To many people, insects don’t exactly come across as “sophisticated” animals. However, there’s more than meets the eye when it comes to these small creatures. The amazing navigation systems of insects, such as the “waggle dance” of bees to communicate direction, or the scent trails of ants, have been studied for decades. Today, we will be taking a closer look at some of the more “neuro” reasons behind a few insect navigation behaviors.
Ants are eusocial organisms, meaning that the majority of them do not reproduce, and provide labor and services to an individual that does reproduce, known in ants as the “queen”. Some would say that the setup of an ant colony can allow all the ants to function as one big organism. Individual ants rely little on vision (their optic lobe is quite small, except for individuals that can fly and therefore need to see where they’re going in midair). Instead, they rely on chemoreception, using their antennae to sense chemicals. The corresponding lobe (antennal lobe) is extremely complex complex. Although little is actually known about the ant nervous system, it’s not hard to see that chemoreception plays a large part in ant colony navigation. When ants are foraging and an individual finds food to share with the colony, they leave a chemical scent trail from the food item back to the nest. The other colony members will then pick up the trail using their antennae and follow it towards the food item and back to the nest again, using very little vision. The chemical information is processed in the aforementioned antennal lobe, which sadly has not been studied enough for us to know anything about the actual neurons firing.
Honey bees have an ability called path integration, in which they can measure the turns they make during their search for food, and are then able to “compile” these paths into a straight line from the food source back to their home. This ability is also found in some species of ant. However, bees that are kept in an area without food can have their internal compass “reset”, and instead of flying towards home, they will fly in a straight line as if they are leaving the hive and returning to a food source. The area without food has become “home” for the bee. As it turns out, the bee’s navigation system is not without flaws. When bees were deprived of food during a study period, they flew when released in the exact opposite direction of their hive. But when the bees were fed, they flew straight home. The bees seems to be using hunger cues to know which way to fly. A well fed bee assumes it needs to be flying home, and a hungry bee assumes it should be leaving home. Although their paths are accurate, their directions are not.
A common feature of many insects’ internal navigational system is their reliance on spatial memory to create a “cognitive map”, or using the locations of specific nearby objects (called “landmarks”) to determine where other things are, such as a nest or a food source. This has been noted in bees as well as wasps, however, although ants clearly have a navigational system, evidence of cognitive maps has not been seen in ants. Remember that ants have a very small optic lobe and do not rely very much on sight while navigating, so it makes sense that they do not seem to use landmarks to determine where they are.
Although there is much research done on insect navigation, it tends to lean more towards the “etho” side, and very little of it focuses on the “neuro” side. This is definitely an area of research that has room to expand upon. If you consider yourself an insect fan, this may be something you’d like to check out in the future!
Dyer, Fred, et al. “Motivation and Vector Navigation in Honey Bees.” Naturwissenschaften, vol. 89, no. 6, 2002, pp. 262–264., doi:10.1007/s00114-002-0311-5.
Gronenberg, Wulfila. “Neuroethology of Ants.” Naturwissenschaften, vol. 83, no. 1, 1996, pp. 15–27., doi:10.1007/s001140050240.
Wystrach, Antoine, and Paul Graham. “What Can We Learn from Studies of Insect Navigation?” Animal Behaviour, vol. 84, no. 1, 2012, pp. 13–20., doi:10.1016/j.anbehav.2012.04.017.