Chemical composition: Hearing insect defensive volatiles

ABSTRACT: Summary Chemical signals mediate major ecological interactions in insects. However, using bioassays only, it is difficult to quantify the bioactivity of complex mixtures, such as volatile defensive secretions emitted by prey insects, and to assess the impact of single compounds on the repellence of the entire mixture. To represent chemical data in a different perceptive mode, we used a process of sonification by parameter mapping of single molecules, which translated chemical signals into acoustic signals. These sounds were then mixed at dB levels reflecting the relative concentrations of the molecules within species-specific secretions. Repellence of single volatiles, as well as mixtures of volatiles, against predators were significantly correlated with the repulsiveness of their respective auditory translates against humans, who mainly reacted to sound pressure. Furthermore, sound pressure and predator response were associated with the number of different molecules in a secretion. Our transmodal approach, from olfactory to auditory perception, offers further prospects for chemo-ecological research and data representation. Highlights • The defensive secretion emitted by insects is often a mixture of volatiles• Volatiles were translated into sounds by sonification using parameter mapping• Chemical signals were repulsive for predators, as were the sounds for humans The bigger picture Insects are often defended against predators by emitting volatile secretions that act as a repellent. Chemical analyses of a secretion provide a list of compounds and their concentrations, but it then remains challenging to study their single and combined bioactivities. Here, we provide a first approach in understanding the bioactivity of single volatiles and volatile mixtures by developing a process of sonification (parameter mapping) to model chemical signals into auditory ones. Our study reveals via bioassays that foraging predators are repelled by volatiles as are human volunteers upon hearing "sonified volatiles". In these audio clips, we could also identify one sound attribute, their maximal loudness, that correlates well with the human response in the modeled world and hence with the predator response in the real world. These findings may help in exploring and understanding the seemingly overabundant diversity of deleterious chemicals present in insects and other organisms. A methodology is described to predict and compare the interspecific repellence of defensive secretions from insects that typically emit volatiles as complex mixtures. Sonification by parameter mapping allowed us to hear single molecules, then their mixtures. Bioassays used insect predators tested against the two sets of stimuli, single and mixed volatiles, as well as humans hearing the corresponding auditory translates. The model based on gathered chemical data can serve as a proxy but quantitative indicator of repellent bioactivities.

SUBMITTER: Boeve J 

PROVIDER: S-EPMC8600227 | biostudies-literature |

REPOSITORIES: biostudies-literature