James Cook University researchers and collaborators have found the wing of the cicada kills bacteria solely through its physical structure — one of the first natural surfaces found to do so.
Their work has recently been published in Nature News, one of the world's most highly cited interdisciplinary science journals, as well as Scientific American, and on websites such as Science News Daily, among others.
Dr Gregory Watson, from JCU’s Scanning Probe Microscopy Facility in the School of Marine and Tropical Biology, provided the genesis of the research along with his wife, Dr Jolanta Watson.
The duo were part of an international team of researchers which has come up with a detailed model of how this anti-microbial defence works on the nanoscale.
Dr Watson said as two scientists, the cicada and insect world in general had proved fascinating.
“Being nanoscientists and biophysicists, we have been interested in the natural world of the very, very small from the start,” he said.
The cicada sparked their interest while walking through the bush one day more than a decade ago.
They found a dead cicada on the pathway and noticed that the wings did not reflect light.
They took it back to the lab to study it, and ended up collecting more cicadas.
“While collecting our cicadas, we’d noticed that the wings of the dead insects on the ground were not consumed or contaminated in the same manner as their bodies,” he said.
“As bacteria play such an important role in decomposition, we thought there may be something responsible for this effect. As well, we measured very little adhesion between the cicada wings and natural contaminants such as soil fragments and pollens using a sophisticated instrument called an atomic force microscope.
“So this combination, as well as intuition, provided the reasons for the studies of bacterial interactions with not only the cicada wings but also other insect wings.”
They contacted a collaborator down south who is a skilled microbiologist, and began to closely study how the nano-structures of the cicada wing interact with some bacteria.
The group of international researchers found the wings tear the bacteria membrane apart, which results in the bacterial death (anti-microbial).
Dr Watson said as insect wings often had many functions, they were investigating other possible functions of the wings and their nano-structures.
“Resistance to antibiotics is a world-wide challenge as a result of the serious implications for public health. Natural biological surfaces such as insect wings gives us an exciting opportunity for templates that we can use in the development of a wide range of novel antibacterial materials for industrial and especially biomedical applications. “
Dr Watson said for example, they had also recently been able to successfully grow human retinal cells on the cicada wings.
“This highlights the applications for these types of surfaces where we can kill bacteria but also have a surface which allows human and animal cells to grow. Such surfaces may find applications in human implants where there is a need to minimise post-surgery infections and promote wound healing,” he said.
“We have now looked at over 20 or so species. The species in the paper that was highlighted in the Nature News article is Psaltoda claripennis.
“More than 200 cicada species have been identified in Australia and being primarily tropical insects, most Australian species are found in the northern states with Queensland being one of the richest regions.”
The report in Nature News can be found here.