You probably saw this title and thought to yourself, “Has Kristen lost her mind? What do ants, aphids, and elephants have in common? And why is an entomologist talking about a pachyderm, because elephants are certainly not insects.” This is a subject close to my heart and is rather interesting, so humor me for a moment. During my time in college, I took a study abroad trip to Kenya. While I was there, I researched elephants, ants, and acacia trees. In the ecosystem I studied, ants and acacia trees share what’s called a symbiotic relationship, meaning that they help each other out. In Kenya, these acacia trees are widely prevalent in some areas, and elephants find them to be a tasty treat. They will use their muscular trunks to twist off the branches and leaves. However, like many living things, these acacia trees want to stay alive, not die because of a hungry elephant. This is where ants come into play.
The ants chemically influence the acacia tree to make large galls on itself so that the ants have a happy home on the tree. What is a gall? A gall is a ball-shaped growth that protrudes from the tree limbs. Acacia trees are not the only plant that insects will chemically influence to create galls, but for the acacia tree specifically, they make these galls for the ants that live in them. The tree is happy to provide these homes for the ants because they play an important role in protecting the tree from elephants! Although it may seem crazy that a tiny ant can defend a tree from an elephant, the ants’ strength lies in their numbers. When elephants approach the tree with their trunks and start to twist the tree, the ants will inundate their trunks, stinging them and making the elephants extremely uncomfortable. The elephants will then retreat, allowing the tree to live to see another day. The tree provides a home for the ant, and the ant provides protection for the tree; this symbiotic relationship is critical for protecting biodiversity in a Kenyan ecosystem.
Where do we see this same type of relationship here in our own backyards? To give a clue, this is where the aphids come into play. Aphids are common insects found around the world and most likely somewhere outside your home. They are tiny little insects and are about the size of a pinhead in some cases. They are plant feeders, so they will eat from the undersides of leaves in bushes. As they feed on these bushes, they create honeydew, which causes a mold-like appearance on the topsides of leaves and ultimately kills the host plant. Although aphids are detrimental to whatever they feed on, they are vulnerable to other insect-feeding insects. This is where ants come in again.
Ants and aphids have a symbiotic relationship similar to the one that ants and acacia trees share in Kenya. One of my favorite movies is A Bug’s Life. In the movie, the queen ant carries around a little insect with her named Aphie. If the name doesn’t clue you in, her pet is an aphid. Just like you would take care of your pet cat or dog, she takes care of this aphid and tends to it. This is not unlike the relationship between ants and aphids in nature. That honeydew that aphids produce is a yummy snack for ants, so in return for the food, ants will protect aphids. Although we do not necessarily want either of these insects around our homes, they are very important to each other.
Symbiotic relationships are found across the globe in various ecosystems. However, knowing about them can often help us eliminate pests around your home. If you are seeing ants that regular treatments are not working as well to control, then we need to think outside the box and remember, for instance, the relationship of ants and aphids. Perhaps there are aphids nearby providing the ants a yummy food source, and once we eliminate the aphids, this could help to control the ant issue. Now you can (re)watch A Bug’s Life while you’re sitting at home and think of all that you have learned about symbiotic relationships!
Kristen Stevens, BCE