Holding tight on feathers - structural specializations and attachment properties of the avian ectoparasiteCrataerina pallida(Diptera, Hippoboscidae)

Abstract

The louse fly is an obligate blood-sucking ectoparasite of the common swift As a result of reduction of the wings, is unable to fly; thus, an effective and reliable attachment to their host's plumage is of utmost importance. The attachment system of shows several modifications in comparison to that of other calyptrate flies, notably the large tridentate claws and the dichotomously shaped setae located on the pulvilli. Based on data from morphological analysis, confocal laser scanning microscopy, cryo-scanning electron microscopy and attachment force experiments performed on native (feathers) as well as artificial substrates (glass, epoxy resin and silicone rubber), we showed that the entire attachment system is highly adapted to the fly's lifestyle as an ectoparasite. The claws in particular are the main contributor to strong attachment to the host. Resulting attachment forces on feathers make it impossible to detach without damage to the feathers or to the legs of the louse fly itself. Well-developed pulvilli are responsible for the attachment to smooth surfaces. Both dichotomously shaped setae and high setal density explain high attachment forces observed on smooth substrates. For the first time, we demonstrate a material gradient within the setae, with soft, resilin-dominated apical tips and stiff, more sclerotized bases in Diptera. The empodium seems not to be directly involved in the attachment process, but it might operate as a cleaning device and may be essential to maintain the functionality of the entire attachment system.

Progress in Bioinspired Dry and Wet Gradient Materials from Design Principles to Engineering Applications

“…The results of these studies are similar to the results of some previous researches (Gorb et al, 2019;Vickers, 2017;Ballen et al, 2012;Magazù et al, 2005;Stork, 1980;Voigt et al, 2017). In addition, such gradient in the setal material composition have also been discovered in flies (Heepe et al, 2018;Petersen et al, 2018) and stink bugs (Rebora et al, 2018), suggesting a convergent evolution across different insect lineages (Gorb and Filippov, 2014). Nevertheless, the gradient distribution of Young's modulus of gecko seta and ladybird beetle are both formed by the gradient distribution of varied proteins.…”

Functional morphology of the raptorial forelegs in Mantispa styriaca (Insecta: Neuroptera)

“…Yet, Loxton and Nicholls (1979) indicated differences within the cuticle in Mantodea, due to either heavily sclerotized or thin and flexible cuticle at the base of femoral spines, that needs further investigation. However, the relevance of the material composition in a functional and/or biomechanical context, was shown in a number of studies for a variety of character systems in insects like: mouthparts (Büsse and Gorb 2018), thorax (Bäumler and Büsse 2019) or abdomen (Willkommen et al 2015), but most often for wings (Gorb 1999;Haas et al, 2000;Appel and Gorb 2011;Rajabi et al 2016) and legs (Peisker et al 2013;Jandausch et al 2018;Petersen et al 2018;Büsse et al 2019a, b). The main purpose of the study is therefore, to present a detailed description of the raptorial forelegs of Mantispa styriaca (Poda, 1761), including extrinsic and intrinsic musculature as well as the material composition of their cuticle.…”

Liquid secretion and setal compliance: the beetle's winning combination for a robust and reversible adhesion

“…Interestingly, similar gradients were also shown to occur in other hairy pads, e.g. flies [15] and stink bugs [16], suggesting a convergent evolution of this feature in various insect lineages [17]. For the further analysis, we restrict our discussion of insect adhesion to the hairy attachment system of beetles.…”