Experimental study on the fluid mechanics of blood sucking in the proboscis of a female mosquito

Female mosquitoes are known to have a magnificent micro-scale pumping system that can transport small quantities of blood very effectively. To understand the dynamic characteristics of blood flow inside female mosquitoes, the measurement technique that is capable of measuring instantaneous flow fields of a biological sample at micrometer scales is required. In this study, the blood-sucking flow inside a female mosquito's food canal was measured in vivo using a micro particle image velocimetry (micro-PIV) velocity field measurement technique with high-temporal resolution. The volumetric flow rate (Q) and the time-averaged feeding speed (V) based on the diameter of the food canal (D) was found to be 5.751×10^?3 mm³/s and 0.416 cm/s, respectively. Spectral analysis on the velocity waveform shows a clear peak at 6.1 Hz, indicating distinct pulsatile blood-sucking characteristics. The Womersley number (α) was about 0.117 and the velocity profile of the blood flow inside the proboscis has a parabolic Hagen–Poiseuille flow pattern when α is much smaller than 1.     

Antibody labelling of resilin in energy stores for jumping in plant sucking insects

The rubbery protein resilin appears to form an integral part of the energy storage structures that enable many insects to jump by using a catapult mechanism. In plant sucking bugs that jump (Hemiptera, Auchenorrhyncha), the energy generated by the slow contractions of huge thoracic jumping muscles is stored by bending composite bow-shaped parts of the internal thoracic skeleton. Sudden recoil of these bows powers the rapid and simultaneous movements of both hind legs that in turn propel a jump. Until now, identification of resilin at these storage sites has depended exclusively upon characteristics that may not be specific: its fluorescence when illuminated with specific wavelengths of ultraviolet (UV) light and extinction of that fluorescence at low pH. To consolidate identification we have labelled the cuticular structures involved with an antibody raised against a product of the Drosophila CG15920 gene. This encodes pro-resilin, the first exon of which was expressed in E. coli and used to raise the antibody. We show that in frozen sections from two species, the antibody labels precisely those parts of the metathoracic energy stores that fluoresce under UV illumination. The presence of resilin in these insects is thus now further supported by a molecular criterion that is immunohistochemically specific.     

Feeding mechanics in primitive teleosts and in the halecomorph fish Amia calva

The mechanics of feeding in Salmo gairdneri and Hoplias malabaricus, two generalized predaceous teleosts, was studied using high-speed movies (200 frames per second). In Hoplias, the feeding mechanism is characterized by an extreme anterior swing of the maxilla and rapid depression of the hyoid occurring synchronously with mandibular depression and neurocranial elevation. A similar feeding sequence is observed in Salmo although the movements of the head are neither as extreme nor as rapid.
The anterior swing of the maxilla, usually attributed to mandibular depression, increased when the ligamentous connection of the maxilla to the mandible was severed. A mechanical model of the jaw was constructed to elucidate the functional interrelationships of the neurocranium, maxilla and mandible.
Films of the "holostean" Amia calva feeding show that the feeding mechanism is of a fundamentally different nature than that of primitive teleost fishes. Extreme anterior swinging of the maxilla occurs synchronously with jaw opening but branchiostegal expansion and hyoid depression only reach a maximum well after the jaws have begun to close. The existence of a highly efficient levator operculi—opercular series—mandible coupling is hypothesized on the basis of the rapid initial jaw opening.
This pattern of feeding movements in Amia has necessitated a revision of current theories on the nature and significance of the "holostean"     

