Investigating the foot adhesion chemistry of ladybird beetles

Part of the reason bugs can crawl sideways and upside down is due to special chemicals on their feet, which allow them to stick to a variety of different surfaces. Fowler et al. investigated the chemistry behind these bioadhesive fluids for a seven-spotted ladybird beetle, an insect whose large body size, relatively common occurrence, and excellent bioadhesion performance allow for a rigorous and reproducible study of insect-feet adhesion.

Researchers from Oregon State University and University of Kiel identify the components of the beetle’s fluids that directly interact with a surface and show how the molecular environment at the fluid-substrate interface changes as the insects interact with substrates with increasing hydrophobicities.

“Insect adhesive fluids have evolved highly specific compositions, which are consistent across most surfaces, and optimize both foot adhesion and release in natural environments,” co-author Joe Baio said.

To probe the surface chemistry of these adhesive fluids, the authors used sum frequency generation spectroscopy, a surface-sensitive technique that can probe biological interfaces in aqueous environments without the need for complicated sample preparation.

Using the technique, the team characterized the chemical environment of the fluid-substrate interface with molecular resolution. This allowed the researchers to determine the relationship between surface wettability and order of adhesive molecules in the beetle’s foot fluid.

Baio said the authors plan to continue the study by characterizing the parts of the beetle’s foot fluid that are not interacting with the surface.

“We think that the chemistry of the bulk, surface-inactive fluid plays an equally important role in the regulation of the magnitude of traction forces generated during this adhesion process,” Baio said.

Source: “Surface chemistry of the ladybird beetle adhesive foot fluid across various substrates,” by James Elliott Fowler, Johannes Franz, Thaddeus W. Golbek, Tobias Weidner, Elena Gorb, Stanislav Gorb, and Joe E. Baio, Biointerphases (2021). The article can be accessed at https://doi.org/10.1116/6.0001006 .

This paper is part of the Biomimetics of Biointerfaces Collection, learn more here .