Fun with Science Club®


			Without seeing, leafminer parasites find their host. Beth Tyler 06.01.01 Leaf-mining insects lay their eggs inside leaves. The eggs hatch and then grow in the leaf until they come out of the leaf as adults. Apple tentiform leafminers, Phyllonorycter malella, lay their eggs on apple leaves. Other insects, Sympiesis sericeicornis, will lay their eggs in a leaf with growing leafminers. These Sympiesis sericeicornis eggs are parasites of leafminers, meaning they take food and space from the leafminers without giving anything in return. Growing leafminers are hidden in the leaves, so how do Sympiesis sericeicornis find them? Can the leafminers know when a parasite is near? Three scientists hypothesized that the leafminer parasites and the leafminer use vibrations on the leaf to know where the other species is. To test their hypothesis, the scientists videotaped the behavior of the parasites and the growing leafminers in a laboratory. To be able to see the leafminers in the leaves, they removed the bottom layer of the leaf and replaced it with clear plastic. This way they could observe and record the behavior of growing leafminers inside the leaves. When a parasite landed on a leaf, the scientists made systematic observations of the movements of the parasite and the growing leafminers. They found that when the leafminers moved inside the leaf, the parasite on the leaf stopped moving. Also, when the parasite got very close to where the leafminers were, the leafminers stopped moving. Because the insects cannot see each other, the scientists concluded that the insects use leaf vibrations created by movement to figure where the other species is. The parasite stops when the leafminers move so it can feel where they are and move in that direction. Likewise, when the parasite is close, the leafminers stop moving in order to prevent the parasite from figuring out where they are. Even though they cannot see each other, the growing leafminers and their parasites interact using leaf vibrations.


			Meyhofer, R., J. Casa, and S. Dorn. 1997. Vibration-mediated interactions in a host-parasitoid system. Proceedings of the Royal Society of London, Series B 264: 261-266.