Surviving submerged—Setal tracheal gills for gas exchange in adult rheophilic diving beetles

The gas exchange in adult diving beetles (Coleoptera: Dytiscidae) relies on a subelytral air store, which has to be renewed in regular intervals at the water surface. The dive duration varies from a few minutes to 24 h depending on the species, activity, and temperature. However, some species remain submerged for several weeks. Stygobiont species do not ascend to the surface and gas exchange of these species remains unclear, but it is assumed that they require air filled voids for respiration or they use cutaneous respiration. In this study, we investigate the gas exchange in the running water diving beetle Deronectes aubei, which survive submerged for over 6 weeks. The diffusion distance through the cuticle is too great for cutaneous respiration. Therefore, the dissolved oxygen uptake of submerged beetles was determined and an oxygen uptake via the rich tracheated elytra was observed. Fine structure analyses (SEM and TEM) of the beetles showed tracheated setae mainly on the elytral surface, which acts as tracheal gills. Prevention of the air bubble formation at the tip of the abdomen, which normally act as physical gill in Dytiscidae, resulted in no effect in oxygen uptake in D. aubei, but this was the sole way for a submerged Hydroporus palustris to get oxygen. The setal gas exchange technique explains the restriction of D. aubei to rivers and brooks with high oxygen concentration and it may also be used by subterran living diving beetles, which lack access to atmospheric oxygen. The existence of setal tracheal gills in species in running water which are often found in the hyporheic zone and in stygobiont species supports the known evolution of stygobiont Dytiscidae from species of the hyporheic zone. For species in running water, setal tracheal gills could be seen as an adaptation to avoid drifting downstream by the current. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

纹吉丁属及其近缘种鞘翅超微结构的比较研究(鞘翅目,吉丁科)

比较研究了8种纹吉丁和7种近缘属种类鞘翅刻点的超微结构,研究表明纹吉丁属鞘翅刻点结构具有属、种特异性.纹吉丁属不同种类鞘翅刻点的形态相似,仅大小、密度和弯曲程度不同.纹吉丁与其近缘属种类鞘翅刻点的形态结构差异显著.同时表明,外部形态相似的类群,鞘翅刻点的形态结构未必相似,体现了吉丁鞘翅形态结构的多样性.     

独角仙前翅中的小柱分布及其前翅表面的微细构造

从仿生学的角度,通过研究习行动物翅膀的力学特性,在航天航空业界的构造设计上获得有益的启示。用扫描电子显微镜及爱射光,考察了独角仙前翅的微细构造。结果为考察方法及昆虫形态学,特别是有关独角仙前翅小柱分布及其前翅表面的微细构造方面,亦得到了一些新的见解;1）将甲虫前翅置于透过光下,甲虫前翅上的小柱呈黑点状。用此方法,探明了独角仙前翅中的小柱,除了延气管两侧有点近似直线的排列之外,均为无规律分布,此种分布规律不同于以往所认识的其它种类甲虫所具有特征：小柱以直线分布,并且与小柱对应的前翅表面有凹穴作标记。2）在独角仙前翅内部,存在着肉状（蜂窝状）的构造。此种构造通常在一蜂窝状构造上有1－2上柱,每个蜂窝上小柱根数和蜂窝的大小有关,并且小柱主要分布于蜂窝的角中（蜂窝状构造是航空等许多业界已经广泛采用的工业化了的优良构造,甲虫在此基础上用柱子进行强化,此种强化构造有可能给相关业界的构造设计带来有益的启示。     

Asynchronous temporal variation among sites in condition of two carabid species

Abstract.  1. It is generally assumed that generalist predatory carabids are food limited, and the degree of food limitation can vary in space and time, but there are only a few studies that investigate whether or not temporal variation in insect condition is synchronised among sites.
2. In this paper temporal and spatial variation in four fitness-related traits – body mass corrected for size, body size, fat content, and fecundity – of two carabid species, Pterostichus cupreus (L.) and Pterostichus melanarius (Ill.), differing in overwintering strategy, lifespan, diet, and habitat breadth were studied.
3. Interactions between temporal and spatial variation for the fitness-related traits were found for both species. Temporal changes in food limitation were not synchronised among sites, and fitness-related traits were not generally higher on some sites than on others.
4. There was an effect of study year on body mass, fat content, and fecundity for both species, suggesting that temporal environmental variation over large areas is more important than the spatial environmental variation within a year.
5. Within a time period, most different fitness-related traits, except body size, were positively correlated to each other among individuals of the same species. The fitness-related traits of females and males of the same species were generally positively correlated. However, despite the fact that the food resources of the two species overlap, there was no correlation in fitness-related traits between the two species.     

甲虫(独角仙和鍬形虫)前翅中的小柱微细构造(英文)

为了从仿生学的角度 ,获得复合材料构造的最优化设计的指导思想 ,用扫描电子显微镜考察了独角仙和锹形虫前翅中的小柱微细构造 ,结果在昆虫形态学方面也得到了一些新的见解 :1 )与甲虫前翅上下层相连的小柱 ,其形状和尺寸的大小因甲虫种类而异。不过 ,和以往的认识不同的是 ,两种甲虫前翅的小柱具有类似的结构 ,它们均为非中空的实柱 ,并由中心部和环状的几丁质纤维层构成。其中心部主要是溶解于KOH溶液的物质 (蛋白一类的物质 ) ,环状纤维层中的几丁质纤维 ,在层和层之间相互不同的方向排列着 ,并各自与前翅的上下层中的几丁质纤维连续地连接着 ;2 )独角仙前翅小柱的表面有复杂的纹样 ,而锹形虫的小柱表面只有非常简单的 (几乎没有 )纹样。此外 ,业已证明 ,上述的小柱构造对层状纤维强化复合材料而言 ,的确是一种非常巧妙的 ,可极其有效地提高复合材料抗剥离性能的生体构造。     

