Water Strider Research Articles

The ultrastructure of sperm and female sperm storage organs in the water strider Gerris lacustris L. (Heteroptera) and a possible example of genital coevolution

The fine structural organization of the male and the female inner reproductive apparatuses of the water-strider Gerris lacustris was studied. The sperm of the species shows a long helicoidal acrosome provided with longitudinal tubules, and a short nucleus. The flagellum is characterized by crescent mitochondrial derivatives and a 9 + 9 + 2 axoneme, as occurs in all Heteroptera. The female reproductive apparatus is characterized by an extremely long spermathecal duct, filled with sperm, which plays the role of the main sperm storage organ. The duct has a thin epithelium surrounded by a complex of secretory and duct-forming cells. The spermathecal duct flows into the gynatrial sac. This region, together with the fertilization chamber, exhibits a simple epithelium with deep apical plasma membrane invaginations, and it does not show conspicuous secretions. The basal cell region shows plasma membrane infoldings forming thin cytoplasmic bands hosting mitochondria and large intercellular spaces. This organization is typical of epithelia active in fluid reabsorption. Two lateral large gynatrial glands open into the gynatrial sac. Such glands also exhibit secretory and duct forming cells. The same structure of these glands is also present along the proximal region of the fecundation canal. The duct forming cells of these regions have very wide ducts with peculiar cuticular finger-like structures at their opening into the gland duct lumen. The results of the present study suggest the occurrence of a coevolution between the sperm and the spermathecal duct lengths.

Carotenoids of hemipteran insects, from the perspective of chemo-systematic and chemical ecological studies

Carotenoids of 47 species of insects belonging to Hemiptera, including 16 species of Sternorrhyncha (aphids and a whitefly), 11 species of Auchenorrhyncha (planthoppers, leafhoppers, and cicadas), and 20 species of Heteroptera (stink bugs, assassin bugs, water striders, water scorpions, water bugs, and backswimmers), were investigated from the viewpoints of chemo-systematic and chemical ecology. In aphids, carotenoids belonging to the torulene biosynthetic pathway such as β-zeacarotene, β,ψ-carotene, and torulene, and carotenoids with a γ-end group such as β,γ-carotene and γ,γ-carotene were identified. Carotenoids belonging the torulene biosynthetic pathway and with a γ-end group were also present in water striders. On the other hand, β-carotene, β-cryptoxanthin, and lutein, which originated from dietary plants, were present in both stink bugs and leafhoppers. Assassin bugs also accumulated carotenoids from dietary insects. Trace amounts of carotenoids were detected in cicadas. Carotenoids of insects belonging to Hemiptera well-reflect their ecological life histories.

Guided Water Strider Algorithm for Structural Damage Detection Using Incomplete Modal Data

Over the last decades, metaheuristic algorithms have become versatile tools for solving various engineering optimization problems. That is why their application for structural damage identification has attracted the attention of researchers in civil engineering. In this paper, a guided structural damage detection approach using the recently developed optimization algorithm, water strider algorithm (WSA), is applied to detect multiple damage cases in structures. To reduce the computational costs, modal strain energy as a sensitive characteristic is used to localize damage locations in structures and guide the optimization algorithm. Considering incomplete modal data, four numerical examples and two with-noise and noise-free scenarios are examined. The results indicate the applicability and accuracy of the WSA in structural damage detection compared to other algorithms.

A Multistage Damage Detection Approach Using Graph Theory and Water Strider Algorithm

Structures usually suffer from natural or artificial damages that might result in shortening their service life and even triggering their collapse. Therefore, vibrational damage detection methods, as cost-effective and nondestructive techniques, are widely investigated by researchers. In the present paper, the modal-strain energy-based two-stage method is enhanced, and a graph-theoretic hierarchical (GHM) method is proposed, which takes advantage of the modal strain energy-based index (MSEBI) and overcomes its potential drawbacks by identifying all damaged elements. This method assigns orders and allocates the computational resources to elements according to the MSEBI as well as the connections represented by a graph model. The water strider algorithm (WSA) is also utilized as an efficient new optimizer, and its results are compared with those of some other well-known algorithms. Several examples are used to substantiate the results and performance of the new GHM framework, showing that the new method outperforms the general classic method, especially when it is combined with the WSA optimizer.

