A review: Learning from the flight of beetles

Morphological and structural characteristics of the elytra reduce impact damage to ladybird beetles

Beetle elytra act as natural protective covers and effectively shield their flexible abdomens and fragile hindwings from damage. The existing studies have attributed this contribution of the elytra to its honeycomb structures. In this combined experimental and theoretical study, we used the seven-spotted ladybird beetle to demonstrate that both biological morphology and the hollow structure of the dome-like elytra combined to reduce damage during falling. The falling ladybird beetles had a high probability (59.52%) of hitting the ground with the costal edge of the elytra. This strategy could assist with converting the translational energy into rotational kinetic energy, resulting in the reduction of the impulse during falling. In addition, the hollow structures on the elytra could further absorb the residual impact energy. In the future, this biological paradigm could be used as a basis for the development of falling/landing techniques for advanced robots.

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Crucial roles of specialized chitinases in elytral and hindwing cuticles construction in Leptinotarsa decemlineata

BACKGROUND

The Colorado potato beetle (CPB), Leptinotarsa decemlineata, is a major potato (Solanum tuberosum) pest, infesting over 16 million km2 and causing substantial economic losses. The insect cuticle forms an apical extracellular matrix (ECM) envelope covering exposed organs to direct morphogenesis and confer structural protection. While select chitinase (Cht) genes have proven essential for larval development, their potential activities directing ECM remodeling underlying adult wing maturation remain undefined.

RESULTS

We investigated the expression patterns and performed an oral RNA interference (RNAi) screen targeting 19 LdChts in late-instar L. decemlineata larvae. Subsequently, we assessed their effects on adult eclosion and wing characteristics. Knockdown of LdCht5, LdCht7, LdCht10, LdIDGF2, and LdIDGF4, as well as others from Group IV (LdCht15, LdCht12, LdCht17, and LdCht13) and Groups VII-X (LdCht2, LdCht11, LdCht1, and LdCht3), resulting in shrunken, misshapen elytra with reduced areal density, as well as transverse wrinkling and impaired wing-tip folding in hindwings. Scanning electron micrographs revealed eroded elytral ridges alongside thinned, ruptured hindwing veins, indicative of mechanical fragility post-LdCht suppression. Spectroscopic analysis uncovered biomolecular alterations underlying the elytral anomalies, including decreases in peaks representing chitin, proteins, and lipids. This loss of essential ECM components provides evidence for the fragility, wrinkling, and shrinkage observed in the RNAi groups.

CONCLUSION

Our findings elucidate the crucial role of chitinases in the turnover of chitinous cuticles on beetle wings, offering insights into RNAi-based control strategies against this invasive pest. © 2024 Society of Chemical Industry.

Spatial variation in the recovery potential of freshwater macroinvertebrate assemblages: Moving towards spatially defined assemblage vulnerability to chemicals

The vulnerability of freshwater biodiversity to chemical stressors is dependent on its ability to resist chemical stress and recover from any stress-induced effects. Spatial variation in recovery has the potential to exacerbate or mitigate assemblage vulnerability but this has not been explored in detail. By combining information on assemblage-specific recovery potential with information on assemblage-specific chemical sensitivity, we have demonstrated that the vulnerability of 3307 macroinvertebrate assemblages to 18 different chemicals is spatially dependent and that recovery potential may reduce chemical risk. The recovery potential of each assemblage was quantified based on trait information and landscape factors using a weighted sum method, but it did not consider succession processes. Recovery potential varied by river type with assemblages in mid-altitude siliceous rivers with small catchments in the west of England having the lowest recovery potential. For 17 or the 18 chemicals investigated, there was a positive correlation between the recovery potential and sensitivity and this was strongest for assemblages exposed to metals. More sensitive assemblages had a higher recovery potential and were therefore potentially less vulnerable than would be expected based on sensitivity alone. Assemblages in rivers with small catchments were the most vulnerable to chemical exposure. Furthermore, assemblages with high vulnerability to insecticide exposure were more prevalent in mid-altitude rivers with siliceous geology in the west of England, whereas assemblages with high vulnerability to metals were more prevalent in lowland rivers with calcareous or mixed geology in the midlands. This study: (i) highlights the importance of spatial context in determining the risk of chemical pollution to freshwater biodiversity; (ii) demonstrates how spatial variation in taxonomic composition influences both the internal and external recovery of assemblages and how landscape factors modify trait-based recovery capabilities; (iii) provides the foundations for spatially-defined vulnerability assessment by identifying ecological scenarios for assessing chemical risk.

Effect of α-cypermethrin and pirimiphos-methyl on wing morphology of Tribolium castaneum (Herbst) and T. confusum Jacquelin du Val: a comparative study

Tribolium castaneum (Herbst) and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) are widespread and serious pests of stored products. Various insecticides are applied aiming to effectively manage both species. Here, two insecticides are tested, the pyrethroid α-cypermethrin and the organophosphate pirimiphos-methyl, hypothesizing that they can lead to morphological changes in the certain body parts of the adult offspring of treated T. castaneum and T. confusum parental female adults. For this purpose, the geometric morphometric method to the elytra and hindwings was applied. Both males and females were included in the analysis. The results showed that adult individuals of T. confusum showed higher tolerance to both insecticides compared to T. castaneum adults. This finding is reflected in analyses of both pairs of wings in T. confusum where changes in shape were negligible. The hindwings of T. castaneum experienced deformations to both insecticides. More significant changes in wing shape were observed in the α-cypermethrin treatment compared to pirimiphos-methyl. In the case of T. castaneum, even the shortest exposure to insecticides (5 min) is enough to provoke shape changes in the hindwings. Deformities in offspring, caused after treatment of their parents with insecticides, could moderate the frequency of insecticidal applications in storages.

