Wolff Jonas O, Lovtsova Julia, Gorb Elena, Dai Zhendong, Ji Aihong, Zhao Zhihui, Jiang Nan, Gorb Stanislav N
Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
Entomological Museum, All-Russian Center for Plant Quarantine, Moscow, Russia.
J R Soc Interface. 2017 Mar;14(128). doi: 10.1098/rsif.2017.0007.
Silks play an important role in the life of various arthropods. A highly neglected prerequisite to make versatile use of silks is sufficient attachment to substrates. Although there have been some studies on the structure and mechanics of silk anchorages of spiders, for insects only anecdotal reports on attachment-associated spinning behaviour exist. Here, we experimentally studied the silk attachment of the pupae and last instar caterpillars of the tea bagworm (Butler 1881) (Lepidoptera, Psychidae) to the leaves of its host plant We found that the bagworms spin attachment discs, which share some structural features with those of spiders, like a plaque consisting of numerous overlaid, looped glue-coated silk fibres and the medially attaching suspension thread. Although the glue, which coats the fibres, cannot spread and adhere very well to the leaf surface, high pull-off forces were measured, yielding a mean safety factor (force divided by the animal weight) of 385.6. Presumably, the bagworms achieve this by removal of the leaf epidermis prior to silk attachment, which exposes the underlying tissue that represents a much better bonding site. This ensures a reliable attachment during the immobile, vulnerable pupal stage. This is the first study on the biomechanics and structure of silk attachments to substrates in insects.
丝在各种节肢动物的生活中起着重要作用。充分附着于基质是广泛利用丝的一个极易被忽视的前提条件。尽管已经有一些关于蜘蛛丝附着结构和力学的研究，但对于昆虫，仅有关于与附着相关的吐丝行为的零星报道。在此，我们通过实验研究了茶袋蛾（巴特勒，1881年）（鳞翅目，蓑蛾科）蛹和末龄幼虫与其寄主植物叶片之间的丝附着情况。我们发现，袋蛾会纺出附着盘，其与蜘蛛的附着盘具有一些共同的结构特征，比如一个由众多重叠、成环且涂有胶水的丝纤维组成的板块以及中间附着的悬线。尽管涂覆在纤维上的胶水不能很好地铺展并附着在叶片表面，但仍测得较高的拉脱力，平均安全系数（力除以动物体重）为385.6。据推测，袋蛾是通过在丝附着之前去除叶片表皮来实现这一点的，这样就暴露出了下面的组织，而这是一个更好的黏附位点。这确保了在不动且易受伤害的蛹期能有可靠的附着。这是关于昆虫丝与基质附着的生物力学和结构的首次研究。