Anti-wettability of Chemically and Physically Modified Glass Surfaces

The demand for new advanced functional materials has driven scientific work over the past decades. Nature has been inspiring in the creation of different types of self-cleaning and super repellent surfaces mimicking those of plants (lotus leaves), animals (shark skin) or insects (butterfly wings, water strider). To produce and maintain super repellent materials, chemical modification of the surface by using low surface energy materials such as fluoropolymers and/or siloxanes is necessary. Also, physical modification of surface roughness enhances super-repellency against various liquids. The surface roughness can be achieved e.g., by the deposition of nano particles (NPs) using Liquid Flame Spray (LFS). Industrial applications like paper coatings, oil-water separation, and microfluidic devices have benefited from the fabrication of super-hydrophobic surfaces by LFS. In our work, glass substrates were fluorinated by chemical vapor deposition (CVD) method, and others were additionally pre-coated with silica NPs by LFS. The coated glass surfaces were characterized for their anti-wettability by measuring the contact angles of water and compare that to bare glass. The influence of the produced coatings on the wettability of surface with different liquids was examined through measuring advancing/receding contact angles as well as the roll off angle. Results showed that compared to bare glass only fluorination of glass increased the water static contact angle from 18 to almost 112 . This is indicative of hydrophobic behaviour. Coating glass with silica NPs by LFS before fluorination, enhanced the water anti-wetting property for super hydrophobicity. LFS coating provided good oleophobic characteristic.

Hypergravity running: A “centrifugal track” for sprint-specific strength training

After having discovered that, unlike humans, greyhounds do not slow down when running round a tight bend (Usherwood & Wilson, 2005 – https://doi.org/10.1038/438753a), desert lizards actually swim in the Sahara (Crofts & Summers, 2011 – https://doi.org/10.1038/472177a) and water strider insects are able to jump on water (Koh et al., 2015 – https://doi.org/10.1126/science.aab1637), we are now going to find out how sprint-running athletes can improve their strength capabilities by running under an augmented gravitational acceleration similar to that of Jupiter without actually having to leave Earth. The centrifugal track exploits the centripetal acceleration to increase the runner’s body weight during the foot-contact phase of running. Since inertial forces are distributed, the overload produced by running on the centrifugal track does not harmfully affect the musculoskeletal system. It has been shown that this overload does not cause acute detrimental changes to the running technique. The centrifugal track can be proposed as a viable alternative to traditional sprint-specific strength training tools.

Chemical Fabrication Strategies for Achieving Bioinspired Superhydrophobic Surfaces with Micro and Nanostructures: A Review

Biological surfaces in nature, such as lotus leaves, rose petals, and water striders, exhibit excellent superhydrophobicity. The fabrication of superhydrophobic surfaces inspired by nature has become an important research topic. The potential application of superhydrophobic surfaces in many fields has promoted the rapid development of fabrication techniques. Various chemical methods, such as chemical vapor deposition techniques, solution immersion methods, electrochemical techniques, hydrothermal method, and sol–gel process, have been proposed for fabricating superhydrophobic surfaces due to their low cost, simple preparation, and easy promotion. Herein, the progress of chemical fabrication methods of superhydrophobic surfaces in recent years is focused on and the strengths and weaknesses of each technique are analyzed. At last, a brief conclusion of the challenges and perspectives on the fabrication of superhydrophobic surfaces is provided.

