Biosensors Working Group
Prof. Dr. Andreas Vilcinskas
Semiochemicals are chemicals that carry messages between organisms. Communication via semiochemicals is an important branch of chemical ecology because this process allows the accurate transmission and reception of information that enhances survival. Insect antennae are the most sensitive sensory organs that have ever evolved for the perception of semiochemicals, because communication among insects can involve messages encoded by exquisitely low doses of scent substances. Such biosensors allow insects to register the lowest concentrations of a particular scent molecule (e.g. representing the presence of food or a sexual partner) and to follow them along concentration gradients across huge distances to find the source. Even individual molecules can induce electrical impulses in the insect olfactory system, and these are passed on to the brain for processing.
Electroantennography is a method that can be used to measure the output of individual insect antennae. The sum of nerve impulses produced by the antennae is conducted through ultra-thin electrodes to an amplification system and thus recoded. The Biosensors Working Group combines electroantennographic detection (EAD), gas chromatography (GC) and mass spectrometry (MS) into a unique portable system that allows the quantitative and sensitive detection of complex mixtures of scents in the environment - exactly as they are found under normal environmental conditions. The inclusion of mass spectrometry provides useful information on the composition of the scent substances. Our portable GC-MS/EAD device can be used for in situ measurements in any location.
One example of the application of our research involves the European grapevine moth (Lobesia botrana), which causes significant damage in wine-growing regions but can be combated using the dispersions of certain pheromones. With the help of the antennae of L. botrana we can measure such pheromones in vineyards even if they are present at concentrations well below the detection limits of the most sensitive commercial devices. In order to broaden the applications of this low detection threshold, trained insects are used that can reliably indicate the presence of certain substances through defined and measurable behaviours.
We also carry out research on the development of biomimetic sensors, focusing on the identification of key substances that insects use to discern particular events. Among the complex scent mixtures found in nature, insects perceive only those substances that provide unambiguous information. Having deduced which substances are registered by their antennae, we can create corresponding measuring devices including the adjustment of semiconductor gas sensors in such a way that these substances can be measured more sensitively and selectively.
Our research also focuses on the identification of specific volatile defensive compounds. For example, we are currently investigating the quinone-rich secretions of different species of earwigs, components of which have been shown to inhibit particular bacteria, fungi and nematodes.