Exploring silk dynamics data.csv

The study examines how silk produced by detritivores living in dry regions might differ from that of tropical arboreal webspinners (Embioptera). The detritivores are Haploembia tarsalis and Oligotoma nigra. The tropical species are Antipaluria urichi and Pararhagadochir trinitatis. Webspinners rely on silk for protection, including from rain and flooding. They spin the finest silks known in nature. The amino acid compositions vary from one species to the next and might impact how the silk interacts with water. Fiber diameter also varies, whereby the detritivores spin finer silks (approximately 48 nm diameter) than the arboreals (72 - 122 nm). Water-silk interactions are known for Embioptera, as the fibers transform to a film when wetted. In either case, the silk protects the insects within the silk galleries from water. Silk was imaged by SEM and quantified as density based on pixels using ImageJ Fiji. After exposure to water, the silk surface transforms to a film; the film density was quantified the same way as were the dry fibers. Disappearance rates of the water droplets placed on silk was recorded and revealed that the one species (Oligotoma nigra) with hydrophobic silk amino acids showed the slowest transformation rate when exposed to water. The two arboreal species showed higher density of spun silk fibers and of the resulting silk films after wetting compared to the detritivores. Possible adaptive value is that the tropical species rely more on a thick silk coating as protection from natural enemies and from heavy rainfall. Embioptera silk is not well studied; further work is needed to elucidate the variability as demonstrated by this preliminary investigation of silk diversity. Contact angle of drops on spun silk were also measured for 7uL drops of water..本研究旨在探究干旱地区食腐昆虫所产蚕丝，与热带树栖纺足目（Embioptera）昆虫所产蚕丝的差异。供试的食腐昆虫为Haploembia tarsalis与Oligotoma nigra，热带树栖物种为Antipaluria urichi与Pararhagadochir trinitatis。纺足目昆虫依靠蚕丝实现防护，包括抵御降雨与洪涝灾害，其所纺制的蚕丝是自然界已知最纤细的丝类。不同物种的蚕丝氨基酸组成存在种间差异，这可能会影响蚕丝与水的相互作用。纤维直径同样存在种间变异：食腐昆虫所纺蚕丝的直径约为48 nm，而树栖热带物种的蚕丝直径为72~122 nm。目前学界已对纺足目蚕丝与水的相互作用有所研究——当纤维被浸湿时，会转变为薄膜状结构，两类群的蚕丝均可保护栖息于蚕丝廊道中的昆虫免受水害。本研究采用扫描电子显微镜（SEM）对蚕丝进行成像，并利用ImageJ Fiji软件基于像素对纤维密度进行定量分析。经水浸润后，蚕丝表面会转变为薄膜，其薄膜密度的定量分析方法与干燥纤维一致。研究人员记录了滴加在蚕丝表面的水滴的消失速率，结果显示，Oligotoma nigra的蚕丝氨基酸组成具有疏水性，其在浸水后的纤维向薄膜转变的速率最慢。两种树栖热带物种所纺制的蚕丝纤维，及其浸润后形成的蚕丝薄膜，其密度均高于食腐干旱地区物种。其潜在的适应价值在于：热带树栖纺足目更依赖厚实的蚕丝涂层，以抵御天敌与强降雨。目前针对纺足目蚕丝的研究尚不完善，本初步调查已展现出蚕丝多样性的变异特征，后续仍需开展更多工作以阐明其变异机制。本研究还对7微升水滴在纺制蚕丝表面的接触角进行了测量。