School of Pharmacy and Molecular Sciences, James Cook University, Townsville, QLD 4811, Australia.
J Struct Biol. 2010 Jul;171(1):44-51. doi: 10.1016/j.jsb.2010.03.008. Epub 2010 Mar 27.
Non-wetting surfaces help in the survival of terrestrial and semi-aquatic insects. Some insects encounter wetting by rain, through contact with water collected on foliage, or in ponds, rivers or streams. There is an evolutionary pay-off for such insects to adopt hydrophobic structuring especially on regions that contact water, such as legs or large surface areas such as wings. Here we investigate lacewings which are good candidates for getting trapped to water because of a large wing surface area-to-body mass ratio. The lacewing utilises a variety of structures/mechanisms to contend with water contact. The first level involves small hairs (macrotrichia) that project from veins on the wings and collectively hold up droplets of water above the wing surface. This defence against wetting is aided by longitudinal ridges and troughs along the hair shaft. We show, by coating single hairs with a hydrophobic polymer (similar in hydrophobicity to insect cuticle), that the channels significantly contribute to repel water droplets. Beneath the array of hairs lies a dense netting on the cuticle wing surface which reduces contact with smaller droplets. The study has implications for both insect biology and biomimetic surfaces such as light weight superhydrophobic materials.
非润湿表面有助于陆生和半水生昆虫的生存。一些昆虫会遇到雨水的润湿，通过与叶片上收集的水接触，或者在池塘、河流或溪流中遇到水。对于这些昆虫来说，采用疏水结构是有进化收益的，特别是在与水接触的区域，例如腿部或像翅膀这样的大表面积区域。在这里，我们研究了那些由于较大的翅膀表面积与体重比而容易被水困住的草蛉。草蛉利用各种结构/机制来应对与水的接触。第一层涉及从翅膀的脉上伸出的小毛发（macrotrichia），它们将水滴托在翅膀表面上方。这种抗润湿的防御措施得益于毛发轴上的纵向脊和槽。我们通过用疏水性聚合物（与昆虫表皮疏水性相似）涂覆单根毛发，表明这些通道对排斥液滴有很大的贡献。在毛发阵列的下方是在表皮翅膀表面上的密集网，这减少了与较小液滴的接触。这项研究对昆虫生物学和仿生表面都有影响，例如重量轻的超疏水材料。