巴氏新小绥螨对柑桔全爪螨处理的枳橙叶片挥发物的行为反应

【目的】研究巴氏新小绥螨Neoseiulus barkeri对柑桔全爪螨Panonychus citri及刺吸式昆虫为害柑桔叶片释放的挥发物的行为反应,揭示巴氏新小绥螨的嗅觉反应特点。【方法】采用GC-MS顶空进样法对枳橙叶片常见挥发性化合物、针刺枳橙叶片及其柑桔全爪螨雌成螨取食枳橙叶片挥发物进行定性分析,确定每类化合物的相对保留指数,构建枳橙叶片常见及受害挥发性化合物特征谱库。利用嗅觉测定技术分析巴氏新小绥螨对枳橙叶片挥发物的行为反应。【结果】针刺处理和柑桔全爪螨取食影响枳橙叶片挥发物的组成和含量。两种方法处理时枳橙叶片释放的主要物质为α-蒎烯、水芹烯、4-异丙基甲苯。随着处理加重,增量释放的物质为:cis-π-罗勒烯、月桂烯、柠檬烯、异松油烯,减量表达的物质为2-乙基-1-乙醇和十一烷。在10~(-2)、10~(-4)、10~(-6)和10~(-8)g/m L浓度下,正己醛、正壬醛、乙酸辛酯和正庚醛对巴氏新小绥螨有强烈的引诱作用(P>0.05);月桂烯在10~(-2)、10~(-4)和10~(-6)g/m L浓度下对巴氏新小绥螨有强烈的引诱作用(P>0.05);正壬醇和正辛醇随着浓度增加,对巴氏新小绥螨的引诱作用降低;苯甲醛对巴氏新小绥螨的引诱作用较弱。【结论】巴氏新小绥螨对柑桔全爪螨及刺吸式口器昆虫为害柑桔叶片释放出的挥发物各组分具有不同的行为反应,柑桔及其刺吸式害虫生境中的嗅觉线索在巴氏新小绥螨的寄主定位和生境选择中起着重要作用。     

Feeding strategy and locomotion of Cambrian hyolithides

The Chengjiang (Cambrian Stage 3) and Balang (Cambrian Stage 4) Konservat-Lagerstätten of South China have produced abundant hyolithide hyoliths; however, little attention has been paid to their feeding strategy and the role it played in the ecosystem. Hyolithides preserved in coprolites from the Chengjiang Biota and associated with a Tuzoia carcass from the Balang Fauna reveal the fluid feces consuming and scavenging strategies of this group. Size distribution of hyolithides demonstrates that their dietary habit is ontogenetically dependent, with juveniles having ingested organic-rich material whereas adult food consumption was more likely by a variety of species-dependent methods The first discovery of hyolithides in association with locomotion traces and burrows indicates they were not only epibenthic vagrants, but also shallow horizontal burrowers. The new discoveries reported herein enhance our understanding of the feeding strategy and other behaviours of Cambrian hyolithides.     

Cold adaptation strategy in insects inhabiting central Yakutia

Cold hardiness in 20 insect species living in extremely cold climate of Yakutia has been investigated for the first time. It was shown that the Yakutian insects prefer to use the strategy of freeze tolerance according to which they produce special substances initiating the freezing of hemolymph at high subzero temperatures. The presence of ice-nucleating agents in the haemolymph of insects belonging to the phylogenetic group of Lepidopteran was shown. We postulate that Pieris rapae may shift between the different cold hardiness strategies when they move from moderately cold regions to a more severe environment.     

森林冠层食叶昆虫取食水平的定量方法与研究进展

森林冠层叶片被取食水平具有高度的时空变异性.本文论述了定量冠层昆虫取食水平的研究意义和方法,分析了各类取样方法和技术的优缺点,并对国内相关研究案例进行了评述.本文将定量冠层食叶昆虫取食水平的研究方法区分为针对绿叶样品的方法和针对落叶样品的方法.对冠层内绿叶的取样包括破坏性采叶法和原位连续观测法,依据取样技术又可分为基于地面的取样技术和基于冠层的取样技术.针对落叶样品的研究方法是指通过对林分内的凋落叶进行系统性采样、测定叶面积缺失比例、继而评估林分尺度上冠层昆虫取食水平的方法.文末提出了与森林昆虫取食相关的3个重点研究领域.     

Red blood cell mechanics and capillary blood rheology

Blood contains a high vol fraction of erythrocytes (red blood cells), which strongly influence its flow properties. Much is known about the mechanical properties of red cells, providing a basis for understanding and predicting the rheological behavior of blood in terms of the behavior of individual red cells. This review describes quantitative theoretical models that relate red cell mechanics to flow properties of blood in capillaries. Red cells often flow in single file in capillaries, and rheological parameters can then be estimated by analyzing the motion and deformation of an individual red cell and the surrounding plasma in a capillary. The analysis may be simplified by using lubrication theory to approximate the plasma flow in the narrow gaps between the cells and the vessel walls. If red cell shapes are assumed to be axisymmetric, apparent viscosities are predicted that agree with determinations in glass capillaries. Red cells flowing in microvessels typically assume nonaxisymmetric shapes, with cyclic “tank-treading” motion of the membrane around the interior. Several analyses have been carried out that take these effects into account. These analyses indicate that nonaxisymmetry and tank-treading do not significantly influence the flow resistance in single-file or two-file flow.     

