Catcher in the cave - Fishing strategy of a Jamaican fungus gnat Neoditomyia farri

There is a continual need for bonding substances that can be used in wound heeling (hard and soft tissue) as well as in medical or dental implants. Unfortunately, today`s synthetic adhesives often have the disadvantage of exhibiting a reduced range of application or of being highly toxic. The development of new, specific adhesive polymers based on natural adhesives (keyword "bionic") is an important aspect in material research and offers an opportunity for new medical applications. These biological adhesives differ clearly in their structure, composition and function from synthetically manufactured products. Nevertheless, our knowledge about the composition and characteristics of most biological adhesives is still marginal and limited. Insects use adhesives in highly diverse ways. The best-known function is the use of adhesive threads to capture prey. So far, most knowledge about these adhesives is based on spiders; detailed investigations in other insect groups are largely missing. The present investigation offers, for the first time, the possibility to characterize the adhesive composition and bonding mechanisms in dipterans in detail. The planned research project deals with the morphology of the adhesive glands in the dipterian species Neoditomyia farri and focuses the biochemical analyses on the composition and function of these adhesives. The results are expected to characterize the sticking mechanism and to determine the chemical nature of the adhesives. Beyond the biochemical results on the structure and function of the adhesives, the results will provide the basis for new biomimetic applications in industry and medicine.

Animals use adhesives in various ways. The most prominent system is permanent adhesion to the substratum, such as can be found in mussels, sea snails or sea urchins. In addition, adhesive is also used to catch prey, the best examples of which are surely the large webs of orb weaver spiders. In the present project we have for the first time characterized the structure and composition of the adhesive silk threads produced by the fungus gnat larvae Arachnocampa. These animals, found in New Zealand and Australia and also known as glowworms, are world-famous due to their ability to produce their own light (bioluminescence). As the animals mostly live deep within dark caves, they attract their prey (i.e. mayflies) using this light and catch them with a sticky curtain of silk threads. The present data show that the adhesive threads consist largely of water (>99%) and only bear a small proportion of salts, proteins and fats. Although the Arachnocampa threads exhibit lower tensile strength values than the silk threads of orb weavers, they are nevertheless perfectly adapted to the size and weight of the prey that flies into the cave. This projects outcome clearly shows how the animals have adapted both to the cave habitat and to the capture of their prey with less need of effort and resources.