How Can Interfacial Phenomena in Nature Inspire Smaller Robots

AbstractIn nature, surfaces are evolutionarily designed to allow adaptation of species to their environments. Insects make extensive use of interfacial phenomena because of their small size and thus, large surface‐area‐to‐volume ratio. This enables them to walk on different terrains, dive, swim, and adhere to surfaces in air and underwater. Moreover, they toggle between different interfaces, move in confined spaces, and overcome a wide range of obstacles. This progress report summarizes emerging directions in the field of bioinspired robotics with an emphasis on micro and nanoscale dynamic interactions. It is envisioned that interfacial phenomena will allow to miniaturize robots and increase the complexity of their operation. The key to success is the combination of functional surfaces, structural design and multiple modes of locomotion. For this to be realized, however, new paradigms are needed in terms of materials, fabrication, energy consumption, and actuation. This report discusses the development of small robots inspired by water striders, the bell spider, the leaf and ladybird beetles, backswimmers and cockroaches, among many others. It also discusses small soft robots inspired by roundworms, larvae, and parasites. From a broader perspective, fabrication of many small robots will enable to study collective effects and self‐assembly, group behavior and swarming.

Allometry and Condition factor of Whipfin Silverbiddy, Gerres filamentosus from Mangalore Coast, Karnataka, India

Background: Gerrids under family Gerridae are important in contributing rich source of protein. Gerres species are economically important food in India. They take a good role in development and economic of Indian estuaries. In fish biology, knowledge of the length-weight data and condition factor (Kn) is an important tool. Gerres filamentosus is one of the economically important groups of fishes inhabiting Karnataka coast. It was selected as a candidate for the present study since the knowledge on length-weight data and condition factor will be helpful in mass culture and production of this species in Karnataka.Methods: The length-weight relationships and condition factor of 2020 specimens of fish, G. filamentosus from Mangalore, Karnataka, south west coast of India, were studied from July 2009 to June 2011. The length-weight relationship was found using parabolic equation. Analysis of co-variance was used to test the significant difference in estimates of “b” between sexes. The condition factor for individual fish was calculated using the formula Kn = Wo/Wc.Result: The relation between the total length (L) and total weight (TW) was described as LogTW = -1.7716 + 2.9511 Log L for females, Log TW = -1.7526 + 2.9364 LogL for males and LogTW = -1.8343 + 2.9720 LogL for indeterminate fishes. The highest and lowest condition factor (Kn) values in females was in December 2010 (1.1186) and September 2010 (0.8871), respectively. Similarly, the highest and lowest Kn values in male was in March 2011 (1.0630) and September 2010 (0.6977), respectively. The result of length-weight relationships could be used for fishery to approve appropriate regulations for sustainable fishery management. The present findings could also be useful for ecosystem modeling. In the present study, changes in Kn value may be in relation to some other reasons than reproductive cycle and feeding intensity.

Water strider females use individual experience to adjust jumping behaviour to their weight within physical constraints of water surface tension

Different species of water striders match leg speeds to their body sizes to maximize their jump take off velocity without breaking the water surface, which might have aided evolution of leg structures optimized for exploitation of the water surface tension. It is not understood how water striders achieve this match. Can individuals modify their leg movements based on their body mass and locomotor experience? Here we tested if water striders, Gerris latiabdominis, adjust jumping behaviour based on their personal experience and how an experimentally added body weight affects this process. Females, but not males, modified their jumping behaviour in weight-dependent manner, but only when they experienced frequent jumping. They did so within the environmental constraint set by the physics of water surface tension. Females’ ability to adjust jumping may represent their adaptation to frequent increases or decreases of the weight that they support as mating bouts, during which males ride on top of females, start or end, respectively. This suggests that natural selection for optimized biomechanics combined with sexual selection for mating adaptations shapes this ability to optimally exploit water surface tension, which might have aided adaptive radiation of Gerromorpha into a diversity of semiaquatic niches.

Oviposition and refractory periods of the small water strider Microvelia horvathi (Heteroptera: Veliidae) after a single mating event

AbstractMultiple mating can be costly, but also beneficial for females. When the costs outweigh the benefits, mated females can be reluctant to remate for some time. Conversely, females will be likely to remate when they need to replenish sperm and/or receive nutrients contained in the accessory ejaculate substances. Water striders have been commonly used in mating studies as many show a vigorous struggle between the sexes. Generally, water strider females frequently mate with many males and lay many eggs during mating period. However, little is known about their oviposition and refractory periods after an initial mating event. In this study, we revealed that single‐mated females of the small water strider, Microvelia horvathi, could lay eggs for 40 days, reflecting approximately half of their potential oviposition periods. It suggested that M. horvathi females do not need to mate to replenish sperm for some time once they mate. Our results also showed that no female remated after 1 or 3 days of an initial mating event. The proportion of female remating increased with time after the initial mating, however, remating levels reached 26.7% even after 14 days. In this sense, any significant cost of mating outweighs the benefit, which might be one of the factors lowering their remating levels.

