Surface chemistry of the ladybird beetle adhesive foot fluid across various substrates

Parasitoid attachment ability and the host surface wettability

Climbing animals such as geckos and arthropods developed astonishing adhesive mechanisms which are fundamental for their survival and represent valuable models for biomimetic purposes. A firm adhesion to the host surface, in order to successfully lay eggs is necessary for the reproduction of most parasitoid insects. In the present study, we performed a comparative investigation on the attachment ability of four parasitoid species (the egg parasitoid Anastatus bifasciatus (Eupelmidae), the aphid parasitoid Aphidius ervi (Braconidae), the fly pupal ectoparasitoid Muscidifurax raptorellus (Pteromalidae) and the pupal parasitoid of Drosophila Trichopria drosophilae (Diapriidae)) with hosts characterized by a surface having different wettability properties. The friction force measurements were performed on smooth artificial (glass) surfaces showing different contact angles of water. We found that attachment systems of parasitoid insects are tuned to match the wettability of the host surface. Sexual dimorphism in the attachment ability of some tested species has been also observed. The obtained results are probably related to different microstructure and chemical composition of the host surfaces and to different chemical composition of the parasitoid adhesive fluid. The data here presented can be interpreted as an adaptation, especially in the female, to the physicochemical properties of the host surface and contribute to shed light on the coevolutionary processes of parasitoid insects and their hosts.

Bio-inspired materials to control and minimise insect attachment

More than three quarters of all animal species on Earth are insects, successfully inhabiting most ecosystems on the planet. Due to their opulence, insects provide the backbone of many biological processes, but also inflict adverse impacts on agricultural and stored products, buildings and human health. To countermeasure insect pests, the interactions of these animals with their surroundings have to be fully understood. This review focuses on the various forms of insect attachment, natural surfaces that have evolved to counter insect adhesion, and particularly features recently developed synthetic bio-inspired solutions. These bio-inspired solutions often enhance the variety of applicable mechanisms observed in nature and open paths for improved technological solutions that are needed in a changing global society.

Bio-inspired adhesion control with liquids

Bio-inspired surfaces enabling wet adhesion management are of significant interest for applications in the field of biomedicine, as components of bionic robots and as wearable devices. In the course of biological evolution, many organisms have evolved wet adhesive surfaces with strong attachment ability. Insects enhance their adhesion on contact substrates using secreted adhesive liquids. Here we discuss concepts of bio-inspired wet adhesion. First, remaining challenges associated with the understanding and the design of biological and artificial wet adhesive systems as well as strategies to supply adhesive liquids to their contact surfaces are reviewed. Then, future directions to construct wet adhesive surfaces with liquids are discussed in detail. Finally, a model of wet adhesion management with liquids is suggested, which might help the design of next-generation bio-inspired wet adhesive surfaces.