Insects discover secret of their wax layer: protection and communication combined!

Insects discover secret of their wax layer: protection and communication combined!

In a recent study, researchers from the universities of Mainz and Paris Cité examined the physical properties of the wax layer of insects. This layer, composed of cuticular hydrocarbons (CHCs), plays a crucial role in protection against desiccation and chemical communication among insects. The study, published in the renowned journal Journal of the Royal Society Interface published shows for the first time that the liquid phase of this wax layer has two different viscosities.

What is particularly interesting is that the thick part of the wax layer resembles honey, while the thin phase looks like olive oil. This complex phase behavior allows insects to simultaneously meet their chemical communication needs and protect themselves from water loss. This is particularly relevant as insect populations are declining globally, partly due to global warming and the associated high temperatures, which increase fluid loss through the animals' chitinous shells.

Physical properties and their meaning

The researchers examined the viscosity of the wax layer as a function of temperature. Ants kept at 28 degrees Celsius showed higher viscosity compared to samples kept at 20 degrees. This temperature dependence underlines the ability of insects to adjust the chemical composition of their wax layer in order to effectively protect themselves against drying out. A more viscous layer provides better protection, while a thinner composition is important for chemical communication.

The study compared the viscosity of the wax layer with that of motor oil. This is remarkable because the phenomenon has been observed in eleven different ant species, each with different mixtures of substances in their CHCs. The connection between the chemical composition of the wax layer and its viscosity could be crucial for recognizing nest mates and defending against enemies.

Wax layer as an evolutionary factor

The wax layer does not have a fixed melting point, but rather a liquid melting range of around -45 °C to +30 to 40 °C. This phenomenon, studied by differential scanning calorimetry, shows that the CHCs exist in a liquid-solid mixture. This condition is crucial for their functions as it ensures both protection against desiccation and enables effective communication between insects.

The results of this interdisciplinary research open up new perspectives for understanding the biological functions of the wax layer. In view of the noticeable decline in insects, also as a result of climate change, understanding these mechanisms is of central importance. Future studies will focus on further examining the viscosity and melting behavior of the CHCs at different temperatures over a three-week period to better understand the evolutionary implications.

Overall, the new findings make it clear that protection against desiccation and the needs for communication are in a dynamic balance that is essential for the survival of ants. Further research is necessary to consistently analyze the adaptation mechanisms of insects in times of change.