Feeding insects with a phytopathogenic fungus influences their diapause and population dynamics

Abstract.  1. A facultative mutualistic relationship between a herbivorous moth, Lobesia botrana , and a phytopathogenic fungus, Botrytis cinerea , both damaging the same plant, the vine, has been demonstrated recently. Laboratory and field studies were carried out to determine the influence of the presence of the fungus in food on larvae during the pre- and post-diapause periods and on the global fitness of the insect.
2. During the pre-diapause period, larvae fed on fungus exhibited a higher survival rate and a faster larval development than insects reared without fungus.
3. After the wintering diapause, insects reared with fungus displayed a better synchronisation of adult emergence and an increased fecundity compared with control insects.
4. These results indicate that food containing fungus provides an improved diet, permitting the herbivorous insect to obtain nutrients required to optimise their life-history traits.
5. In addition, the results emphasise the importance of the nutritional quality of larval diet, improved by addition of the fungus, on diapause termination and on the demography of the insect before and after the wintering diapause.     

昆虫对转Bt杀虫蛋白基因植物的抗性及其对策

1 引言 苏云金杆菌(Bacillus thuringiensis 简称Bt)是目前世界上产量最大、应用最为成功的微生物杀虫剂,除了已筛选出多种Bt菌株直接发酵培养外,还培育出转基因工程菌及转基因植物,使Bt的使用范围大为扩大. Bt在形成芽孢时产生的伴孢晶体是Bt杀虫活性的主要来源,它可能由几种晶体蛋白即δ-内毒素组成,包括Cry和Cyt两大类.一般认为,δ-内毒素的作用过程要经溶解、酶解活化、与受体结合、插入和孔洞或离子通道形成等五个环节[1],涉及到多种毒素和作用位点,单一因素的改变对其敏感性影响不大,自50年代到80年代初Bt应用的30多年里,均未有昆虫对之产生抗性的报道,以至于一些研究者曾过分乐观地认为昆虫对Bt 不会产生抗性.进入80年代后,情况发生了急剧变化,相继发现五带淡色库蚊(Culex qu inquefasciatusg)、印度谷螟(Plodia interpunctella)等多种昆虫对Bt产生了抗体[2],同时在田间也发现世界性蔬菜害虫小菜蛾(Plutella xylostella) 对Bt产生了抗生[3-4],世界各国相继开展了昆虫对Bt产生抗性的条件和机制的研究,以期在昆虫还未普遍对Bt产生抗性之前,制定出相应的防治策略,这对于Bt制剂,尤其是转Bt工程菌和转Bt植物的推广使用,具有十分重要的意义.     

Red blood cell mechanics and capillary blood rheology.

Blood contains a high vol fraction of erythrocytes (red blood cells), which strongly influence its flow properties. Much is known about the mechanical properties of red cells, providing a basis for understanding and predicting the rheological behavior of blood in terms of the behavior of individual red cells. This review describes quantitative theoretical models that relate red cell mechanics to flow properties of blood in capillaries. Red cells often flow in single file in capillaries, and rheological parameters can then be estimated by analyzing the motion and deformation of an individual red cell and the surrounding plasma in a capillary. The analysis may be simplified by using lubrication theory to approximate the plasma flow in the narrow gaps between the cells and the vessels walls. If red cell shapes are assumed to be axisymmetric, apparent viscosities are predicted that agree with determinations in glass capillaries. Red cells flowing in microvessels typically assume nonaxisymmetric shapes, with cyclic "tank-treading" motion of the membrane around the interior. Several analyses have been carried out that take these effects into account. These analyses indicate that nonaxisymmetry and tank-treading do not significantly influence the flow resistance in single-file or two-file flow.     

