Lanterna Rally

Author: Matthew James Anyon

Publisher:

Published: 2013

Total Pages:

ISBN-13:

The ability of insects to successfully attach to a wide variety of surfaces with seemingly little to no effort has fascinated naturalists and researchers for hundreds of years. The observation of a fly climbing up a window, or spider walking upside down on our ceilings is a commonly overlooked and under-appreciated sight. The advanced ability of insects to attach themselves successfully to different surfaces for the purpose of locomotion, under different orientations and in a fast, reliable and efficient manner is not only an impressive natural capability but also crucial to the survival and ecology of the insect, and by extension to the success of the species as a whole. To achieve this adhesive ability insects utilise a 'wet' adhesive system, making use of specialised functional adhesive pad structures which deploy a liquid secretion to the contact zone which aids adhesion through capillary and viscous forces. These attachment pads can be loosely classified as either 'smooth' or 'hairy' and are found in most insect species studied to date. Predictions from a small number of simple theoretical models of insect attachment have been experimentally verified for a number of insects species, however, due to the vastness of the insect world, the exact physical mechanisms underlying insect adhesion for the majority of insects is still unclear. Through the use of qualitative and quantitative experiments of several species of ant (Hymenoptera; Formicidae) and ladybird (Coleoptera; Coccinellidae) we characterise the functional morphology of the attachment devices and properties of the adhesive secretion of smooth and fibrillar attachment devices found in these insects. In an effort to gain a greater understanding of the physical mechanism of wet insect adhesion to smooth surfaces, we compare in vivo force measurement results from several custom-built force measurement techniques with predictions from a number of theoretical contact-mechanic models under conditions of adhesion normal to, and friction forces tangential to the substrate. By varying the physico-chemical properties of the substrates within these experiments, and the orientation of the insects under investigation, the magnitudes of these contributions under different experimental conditions is determined, and the results are discussed in the context of the magnitudes of different surface forces that may be acting during adhesive and frictional detachment processes, as well as the influence of the substrate surface energy. By applying this understanding towards the investigation and development of novel antiadhesive surfaces for use in domestic and industrial settings, several methods of reducing or preventing insect attachment forces are investigated and discussed in the context of creating environmentally and ecologically friendly strategies of pest control. In summary this thesis provides evidence for links between the physico-chemical properties of a substrate and adhesive forces generated by insects during locomotion, and how an insects' adhesive ability on a particular substrate may influence their behaviour. Results from this study will be helpful in designing the next generation of smart adhesives, but could also lead to novel anti-adhesive barriers for environmentally friendly strategies of pest-control.