Kamal Ghorui
Scientific discoveries don’t necessarily emerge from laboratories. In this case, it came out of a back garden. An 8-year-old child named Hugo Deans observed round bodies around an ant hill, thinking he had discovered some seeds. However, they turned out to be oak galls created by wasps on the oaks.This observation marked the beginning of a study carried out by Penn State University and SUNY. It was then that the previously unknown link between ants, wasps, and oak trees was found. The discovery was published in The American Naturalist, illustrating the value of the seemingly obvious questions posed by kids.What are oak galls?The name of these peculiar structures reflects their source. Oak galls represent round bodies created by some types of wasps laying eggs inside the plant. They develop under the plant’s response to a chemical substance secreted by the mother insect during egg-laying.They typically fall down to the earth along with the leaves in autumn. Until recently, scientists considered them only as shelters for the larvae of different insects. Now, we know that there is more behind them.It didn’t take long before Hugo’s father, Andrew Deans, an entomologist at Penn State University, realised what those items actually were. What puzzled him the most about those insects wasn’t the galls, but rather the ants transporting them.Normal ant behaviorIn general, ants are well-known for collecting seeds from plants in a process of seed dispersal by ants, called myrmecochory. It turns out that many seeds have a fat body inside them called an elaiosome.Professor Andrew Deans said that ants obtain some nourishment from consuming the elaiosomes, whereas the plants obtain dispersed seeds. This natural phenomenon has been known for more than a hundred years and is one of the basics of biology classes.In such cases, ants transport seeds to their nests, eat the nutrient-filled part and leave the other portion safe somewhere else to germinate.
A backyard discovery that changed how scientists see ant behaviour. Image credit – Wikimedia
Similarity of the processesThe latest findings demonstrated that ants treated galls in a manner similar to the above process. Scientists examined galls formed by two wasp species, Kokkocynips rileyi and Kokkocynips decidua. The galls had a small cap-shaped organ, which was named “kapéllo” from the Greek word “hat”.Ants in field experiments were able to collect the galls in a way similar to that with which they gathered the seeds. Laboratory experiments confirmed that ants had equal preference for both objects.The crucial role belongs to the kapéllo. Without it, ants paid little attention to the galls. With the presence of the cap, ants transported them.Chemical nature of the phenomenonThe scientists investigated the chemical composition of the kapéllo, and they discovered that it contains fatty acids identical to those contained in elaiosomes. Oleic acid, palmitic acid, and stearic acid belong to such compounds known for triggering ants’ activity.As the authors state, this chemical similarity serves as an attractive sign to ants that suggests the object is valuable enough to gather. Gas chromatographic analysis revealed that the chemical properties of the kapéllo coincide with the preferred seed structures by ants.Why kapello feels relevant to waspsUnlike seeds, wasps have no need for ants in their dispersal. Mature wasps can fly. Here, it seems, is the advantage.Nests built by ants are underground and have antimicrobial elements. Such nests will provide protection for the developing larvae against potential threats such as predators, parasites, and even fungi.The researchers conclude that the wasps have adapted themselves so that they can modify the plant tissues in such a way that the tissues attract ants. It can be said that the phenomenon described above is convergent evolution, which means that multiple species developed similar adaptations to solve a particular problem.A secret web right under our noseThe study extends our knowledge of biological relationships between different species. The research revealed that not only plants but other organisms can use ant transportation systems by imitating plant tissues.It can be said that these findings give us additional insight into possible influence of ants on forest ecosystems. The movement of galls made by insects underground may impact nutrient and microorganism cycles.The child’s role in the scientific discoveryHugo Deans is another case where an observation played an important role. The boy did not intend to refute any theory. He just happened to notice something interesting. Hugo thought they were seeds, according to what he recalled from the moment of his observation.This phenomenon is now considered another illustration of communication among organisms using chemistry. This is an example that confirms the idea that even the most studied systems can have something new to discover.An inspiration for curiosityThe discovery of this phenomenon did not require any highly sophisticated technology initially. Everything started with paying attention and being curious. Later on, scientists employed various methods such as chemical analysis and experiments.The message is simple – nature is full of complicated structures even within our vicinity. For the rest of us, it means that seemingly insignificant discoveries can become significant. In this particular case, the curiosity of a kid led to the discovery of an unknown connection between ants, wasps, and plants.
