and an imaginative world.

IS: Outside of science, what are your favourite activities, hobbies or sports?

I enjoy birding, especially in the winter when the ants are covered in snow. In Alberta, winter is when owls, such as Snowy or Great Greys can be found more easily, so it is a fun pastime in a land of white! I also play a lot of soccer and have been playing on the same team, with the same group of guys, since I was a teenager. Additionally, I enjoy having aquariums and terrariums, and at the moment have Imitator Dart Frogs (Ranitomeya imitator). Sadly, my ant-keeping skills could use some work.

IS: How do you keep going when things get tough?

Life is full of challenges; some can be fun, and some can be difficult. If I am in a particularly tough spot, I often take a break, reassess how to fix the issue, and then try to fix it. I have also been known to rant about the problem to my wife, who lovingly listens and helps me solve it. If things are really tough, it is always nice to get out and just watch nature, be it ants, birds, or other animals.

IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

1. Gear to collect ants because there could be an interesting species! 2. A lot of clean, fresh water so that I don’t dehydrate. 3. A satellite phone so that when I am out of food/water and have found all the ants, I could call someone to come pick me up.

IS: Who do you think has had the most considerable influence on your science career?

John Acorn. He is a professor at the University of Alberta. He was my master’s supervisor and is a great friend. He taught me to think critically, write succinctly, and how to observe the living world. His guidance and mentoring have benefitted me in all facets of my life.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

Work hard towards your goals, but make sure you take time for other things in life. It is often easy to get bogged down in details, when there is so much more happening around you. Read every day. And lastly, seek out experts, ask questions, and don’t be afraid to actually ask those questions.