Relationship between phenotypic traits and selected fitness components of Diabrotica virgifera virgifera

Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is one of the most important and best-studied maize pests, yet little information is available regarding the basic relationships among its phenotypic traits, particularly those that reflect the overall fitness of this successful invader in Europe and North America. Such information is critical for studies on the invasiveness, behavioural ecology, and management of this pest. Phenotypic traits that change over the lifetime of the beetle were investigated (e.g., fresh body weight) as they can indicate changes in adult physiology or fitness of D. v. virgifera . Phenotypic traits that remain stable over the beetle's lifetime were also investigated (e.g., pronotum width, head capsule width, hind tibia length), as they most likely allow detection of genetic differences between populations. Furthermore, phenotypic traits were investigated that may best predict fecundity (e.g., fresh body weight, elytra width) and life span (e.g., elytra length), as these two factors influence the population growth of this highly invasive species. Finally, regression equations are provided for the age-specific oviposition and survival of the long-living D. v. virgifera adults, which may allow researchers to reduce the duration of their bioassays without losing information.     

外源补充多巴胺对异色瓢虫突变体gr生长发育及鞘翅颜色的影响

异色瓢虫Harmonia axyridis是我国常见的一种捕食性天敌昆虫,其基于黑色素的体色在环境适应中发挥着重要作用.多巴胺(dopamine,DA)是昆虫合成黑色素的一类重要前体物质,同时在调节生理活动方面具有重要作用,但尚不清楚多巴胺在异色瓢虫生长发育中的作用.本实验室前期发现一异色瓢虫浅色突变体gr,其体色的黑化程度明显浅于野生型.本研究以该突变体为研究对象,以添加不同浓度DA的人工饲料(10 mg/g(D-H)、1 mg/g(D-M)、与0.1 mg/g(D-L))饲养幼虫,测定生长发育相关参数及新羽化成虫的鞘翅颜色参数.结果显示:桃蚜Myzus persicae饲喂至2龄的gr取食对照饲料后无法成功发育至3龄,而取食添加DA的饲料后可发育至4龄,但不同饲料间的存活率无显著差异,同时D-L处理的3龄幼虫发育时间显著短于D-H与D-M.桃蚜饲喂至4龄后取食人工饲料,D-M处理的化蛹率、羽化率、雌雄虫体重及鞘翅黑色斑点的Brightness值均高于其它两种饲料及对照处理,并且D-L处理新羽化成虫鞘翅黑色斑点的Brightness值最小(颜色最黑).上述结果表明DA在异色瓢虫幼虫生长发育中具有重要作用,但受浓度影响;幼虫期补充DA可影响成虫鞘翅颜色.     

Passive aerodynamic stabilization by beetle elytra (wing covers)

Summary. Most beetles extend their elytra laterally during flight, where they can act as fixed airfoils; typically, such elytra are held at a pronounced dihedral angle. We fixed extended elytra of June beetles (Scarabaeidae: Melolonthinae) and tiger beetles (Cicindelidae) over a range of dihedral angles (-10° to 45°) and towed them in a water tunnel. We also towed them with flexed elytra (i.e. in the resting position). (Reynolds number was used to maintain dynamic similarity with air.) We measured the maximum rolling angle and the lateral oscillation rate as two indices of stability. There was no relationship between oscillation rate and dihedral angle, or between maximum roll angle and dihedral angle. At all dihedral angles tested, however, beetles were much more stable than when they were towed with the elytra flexed. We also included a third beetle type, flower beetle (Scarabaeidae: Cetoniine), which normally flies with flexed elytra. We measured stability indices for these beetles with elytra only in the flexed position. When all beetles were tested with flexed elytra, flower beetles showed no difference in maximum roll angle, but more stability in oscillation rate than the other two beetle types.     

Mechanical and Frictional Properties of the Elytra of Five Species of Beetles

The mechanical and frictional properties of different parts of the elytra of five species of beetle were measured using a nano-indenter and a micro-tribometer. The surface microstructures of the elytra were observed by optical microscopy and scanning white light interferometry. The surface microstructures of the elytra of all five species are characterized as non-smooth concavo-convex although specific morphological differences demonstrate the diversity of beetle elytra. Young's modulus and the hardness of the elytral materials vary with the species of beetle and the sampling locations, ranging from 1.80 GPa to 12.44 GPa, and from 0.24 GPa to 0.75 GPa, respectively. In general, both the Young's modulus and the hardness are lower in samples taken from the center of the elytra than those taken from other regions, which reflects the functional heterogeneity of biological material in the process of biological evolution. The elytra have very low friction coefficient, ranging from 0.037 to 0.079, which is related to their composition and morphology. Our measurements indicate that the surface texture and its microstructural size of beetle elytra contribute to anti-friction effects.     

A natural flightless mutation in the ladybird, Harmonia axyridis

A homozygous flightless strain, obtained by selection from a laboratory population of Harmonia axyridis Pallas (Coleoptera, Coccinellidae), has been reared under controlled conditions since 1982 after sampling in China. The adults of this flightless strain have normal elytra and wings but drop almost vertically when they attempt to fly. The origin of this mutation, whether laboratory or natural, is discussed. As the mutation does not affect the fitness of the beetles, this flightless strain can be used in biological control. Releasing flightless adults rather than larvae should provide the potential for more continuous control of aphids by both larvae and adults.