by Piter Kehoma Boll
There are more than 3000 species of cicada worldwide and they are often associated with the summer when they become adults and their songs can be heard coming from the trees. Today we will focus on an Australian species, Psaltoda claripennis, known as the clanger cicada.
The clanger cicada is found in eastern Australia and is common around in Brisbane and nearby areas, where it can be easily seen on tree branches, sometimes in groups. They have a brownish dorsum with some dark, sometimes black, segments in the abdomen. The ventral side is pale, except for the abdomen, which is brown, and the legs are yellow. The eyes are light red to brownish red and the wings are transparent with green veins. Males measure about 30 mm in length and females are slightly smaller, about 25 mm long.
I wasn’t able to find much information about its natural history. This species was actually just one more among many cicada species until some years ago when an interesting discovery was made.
Cicada wings are beautiful structures and are usually very clean. In fact, many insect species find ways to maintain their wings clean even in very contaminated environments and one of the reasons for it is that insects wings are extremely hydrophobic, i.e, they repel water just like many plant leaves. Since water has a hard time trying to attach to their wings, microorganisms associated with water cannot get to the wings either.
But the wings of the clanger cicada are more than only hydrophobic. Studies have shown that every cell of gram-negative bacteria that happens to touch the wing surface is deformed and dies. The same did not happen with gram-positive bacteria, though. As the studies progressed, researches started to understand the structural arrangement of the wings. Their surface is formed by very small pillars, only about 30 nm high and distant 170 nm from each other. When a gram-negative bacterium falls on those pillars, its soft membranes start to slide to the space between them and stretch enough to break. The poor cell ends up as a dead disformed mass. Gram-positive bacteria have more rigid cell walls and are resistant to stretch, but treating them with microwave decreased their rigidity and allowed them to be killed as well.
Further research on this structure can lead to the development of new materials that remain sterile even after contacting a pathogen.
Once more the diversity of lifeforms brought us ways to improve our society. How many more useful stuff are hidden in the forests and fields? Preserving the ecosystems is the best for every inhabitant of this planet.
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Xue F, Liu J, Guo L, Zhang L, Li Q (2015) Theoretical study on the bactericidal nature of nanopatterned surfaces. Journal of Theoretical Biology 385:1–7. https://doi.org/10.1016/j.jtbi.2015.08.011
Hasan J, Webb HK, Truong VK et al. (2013) Selective bactericidal activity of nanopatterned superhydrophobic cicada Psaltoda claripennis wing surfaces. Applied Microbiology and Biotechnologt 97:9257–9262. https://doi.org/10.1007/s00253-012-4628-5
Pogodin S, Hasan J, Baulin VA et.al. (2013) Biophysical Model of Bacterial Cell Interactions with Nanopatterned Cicada Wing Surfaces. Biophysical Journal 104(4): 835–840. https://doi.org/10.1016/j.bpj.2012.12.046