Numerical Analysis of the Adhesive Forces in Nano-Scale Structure

Nanohairs, which can be found on the epidermis of Tokay gecko＇s toes, contribute to the adhesion by means of van der Waals force, capillary force, etc. This structure has inspired many researchers to fabricate the attachable nano-scale structures. However, the efficiency of artificial nano-scale structures is not reliable sufficiently. Moreover, the mechanical parameters related to the nano-hair attachment are not yet revealed qualitatively. The mechanical parameters which have influence on the ability of adhesive nano-hairs were investigated through numerical simulation in which only van der Waals force was considered. For the numerical analysis, finite element method was utilized and van der Waals force, assumed as 12-6 Lennard-Jones potential, was implemented as the body force term in the finite element formulation.     

茄二十八星瓢虫在茄子叶片上垂直方向的附着力

本文采用电子天平称重法对茄二十八星瓢虫的2龄幼虫、3龄幼虫、4龄幼虫、雌成虫和雄成虫在茄子叶片上垂直方向的附着力进行测定,为进一步研发和利用气流控制技术防治农业害虫提供技术参数。研究结果表明,2龄幼虫、3龄幼虫、4龄幼虫、雌成虫和雄成虫垂直方向的最大附着力分别为7.3±0.3 mN,8.6±0.6 mN,12.0±0.3 mN,15.8±1.3 mN和13.0±1.0 mN。茄二十八星瓢虫垂直方向的附着力从大到小的顺序均为:雌成虫雄成虫;4龄幼虫3龄幼虫2龄幼虫。幼虫的附着力/虫体体重系数由大到小的顺序为:2龄幼虫3龄幼虫4龄幼虫,所有处理的附着力与虫体体重的相关性均不显著。附着力/虫体重量的系数范围为47.8-90.8,身体重量占附着力1.1%-2.1%。结果进一步表明,在设计旋风式气流吸虫机的频率等参数时,要考虑茄二十八星瓢虫在茄子叶片上的附着力远大于其体重的情况。     

日本刀角瓢虫对不同叶毛密度茄子品种的产卵选择性

【目的】产卵是昆虫发育过程中繁衍后代、维持种群数量的重要环节。在前期研究发现日本刀角瓢虫Serangium japonicum喜欢在茄子Solanum melongena叶片上产卵的前提下,本研究旨在深入探究日本刀角瓢虫对不同叶毛密度茄子品种的产卵选择性,以期进一步明确植物叶毛介导的日本刀角瓢虫产卵选择机制。【方法】观察日本刀角瓢虫雌成虫在4个茄子品种(黑到底、黑妞、日友长直壮、络星)叶碟和植株上的产卵选择性,测定不同茄子品种上日本刀角瓢虫后代的生长发育及成虫的繁殖力、捕食能力和对叶片的附着力,观察4个茄子品种叶片背面超微结构,测定日本刀角瓢虫雌成虫对茄子叶片的气味选择,测量茄子叶片上烟粉虱Bemisia tabaci卵粒的长度和宽度,测定日本刀角瓢虫卵被其雌成虫的同类捕食风险。【结果】日本刀角瓢虫偏好在黑到底上产卵,后代个体在黑到底品种上总发育历期(15.41±0.21 d)最短,亲代单雌产卵量(877.44±15.27粒/头)最高。但是,日本刀角瓢虫的产卵量占比与子代生长表现(发育历期、存活率和成虫体重)和成虫生存表现(繁殖力和捕食能力)均无显著相关性,而与叶片背面叶毛密度和长度存在显著正相关性;日本刀角瓢虫在茄子叶碟上的产卵量占比与日本刀角瓢虫雌成虫附着力存在显著正相关性。日本刀角瓢虫雌成虫附着力与叶毛密度显著正相关,而与亲代生长表现无显著相关关系。茄子叶片气味、猎物质量以及被同类捕食风险均不显著影响日本刀角瓢虫的产卵选择。【结论】茄子叶片背面叶毛密度及叶毛介导的日本刀角瓢虫附着力在日本刀角瓢虫对茄子叶片的产卵选择性中起重要作用。