Multiscale modeling of red blood cell mechanics and blood flow in malaria

Red blood cells (RBCs) infected by a Plasmodium parasite in malaria may lose their membrane deformability with a relative membrane stiffening more than ten-fold in comparison with healthy RBCs leading to potential capillary occlusions. Moreover, infected RBCs are able to adhere to other healthy and parasitized cells and to the vascular endothelium resulting in a substantial disruption of normal blood circulation. In the present work, we simulate infected RBCs in malaria using a multiscale RBC model based on the dissipative particle dynamics method, coupling scales at the sub-cellular level with scales at the vessel size. Our objective is to conduct a full validation of the RBC model with a diverse set of experimental data, including temperature dependence, and to identify the limitations of this purely mechanistic model. The simulated elastic deformations of parasitized RBCs match those obtained in optical-tweezers experiments for different stages of intra-erythrocytic parasite development. The rheological properties of RBCs in malaria are compared with those obtained by optical magnetic twisting cytometry and by monitoring membrane fluctuations at room, physiological, and febrile temperatures. We also study the dynamics of infected RBCs in Poiseuille flow in comparison with healthy cells and present validated bulk viscosity predictions of malaria-infected blood for a wide range of parasitemia levels (percentage of infected RBCs with respect to the total number of cells in a unit volume).     

Development of a treatment threshold for sucking insects in determinate Bollgard II transgenic cotton grown in winter production areas

Abstract  Little is known about the impact of sucking insects on cotton grown in tropical production areas. To examine this, an experiment was conducted at Katherine in northern Australia to determine the impact of mirids ( Creontiades dilutus (Stål) and Creontiades pacificus (Stål), green vegetable bug ( Nezara veridula (L.)) and red-banded shield bug ( Piezodorus hybneri (Gmelin)) on the yield and fibre quality of the transgenic cotton variety DP50bx containing genes for the expression of Cry1A(c) and Cry2A(b) δ-endotoxins of Bacillus thuringiensis Berliner variety kurstaki . The trial examined the impact of sucking insect populations in the range 0.5–2.0/m². Yields of unsprayed plots were approximately 30% of those obtained in plots sprayed on a threshold of 0.5/m² which did not differ significantly from plots sprayed regularly to exclude sucking insects. The increase in yield in the low pest density treatments was the result of improved fruit retention in the middle part of the plant. Fibre quality was similar in all treatments. However, damage ratings to individual bolls did differ between treatments. Bolls in the high insect density treatments received more damage than those in the low density treatments. As a result of this study, a tentative treatment threshold of 0.5 sucking insect/m² is recommended in determinate Bollgard II cotton varieties grown in winter production areas.     

转基因棉花主要靶标害虫的抗性发展及抗性治理策略研究

转基因棉花的大面积种植有效的控制了棉铃虫Helicoverpa armigera、红铃虫Pectinophora gossypiella 等靶标害虫的危害,然而抗性监测结果显示,转Bt基因棉田的棉铃虫耐受性正逐年提高,抗性问题已成为影响持续利用转Bt基因棉花的主要因素,发展新的转基因棉花势在必行.新的基因或蛋白的选择应以对靶标害虫高效、不易产生抗性,且与现在广泛应用的基因或蛋白无交互抗性为原则.本文综述了转Bt基因棉花的主要靶标害虫对Bt抗性的研究进展,及其与新抗虫转基因棉花的关系,并讨论了抗性治理策略的发展历程.     

Reproductive strategy of insects as adaptation to temporally varying environments

Diversity of oviposition curve observed in 125 insects was analysed using the ratio of the length of period for development to that for reproduction. On the basis of this empirical data, two extreme reproductive patterns were selected: prolonged reproduction with early maturity and concentrated reproduction with late maturity. Population growth of the species with each reproductive pattern was calculated usingLeslie Matrix under some simulated fluctuating environments where the length of time during which the environments change is short compared with the time required to stabilize age structure. These simulation studies show that there is an optimal ratio of the length of period for development to that for reproduction in achieving high population densities and this ratio varies depending on the favorableness of environment for reproductive success: as the environmental favorableness decreases, the optimal ratio becomes larger.     

Lung mechanics and blood gases in pregnant guinea pigs

Lung resistance and compliance were measured in early pregnant, late pregnant and non pregnant guinea pigs. Lung resistance was increased, lung compliance was decreased in pregnancy. A new finding was the increase of chest wall compliance in the course of pregnancy. In order to obtain a sufficient gas exchange during artificial ventilation, pregnant animals have to be ventilated with a higher frequency or a higher pressure than non pregnant controls.