An open-source framework for the FE modeling and optimal design of fiber-steered variable-stiffness composite cylinders using water strider algorithm

As the automated fiber placement (AFP) manufacturing technology is developed, curvilinear fiber path composite structures received extensive attention. Therefore, developing a design framework capable of optimizing such structures is a significant challenge for researchers and engineers in this domain. In this article, an open-source ABAQUS/MATLAB-based framework is developed for the bending-induced buckling design of variable-stiffness (VS) composite cylinders made using the AFP method. The framework is based on an interface between ABAQUS FE packages with MATLAB environment using Python scripting language. In this framework, the optimized fiber angle distribution of steered plies and associated bending-induced buckling load of its FE model is obtained by applying a meta-heuristic optimization algorithm. The developed Python script submits dimensions, angle distributions, as well as loading and boundary conditions to ABAQUS/CAE. This framework can be customized to meet industrial demands. To show such flexibility, different types of metaheuristic optimization algorithms and aspect ratios are applied, and the associated problems are optimized separately. In addition to the simplicity and versatility of the proposed framework, the results indicate the higher performance of a novel metaheuristic, the so-called Water Strider Algorithm (WSA). Moreover, this framework can be used for finite element modeling and analysis in the metamodeling step for composite cylinders with higher aspect ratios.

Are population isolations and declines a threat to island endemic water striders? A lesson from demographic and niche modelling of Metrocoris esakii (Hemiptera: Gerridae).

Genetic stochasticity and bottlenecking in the course of Pleistocene glaciations have been identified as threatening the survival of local endemics. However, the mechanisms by which local endemic species balance the influences of these two events remain poorly understood. Here, we generated a double-digest restriction site-associated DNA sequencing (ddRAD-seq) data set, mined mitochondrial sequences and constructed ecological niche models for the island endemic water strider Metrocoris esakii (Hemiptera: Gerridae). We found that M. esakii comprised three divergent lineages (i.e., north, central and south) isolated by geographical barriers and generally experienced population declines with the constriction of suitable areas during the Last Glacial Maximum (LGM). Further demographic model testing and stairway plots revealed a history of recent gene flow among the neighbouring lineages and rapid recovery at the end of the LGM, indicating that M. esakii at least had the potential for an adaptive response to population fragmentation and bottlenecking. The northern lineage did not show genetic bottlenecking during the LGM, which was probably due to its large effective population size (Ne ) from migration, which improved its adaptive potential. Relative to the ddRAD-seq data set, the demographic results based on mitochondrial sequences were less conclusive, showing weak differentiation and oversimplified demographic trajectories for the three genetic lineages. Overall, this study provides some degree of optimism for the survival of island endemic water striders from a demographic perspective, but further evaluation of their extinction risk under the impacts of human activities is required.

An Improved Water Strider Algorithm for Optimal Design of Skeletal Structures

Water Strider Algorithm (WSA) is a new metaheuristic method that is inspired by the life cycle of water striders. This study attempts to enhance the performance of the WSA in order to improve solution accuracy, reliability, and convergence speed. The new method, called improved water strider algorithm (IWSA), is tested in benchmark mathematical functions and some structural optimization problems. In the proposed algorithm, the standard WSA is augmented by utilizing an opposition-based learning method for the initial population as well as a mutation technique borrowed from the genetic algorithm. By employing Generalized Space Transformation Search (GSTS) as an opposition-based learning method, more promising regions of the search space are explored; therefore, the precision of the results is enhanced. By adding a mutation to the WSA, the method is helped to escape from local optimums which is essential for engineering design problems as well as complex mathematical optimization problems. First, the viability of IWSA is demonstrated by optimizing benchmark mathematical functions, and then it is applied to three skeletal structures to investigate its efficiency in structural design problems. IWSA is compared to the standard WSA and some other state-of-the-art metaheuristic algorithms. The results show the competence and robustness of the IWSA as an optimization algorithm in mathematical functions as well as in the field of structural optimization.

