昆虫体内两种不同的抗性机制

阐述了昆虫体内存在的两种不同的抗性机制,即基因扩增引起的抗药性（pre－adaptive）和杀虫剂诱导引起的抗药性（post—adaptive）。前者可遗传,后者虽不遗传,但能加速抗性发展和产生交叉抗性。     

Meniscus-climbing insects

Water-walking insects and spiders rely on surface tension for static weight support and use a variety of means to propel themselves along the surface. To pass from the water surface to land, they must contend with the slippery slopes of the menisci that border the water's edge. The ability to climb menisci is a skill exploited by water-walking insects as they seek land in order to lay eggs or avoid predators; moreover, it was a necessary adaptation for their ancestors as they evolved from terrestrials to live exclusively on the water surface. Many millimetre-scale water-walking insects are unable to climb menisci using their traditional means of propulsion. Through a combined experimental and theoretical study, here we investigate the meniscus-climbing technique that such insects use. By assuming a fixed body posture, they deform the water surface in order to generate capillary forces: they thus propel themselves laterally without moving their appendages. We develop a theoretical model for this novel mode of propulsion and use it to rationalize the climbers' characteristic body postures and predict climbing trajectories consistent with those reported here and elsewhere.