Detection of Hindwing Landmarks Using Transfer Learning and High-Resolution Networks

Hindwing venation is one of the most important morphological features for the functional and evolutionary analysis of beetles, as it is one of the key features used for the analysis of beetle flight performance and the design of beetle-like flapping wing micro aerial vehicles. However, manual landmark annotation for hindwing morphological analysis is a time-consuming process hindering the development of wing morphology research. In this paper, we present a novel approach for the detection of landmarks on the hindwings of leaf beetles (Coleoptera, Chrysomelidae) using a limited number of samples. The proposed method entails the transfer of a pre-existing model, trained on a large natural image dataset, to the specific domain of leaf beetle hindwings. This is achieved by using a deep high-resolution network as the backbone. The low-stage network parameters are frozen, while the high-stage parameters are re-trained to construct a leaf beetle hindwing landmark detection model. A leaf beetle hindwing landmark dataset was constructed, and the network was trained on varying numbers of randomly selected hindwing samples. The results demonstrate that the average detection normalized mean error for specific landmarks of leaf beetle hindwings (100 samples) remains below 0.02 and only reached 0.045 when using a mere three samples for training. Comparative analyses reveal that the proposed approach out-performs a prevalently used method (i.e., a deep residual network). This study showcases the practicability of employing natural images-specifically, those in ImageNet-for the purpose of pre-training leaf beetle hindwing landmark detection models in particular, providing a promising approach for insect wing venation digitization.

Bio-inspired flapping wing robots with foldable or deformable wings: a review

Traditional flapping-wing robots (FWRs) obtain lift and thrust by relying on the passive deformation of their wings which cannot actively fold or deform. In contrast, flying creatures such as birds, bats, and insects can maneuver agilely through active folding or deforming their wings. Researchers have developed many bio-inspired foldable or deformable wings (FDWs) imitating the wings of flying creatures. The foldable wings refer to the wings like the creatures' wings that can fold in an orderly manner close to their bodies. Such wings have scattered feathers or distinct creases that can be stacked and folded to reduce the body envelope, which in nature is beneficial for these animals to prevent wing damage and ensure agility in crossing bushes. The deformable wings refer to the active deformation of the wings using active driving mechanisms and the passive deformation under the aerodynamic force, which functionally imitates the excellent hydrodynamic performance of the deformable body and wings of the creatures. However, the shape and external profile changes of deformable wings tend to be much smaller than that of folding wings. FDWs enable the FWRs to improve flight degree of flexibility, maneuverability, and efficiency and reduce flight energy consumption. However, FDWs still need to be studied, and a comprehensive review of the state-of-the-art progress of FDWs in FWR design is lacking. This paper analyzes the wing folding and deformation mechanisms of the creatures and reviews the latest progress of FWRs with FDWs. Furthermore, we summarize the current limitations and propose future directions in FDW design, which could help researchers to develop better FWRs for safe maneuvering in obstacle-dense environments.

Design optimization and wind tunnel investigation of a flapping system based on the flapping wing trajectories of a beetle's hindwings

To design a flapping-wing micro air vehicle (FWMAV), the hovering flight action of a beetle species (Protaetia brevitarsis) was captured, and various parameters, such as the hindwing flapping frequency, flapping amplitude, angle of attack, rotation angle, and stroke plane angle, were obtained. The wing tip trajectories of the hindwings were recorded and analyzed, and the flapping kinematics were assessed. Based on the wing tip trajectory functions, bioinspired wings and a linkage mechanism flapping system were designed. The critical parameters for the aerodynamic characteristics were investigated and optimized by means of wind tunnel tests, and the artificial flapping system with the best wing parameters was compared with the natural beetle. This work provides insight into how natural flyers execute flight by experimentally duplicating beetle hindwing kinematics and paves the way for the future development of beetle-mimicking FWMAVs.

Electrochemical Performance of Thick-Film Li(Ni0.6Mn0.2Co0.2)O2 Cathode with Hierarchic Structures and Laser Ablation

The electrochemical performance of lithium-ion batteries is directly influenced by type of active material as well as its morphology. In order to evaluate the impact of particle morphology in thick-film electrodes, Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) cathodes with bilayer structure consisting of two different particle sizes were manufactured and electrochemically characterized in coin cells design. The hierarchical thick-film electrodes were generated by multiple casting using NMC 622 (TA) with small particle size of 6.7 µm and NMC 622 (BA) with large particle size of 12.8 µm. Besides, reference electrodes with one type of active material as well as with two type of materials established during mixing process (BT) were manufactured. The total film thickness of all hierarchical composite electrodes were kept constant at 150 µm, while the thicknesses of TA and BA were set at 1:2, 1:1, and 2:1. Meanwhile, three kinds of thin-film cathodes with 70 µm were applied to represent the state-of-the-art approach. Subsequently, ultrafast laser ablation was applied to generate groove structures inside the electrodes. The results demonstrate that cells with thin-film or thick-film cathode only containing TA, cells with bilayer electrode containing TBA 1:2, and cells with laser-structured electrodes show higher capacity at C/2 to 5C, respectively.