Stroke Kinematics Analysis and Hydrodynamic Modeling of a Buoyancy-Supported Water Strider Robot

The locomotive ability of a water strider that generates an ellipse-like spatial stroke trajectory when moving is proved to improve its moving efficiency and is seldom imitated by water strider robots. A hydrodynamic analysis can predict the performance of the robots, but research in this area is not enough. A buoyancy-supported water strider robot with the ability of producing an ellipse-like spatial stroke trajectory was designed and analyzed in this study. A semiempirical hydrodynamic model suitable for the buoyancy-supported robot was proposed to study the hydrodynamic characteristics, based on the Newton’s second law of motion. The speed, power and efficiency of the robot were analyzed on the basis of the model which confirmed that the robot performing an ellipse-like spatial stroke trajectory was conducive to its moving efficiency. The experimental results verified that the stroke mechanism produced an ellipse-like spatial trajectory in a practical application and that the robot had good mobility. The proposed hydrodynamic model was validated by comparing the theoretical speed of the robot to the experimental results.

Experimental Study on Bearing Capacity of Water Striders on Water Surface

The paper developed a measuring device which can measure bearing capacity of water striders on the water surface, the measuring range is 1-10000μN, the precision is 0.1μN. The device includes micro force measurement and feed movement control system, electronic balance and control system can communicate with upper computer through RS232C serial. Through testing determination, the smallest linear feed speed of the device is 1 mm/min, which can satisfy the measurement requirements. The experiment measured the maximum bearing capacity of 5 samples of water striders on the water surface, which is 23.6 times its body weight.

The Microbiome of Neotropical Water Striders and Its Potential Role in Codiversification.

Simple SummaryInsects host a highly diverse bacterial community. Although we have a good understanding of the role that this microbiome plays in insects, the composition and diversity of microbiomes associated with Neotropical freshwater insects is virtually unknown. Here, we describe, for the first time, the microbiome associated with six species of Neotropical water striders in Panama. We also performed phylogenetic analyses to explore potential codiversification or coevolution between water strider species and their associated microbiome. We found a diverse microbiome associated with the six species of water striders, with the dominant bacterial taxa belonging to the phyla Proteobacteria and Tenericutes. Although some bacterial lineages were shared across species, some lineages were also uniquely associated with different water strider species. Our results suggest that both environmental variation and host phylogenetic identity are important drivers of the microbiome associated with water striders. Understanding the evolution of the host-microbiome interaction is crucial to our understanding of Neotropical freshwater ecosystems.Insects host a highly diverse microbiome, which plays a crucial role in insect life. However, the composition and diversity of microbiomes associated with Neotropical freshwater insects is virtually unknown. In addition, the extent to which diversification of this microbiome is associated with host phylogenetic divergence remains to be determined. Here, we present the first comprehensive analysis of bacterial communities associated with six closely related species of Neotropical water striders in Panama. We used comparative phylogenetic analyses to assess associations between dominant bacterial linages and phylogenetic divergence among species of water striders. We found a total of 806 16S rRNA amplicon sequence variants (ASVs), with dominant bacterial taxa belonging to the phyla Proteobacteria (76.87%) and Tenericutes (19.51%). Members of the α- (e.g., Wolbachia) and γ- (e.g., Acinetobacter, Serratia) Proteobacteria, and Mollicutes (e.g., Spiroplasma) were predominantly shared across species, suggesting the presence of a core microbiome in water striders. However, some bacterial lineages (e.g., Fructobacillus, Fluviicola and Chryseobacterium) were uniquely associated with different water strider species, likely representing a distinctive feature of each species’ microbiome. These findings indicate that both host identity and environmental context are important drivers of microbiome diversity in water striders. In addition, they suggest that diversification of the microbiome is associated with diversification in water striders. Although more research is needed to establish the evolutionary consequences of host-microbiome interaction in water striders, our findings support recent work highlighting the role of bacterial community host-microbiome codiversification.

Density-dependent sex-biased development of macroptery in a water strider.

In wing‐polymorphic insects, wing morphs differ not only in dispersal capability but also in life history traits because of trade‐offs between flight capability and reproduction. When the fitness benefits and costs of producing wings differ between males and females, sex‐specific trade‐offs can result in sex differences in the frequency of long‐winged individuals. Furthermore, the social environment during development affects sex differences in wing development, but few empirical tests of this phenomenon have been performed to date. Here, I used the wing‐dimorphic water strider Tenagogerris euphrosyne to test how rearing density and sex ratio affect the sex‐specific development of long‐winged dispersing morphs (i.e., sex‐specific macroptery). I also used a full‐sib, split‐family breeding design to assess genetic effects on density‐dependent, sex‐specific macroptery. I reared water strider nymphs at either high or low densities and measured their wing development. I found that long‐winged morphs developed more frequently in males than in females when individuals were reared in a high‐density environment. However, the frequency of long‐winged morphs was not biased according to sex when individuals were reared in a low‐density environment. In addition, full‐sib males and females showed similar macroptery incidence rates at low nymphal density, whereas the macroptery incidence rates differed between full‐sib males and females at high nymphal density. Thus complex gene‐by‐environment‐by‐sex interactions may explain the density‐specific levels of sex bias in macroptery, although this interpretation should be treated with some caution. Overall, my study provides empirical evidence for density‐specific, sex‐biased wing development. My findings suggest that social factors as well as abiotic factors can be important in determining sex‐biased wing development in insects.

Proposal of a Water-repellency Model of Water Strider and Its Verification by Considering Directly Measured Strider Leg-rowing Force

Proposal of a Water-repellency Model of Water Strider and Its Verification by Considering Directly Measured Strider Leg-rowing Force

A new species of Exochomoscirtes Pic, 1916 from Malaysia (Insecta: Coleoptera: Scirtidae) with biological notes on the bamboo-inhabiting members of the genus

Seven Exochomoscirtes species inhabiting phyto- or lithotelmata in West Malaysia and North Thailand were reared from larvae. E. hashimi spec. nov. from W. Malaysia was described and E. carinensis and E. meghalayensis were new records for Thailand. Larvae of E. meghalayensis inhabited water-filled tree holes and forest rock pools, while E. hajeki, E. jaechi, E. chiangmaiensis, E. carinensis, E. cf. luteosuturaloides and E. hashimi spec. nov. occurred in water-filled bamboo stems. Bamboo-inhabiting species occupied different types of bamboo habitats such as mature bamboo stems (inhabited internodes up to 21 m high), dead bamboo stems or bamboo stumps. Internodes of nutrient-rich bamboo shoots were not colonized. Adult Exochomoscirtes entered enclosed internode cavities through holes created by insects, woodpeckers and other animals or cracks in bamboo walls. Larvae living in open phytotelmata such as water-filled tree holes or bamboo stumps created pupal chambers made of soil or detritus in the vicinity of their habitats. In species inhabiting enclosed internodes pupal chambers were absent. Larvae pupated inside the internodes firmly attached to the bamboo walls close above water surface. Total development time of bamboo-inhabiting species was about 3 months. Predators of Exochomoscirtes species dwelling in enclosed internodes were chironomid larvae (Dasyhelea), mosquito larvae (Toxorhynchites), small water striders (Lathriovelia), rove beetles (Acylophorus), jumping spiders (Paracyrba), web-building spiders (Theridiidae) and web-building larvae of fungus gnats (Truplaya).
 
 Taxonomic acts
 E. hashimi spec. nov.– urn:lsid:zoobank.org:act:4D2AA5A6-DB2D-4B5F-AE91-E8C985FFA4DD