Mythology across civilisations is a testament to our fascination with flight. Though very different from the flight of birds, insects show remarkably variable and versatile movement in the air. As subset of muscles in insect thoraces called Indirect Flight Muscles act as the engine that powers the beating of wings. To understand how they work, researchers have investigated molecular details of their function, without adequately being to visualise the overall structure. The situation is akin to knowing the thermodynamics of an engine, with only a broad idea of how an engine is constructed but with few of the details. Technical limitations had prevented such research so far.
In our study, we have shown a way use use MicroCT scanning to visualise muscles inside insect thoraces, without deforming them in the process.
Among other things, we have found that a certain set of muscles required for flight grow with age, but do so differently in males and females. Further, it is not the molecular apparatus that causes contractions whose volume increases with age. This is probably what makes ageing muscles not work too well. We also saw that left and right muscles can have vastly different volumes.
Without this method that we developed in-house, such studies would not have been possible. These studies were on the darling of geneticists, the humble fruit fly. Combined with the power of genetics, this method may also help us understand human muscle diseases better. With an unparalleled combination of scale and resolution, we have seen the striking differences and remarkable similarities between the muscles of fruit flies and honey bees. We now seek flight design secrets from other insects as well as what we can learn about our own muscles, supported partly by this method.
Access the paper here: https://doi.org/10.1098/rsob.190087
The authors have also created some intriguing videos to demonstrate their research: