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Anatomy of the honeybee’s stinger apparatus. The stinger resides in the sting chamber inside the last abdominal segment (not to scale). The sting apparatus mainly comprises the protractor/retractor muscles, the bulb, the stinger, and the venom sac. The protractor muscles drive the stinger to penetrate the wound and the retractor muscles are used in the reverse manner to pull the stinger back into the sting chamber. During penetration, the venom is pumped into the stinger from the bulb, which is also known as the venom reservoir. doi:10.1371/journal.pone.0103823.g001 

Anatomy of the honeybee’s stinger apparatus. The stinger resides in the sting chamber inside the last abdominal segment (not to scale). The sting apparatus mainly comprises the protractor/retractor muscles, the bulb, the stinger, and the venom sac. The protractor muscles drive the stinger to penetrate the wound and the retractor muscles are used in the reverse manner to pull the stinger back into the sting chamber. During penetration, the venom is pumped into the stinger from the bulb, which is also known as the venom reservoir. doi:10.1371/journal.pone.0103823.g001 

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The stinger is a very small and efficient device that allows honeybees to perform two main physiological activities: repelling enemies and laying eggs for reproduction. In this study, we explored the specific characteristics of stinger penetration, where we focused on its movements and the effects of it microstructure. The stingers of Italian honey...

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... variable and complex environments, animals are equipped with different organs for accomplishing diverse physical activities. Stingers and needles are found in some insects in the orders Diptera and Hymenoptera, where they play important roles in predation, mating, and defense [1–5]. Various theories have been developed to describe the penetration mechanism of insect stingers and needles [6–9]. A comprehensive understanding of stinger penetration has been obtained gradually, which has attracted the interest of the developers of bio-inspired instruments, e.g., painless insertion for medical care [10] and bionic-based drilling technol- ogies for planetary subsurface exploration [11]. The abdomen of the honeybee ( Apis mellifera ) comprises 10 segments, seven of which are obvious [12–14]. The cavity within the last abdominal segment of the honeybee is called the sting chamber and the entire sting apparatus is enclosed within the chamber when it is not in use, as well as nerve ganglions, various muscles, a venom sac, and the end of the insect’s digestive tract [15–16]. The stinger is a small and delicate device, which allows honeybee workers to defend their nest against predators [12]. As shown in Fig. 1, when dangerous enemies are encountered, the sting apparatus receives a signal from the nerve ganglions and the bee bends its abdomen downward due to muscle contractions as it prepares for vertical stinger penetration. During the use of the stinger, two pairs of protractor and retractor muscles move the stinger up and down, which causes a flexible extension of the stinger shaft. Movements of the bee’s legs, the muscles of the abdomen, and the effect of the backward pointing barbs combine to produce a thrust that drives the stinger efficiently, and the venom is delivered instantly into tough skin through a channel in the stinger. The first analysis of the stinger penetration mechanism was performed by Dade in 1890s, particularly the coordination between various organs [14]. The stinger comprises two lancets with groups of curved barbs on the outer aspects of their distal ends, which are held in grooves on the stylet [14]. It is well known that the main role of the barb is to provide one-way traction, which allows the stinger to work itself deeper into the flesh [13,14]. The raked structure of the barbs makes it difficult to remove the sting, which might help the bee to continue pumping venom into the flesh via the detached stinger for a relatively long time [14]. In this case, the underlying mechanism of penetration appears relatively simple, i.e., the needle-like stinger is assumed to move axially while piercing the skin, but the possible role of rotation along the stinger shaft has been neglected. This is because the bee stingers measure a few millimeters and the action of stinging occurs within one second, thus the actual penetration behavior cannot be observed easily. Previous research has only considered the morphology at the level of a single barb. However, the potential effects of the distribution of the barbs on the efficiency of penetration have not been identified clearly. In this study, we explored the penetration mechanism of the honeybee stinger. We investigated the morphology of the barbs on the bee stinger and elucidated the specific factors that determine the rotation of the stinger. Our results showed that the stinger undergoes helical and clockwise rotation during penetration, where the spiral distribution of the barbs is responsible for this phenomenon. We studied the penetration characteristics of the stingers of honeybee ( Apis mellifera ligustica ) workers. The samples were collected at Tsinghua University of Beijing, China (40.000153 u N, 116.326414 E). No specific permissions were required for these locations/activities. We confirm that the field studies did not involve endangered or protected species. To ensure the reliability and repeatability of the experiments, all of the honeybee samples were captured around wild bee nests and the experiments were conducted within 1 h of collection. In total, 30 fresh stingers from worker bees were selected, cleaned, and dehydrated, where the average length was 8.5 mm (Fig. 2). We performed two types of experiments to elucidate the stinging mechanism. As shown in Fig. 1, we first separated the stingers into two groups, where group I and group II contained 20 and 10 stinger samples, respectively. The 20 stingers in group I were then grouped into subgroups A 1 , A 2 , A 3 , and A 4 , each of which comprised five samples. Four types of 10 6 10 6 10 mm cubic substrates were prepared, which were made of agar, silica gel, soft rubber, and paraffin wax. The samples in Groups A 1 , A 4 were fixed to the 20% Poly Vinyl Alcohol (PVA) colloid droplets which were firstly dispensed on the PMMA panel. Thereby tips of the stings were placed onto the substrate of the cubic block of different materials (See Figure S3 in File S1). All of the stings were pressed for 6.0 mm into the substrate with a precision position platform with the average velocity approximately to 6 mm/s (Fig. 2). In addition, to eliminate any errors caused by the setup, we tested rotation angles of the human hair samples that measured ca 8.5 mm in length for comparison. Morphological images of cross- sections of the stingers and hairs were obtained before and after penetration by microscopy. Notably we observed the natural heads of the stingers directly to determine whether the helical penetration exists or not [17]. With the help of the environmental scanning electron microscope (ESEM), we observed the microstructure of 10 stingers in group I. Fig. 3 shows the method used to observe the stinger cross- sections and to calculate the rotation angles. The cross-sections of the stinger were observed and photographed before and after penetration. We enhanced the microscope so it could locate the cubic substrates by using a positioning block, thereby ensuring that the cubic substrate remained fixed. The rotation angles were measured by comparing the positions of markers in the stinger cross-sections. The image processing system used to capture the contours of the cross-sections of the stingers was implemented with the Canny operator. We define the equation of the contours as F ( x , y ) ~ 0 ...
Context 2
... variable and complex environments, animals are equipped with different organs for accomplishing diverse physical activities. Stingers and needles are found in some insects in the orders Diptera and Hymenoptera, where they play important roles in predation, mating, and defense [1–5]. Various theories have been developed to describe the penetration mechanism of insect stingers and needles [6–9]. A comprehensive understanding of stinger penetration has been obtained gradually, which has attracted the interest of the developers of bio-inspired instruments, e.g., painless insertion for medical care [10] and bionic-based drilling technol- ogies for planetary subsurface exploration [11]. The abdomen of the honeybee ( Apis mellifera ) comprises 10 segments, seven of which are obvious [12–14]. The cavity within the last abdominal segment of the honeybee is called the sting chamber and the entire sting apparatus is enclosed within the chamber when it is not in use, as well as nerve ganglions, various muscles, a venom sac, and the end of the insect’s digestive tract [15–16]. The stinger is a small and delicate device, which allows honeybee workers to defend their nest against predators [12]. As shown in Fig. 1, when dangerous enemies are encountered, the sting apparatus receives a signal from the nerve ganglions and the bee bends its abdomen downward due to muscle contractions as it prepares for vertical stinger penetration. During the use of the stinger, two pairs of protractor and retractor muscles move the stinger up and down, which causes a flexible extension of the stinger shaft. Movements of the bee’s legs, the muscles of the abdomen, and the effect of the backward pointing barbs combine to produce a thrust that drives the stinger efficiently, and the venom is delivered instantly into tough skin through a channel in the stinger. The first analysis of the stinger penetration mechanism was performed by Dade in 1890s, particularly the coordination between various organs [14]. The stinger comprises two lancets with groups of curved barbs on the outer aspects of their distal ends, which are held in grooves on the stylet [14]. It is well known that the main role of the barb is to provide one-way traction, which allows the stinger to work itself deeper into the flesh [13,14]. The raked structure of the barbs makes it difficult to remove the sting, which might help the bee to continue pumping venom into the flesh via the detached stinger for a relatively long time [14]. In this case, the underlying mechanism of penetration appears relatively simple, i.e., the needle-like stinger is assumed to move axially while piercing the skin, but the possible role of rotation along the stinger shaft has been neglected. This is because the bee stingers measure a few millimeters and the action of stinging occurs within one second, thus the actual penetration behavior cannot be observed easily. Previous research has only considered the morphology at the level of a single barb. However, the potential effects of the distribution of the barbs on the efficiency of penetration have not been identified clearly. In this study, we explored the penetration mechanism of the honeybee stinger. We investigated the morphology of the barbs on the bee stinger and elucidated the specific factors that determine the rotation of the stinger. Our results showed that the stinger undergoes helical and clockwise rotation during penetration, where the spiral distribution of the barbs is responsible for this phenomenon. We studied the penetration characteristics of the stingers of honeybee ( Apis mellifera ligustica ) workers. The samples were collected at Tsinghua University of Beijing, China (40.000153 u N, 116.326414 E). No specific permissions were required for these locations/activities. We confirm that the field studies did not involve endangered or protected species. To ensure the reliability and repeatability of the experiments, all of the honeybee samples were captured around wild bee nests and the experiments were conducted within 1 h of collection. In total, 30 fresh stingers from worker bees were selected, cleaned, and dehydrated, where the average length was 8.5 mm (Fig. 2). We performed two types of experiments to elucidate the stinging mechanism. As shown in Fig. 1, we first separated the stingers into two groups, where group I and group II contained 20 and 10 stinger samples, respectively. The 20 stingers in group I were then grouped into subgroups A 1 , A 2 , A 3 , and A 4 , each of which comprised five samples. Four types of 10 6 10 6 10 mm cubic substrates were prepared, which were made of agar, silica gel, soft rubber, and paraffin wax. The samples in Groups A 1 , A 4 were fixed to the 20% Poly Vinyl Alcohol (PVA) colloid droplets which were firstly dispensed on the PMMA panel. Thereby tips of the stings were placed onto the substrate of the cubic block of different materials (See Figure S3 in File S1). All of the stings were pressed for 6.0 mm into the substrate with a precision position platform with the average velocity approximately to 6 mm/s (Fig. 2). In addition, to eliminate any errors caused by the setup, we tested rotation angles of the human hair samples that measured ca 8.5 mm in length for comparison. Morphological images of cross- sections of the stingers and hairs were obtained before and after penetration by microscopy. Notably we observed the natural heads of the stingers directly to determine whether the helical penetration exists or not [17]. With the help of the environmental scanning electron microscope (ESEM), we observed the microstructure of 10 stingers in group I. Fig. 3 shows the method used to observe the stinger cross- sections and to calculate the rotation angles. The cross-sections of the stinger were observed and photographed before and after penetration. We enhanced the microscope so it could locate the cubic substrates by using a positioning block, thereby ensuring that the cubic substrate remained fixed. The rotation angles were measured by comparing the positions of markers in the stinger cross-sections. The image processing system used to capture the contours of the cross-sections of the stingers was implemented with the Canny operator. We define the equation of the contours as F ( x , y ) ~ 0 ...

Citations

... Especially, the drilling principle whereby the mouthpart structure performs rotating and torsions movements to open the skin is one of the basic principles of piercing mechanisms that can be distinguished [33]. The honeybees have stinger shaft which is found to rotate when inserting into tissues, and this helical penetration facilities a straight and easier insertion [34]. Such cyclic motion can reduce the deformation and strain on the surrounding substrate, which inspires the control of microneedles with cyclic rotation, with a likely reduction in damage along the needle insertion track. ...
Article
Full-text available
Microneedle permits transdermal biosensing and drug delivery with minor pain. However, accurate microneedle transdermal positioning with minimal skin deformation remains a significant technical challenge due to inhomogeneous skin topology and discontinuous force applied to the microneedle. Here, we introduce bioinspired rotation microneedles for in vivo accurate microneedle positioning as inspired by honeybees’ stingers. We demonstrate the benefits of rotation microneedles in alleviating skin resistance through finite element analysis, full-thickness porcine validations, and mathematical derivations of microneedle-skin interaction stress fields. The max penetration force was mitigated by up to 45.7% and the force attenuation rate increased to 2.73 times in the holding stage after penetration. A decrease in max skin deflection and a faster deformation recovery introduced by rotation microneedles implied a more precise penetration depth. Furthermore, we applied the rotation microneedles in psoriasis mice, a monogenic disorder animal model, for minimally invasive biological sample extraction and proinflammatory cytokine monitoring. An ultrasensitive detection method is realized by using only one microneedle to achieve cytokine mRNA level determination compared to commonly required biopsies or blood collection. Thus, rotation microneedles permit a simple, rapid, and ultraminimal-invasive method for subcutaneous trace biological sample acquisition and subsequent point-of-care diagnostics with minimal damage to both microneedles and skins.
... A nonlinear finite element method (FEM) [16] showed that the stress concentrations were around the stinger tip and its barbs during the insertion process, while the barbs were jammed in and torn the skin during the pull process. Wu et al [17] observed the process of honeybee stingers penetrate into four different substrates, then the morphological characteristics of the stinger crosssections were analyzed before and after penetration by microscopy. Zhao et al [18] exhibited the process of honeybees inserting stingers into silicon substrate with a high-speed camera. ...
Article
Full-text available
To investigate the microstructure-property relations of honeybee stingers, the cross-section microstructures were analyzed by scanning electron microscope (SEM) and the mechanical properties of honeybee stingers were tested by nanoindentation experiment in vivo in this paper. The Young’s modulus and hardness in the cross section of different segments of honeybee stingers were obtained. It is found that the honeybee stinger is of a hierarchical structure in cross section, which varies from the root to the tip and leads to quite different mechanical properties of the stingers. The natural optimized microstructure and excellent mechanical properties of the stingers effectively contribute to the biological function and self-protection performance of honeybees.
... Many research efforts to mimic insect stingers are ongoing with penetration mechanisms such as honeybee [17][18][19] and mosquito [20] to help facilitate better needle insertion. Insect stingers hold promise for modernizing needle design, as the stingers have evolved and become adept at entering human tissue through various mechanical and dynamic insertion techniques [21]. ...
Article
Full-text available
The design of surgical needles used in biopsy procedures have remained fairly standard despite the increase in complexity of surgeries. Higher needle insertion forces and deflection can increase tissue damage and decrease biopsy sample integrity. To overcome these drawbacks, we present a novel bioinspired approach to reduce insertion forces and minimize needle-tip deflection. It is well known from the literature, design of bioinspired surgical needles results in decreasing insertion forces and needle-tip deflection from the needle insertion path. This technical note studies the influence of vibration on bioinspired needle to further reduce insertion forces and needle-tip deflection. Bioinspired needle geometrical parameters such as barb shapes and geometries were analyzed to determine the best design parameters. Static and dynamic (vibration) needle insertion tests were performed to determine the maximum insertion forces and to estimate needle-tip deflection. Our results show that introducing vibration on the bioinspired needle insertion can reduce the maximum insertion force by up to 50%. It was also found that the needle-tip deflection is decreased by 47%.
... They are covered by tetrahedron-shaped barbs, which are distributed in a spiral right-handed manner. This specific type of distribution plays a fundamental role in the helically clockwise rotation of the sting during the penetration of the stinger into the wound and reduces the penetration force (35). These barbs make it almost impossible for the bee to retract its stinger from the elastic flesh of mammals when escaping ( Figure 2B). ...
Article
Full-text available
Honey bees can be found all around the world and fulfill key pollination roles within their natural ecosystems, as well as in agriculture. Most species are typically docile, and most interactions between humans and bees are unproblematic, despite their ability to inject a complex venom into their victims as a defensive mechanism. Nevertheless, incidences of bee stings have been on the rise since the accidental release of Africanized bees to Brazil in 1956 and their subsequent spread across the Americas. These bee hybrids are more aggressive and are prone to attack, presenting a significant healthcare burden to the countries they have colonized. To date, treatment of such stings typically focuses on controlling potential allergic reactions, as no specific antivenoms against bee venom currently exist. Researchers have investigated the possibility of developing bee antivenoms, but this has been complicated by the very low immunogenicity of the key bee toxins, which fail to induce a strong antibody response in the immunized animals. However, with current cutting-edge technologies, such as phage display, alongside the rise of monoclonal antibody therapeutics, the development of a recombinant bee antivenom is achievable, and promising results towards this goal have been reported in recent years. Here, current knowledge on the venom biology of Africanized bees and current treatment options against bee envenoming are reviewed. Additionally, recent developments within next-generation bee antivenoms are presented and discussed.
... Structure, geometry, nanomechanical properties, and insertion mechanics of stingers of various species have been studied (Politi et al. 2012;Wu et al. 2014;Zhao et al. 2015Zhao et al. , 2018Das et al. 2018). ...
Article
Full-text available
This paper provides an overview of lessons from mosquitoes’ locomotion and their painless piercing and from wasp stinging. Based on the understanding, conceptual schematics of bioinspired microneedle designs are presented for biomedical applications. In the first part, mosquitoes locomotory attributes, which are used by them to hunt a host, are described. Next, microanatomy, feeding process, and nanomechanical properties data of mosquitoes’ labrum are presented. A hypothesis behind the painless piercing is presented followed by mosquito-inspired microneedle design guidelines. In the second part, wasp anatomy and stinging process are described. Their structure and nanomechanical properties data, modeling of the penetration process, and stinger-inspired microneedle design guidelines are presented.
... In some cases, such as bee stingers or porcupine quills, spines are anchored into the target and left behind when the organism disengages. The spines of these taxa usually have ornamentation that helps to both puncture and anchor the spines in the tissue of the offending predator [6,11,12]. In plants, spines can serve to deter herbivory, but often have alternative functions as well [13][14][15][16][17][18]. ...
Article
Full-text available
Spines are common morphological features found in almost all major biological groups offering an opportunity to explore large-scale evolutionary convergence across disparate clades. As an example, opuntioid cacti have spines with barbed ornamentation that is remarkably similar in form and scale to that found on porcupine quills, suggesting specific biomechanical convergence across the animal and plant kingdoms. While the mechanics of porcupine quills as defensive mechanisms has been previously tested, the mechanics of cactus spines (which have evolved to fill a number of functions including defence, climbing and dispersal) has not been characterized. Here we study the puncturing and anchoring ability of six species of cactus, including both barbed and non-barbed spines. We found that barbed spines require less work to puncture a variety of targets than non-barbed spines. Barbed spines also require more work than non-barbed spines to withdraw from biological materials, owing to their barbs engaging with tissue fibres. These results closely match those found previously for barbed versus non-barbed porcupine quills, implying biomechanical convergence. The variation in performance of barbed versus non-barbed spines, as well as between barbed spines from different species, is probably tied to the diversity of ecological functions of cactus spines.
... Experimental studies have shown that sharpened ridges on biological tools allow for more efficient puncture than tools lacking such ridges (Freeman and Lemen, 2006;Cho et al., 2012). Recent work has identified helically oriented barbs on honey bee stingers that aid in puncture when coupled with a rotating motion during insertion (Wu et al., 2014). Work on porcupine spines and hymenopteran stingers has shown that barbs can act as stress concentrators during insertion (Cho et al., 2012;Zhao et al., 2015). ...
Article
A viper injecting venom into a target, a mantis shrimp harpooning a fish, a cactus dispersing itself via spines attaching to passing mammals; all these are examples of biological puncture. Although disparate in terms of materials, kinematics and phylogeny, all three examples must adhere to the same set of fundamental physical laws that govern puncture mechanics. The diversity of biological puncture systems is a good case study for how physical laws can be used as a baseline for comparing disparate biological systems. In this Review, I explore the diversity of biological puncture and identify key variables that influence these systems. First, I explore recent work on biological puncture in a diversity of organisms, based on their hypothesized objectives: gripping, injection, damage and defence. Variation within each category is discussed, such as the differences between gripping for prey capture, gripping for dispersal of materials or gripping during reproduction. The second half of the Review is focused on specific physical parameters that influence puncture mechanics, such as material properties, stress, energy, speed and the medium within which puncture occurs. I focus on how these parameters have been examined in biology, and how they influence the evolution of biological systems. The ultimate objective of this Review is to outline an initial framework for examining the mechanics and evolution of puncture systems across biology. This framework will not only allow for broad biological comparisons, but also create a baseline for bioinspired design of both tools that puncture efficiently and materials that can resist puncture.
... Like the wasp stinger, the honeybee also regulates its penetration angle from −6° to −13° at the different stages of penetration 1 and follows the similar mechanism. The only difference is that the reverse facing barbs of the honeybee stinger allow the honeybee stinger to puncture the human skin or any object by a lesser amount of insertion force 3,16 . The average penetration angle of the honeybee stinger is reported as −8.3° 10 . ...
Article
Full-text available
In order to design a painless and mechanically durable micro syringe-needle system for biomedical applications, the study of insect stingers is of interest because of their elegant structures and functionalities. In the present work, the structure, mechanical properties and the mechanical behavior during insertion of wasp and honeybee stingers have been investigated. The non-invasive imaging tool, micro-computed tomography has been employed to reveal the 3D-structures of wasp and honeybee stingers. A quasi-static nanoindentation instrument was used to measure the nanomechanical properties. Both wasp and honeybee stingers have graded mechanical properties, decreasing along their longitudinal direction starting from the base. The computed tomography images and the measured material properties from nanoindentation were fed into a computational framework to determine the mechanical behavior of the stingers during penetration. The computation results predicted the penetration angle of +10o for the wasp stinger and -6o for the honeybee stinger, which mimics the practical insertion mechanism of both stingers. Based on this understanding, a wasp and honeybee stringer inspired micro syringe-needle design has also been proposed.
... Shing and Erickson (1982) have determined that such sensillum is associated with each of the barbs except those distal. Dade (1994) and Wu et al (2014) stated that the main role of these barbs is to provide one-way traction of the sting that makes it penetrate deeper into the flesh. This might help the bee to continue pumping the venom into the victim for a relatively long time after separation of the sting (Dade, 1994). ...
... Our results showed that there are 10 acute barbs on each lancet. Our observations were similar to those of Wu et al (2014) who mentioned that there are two rows of barbs on the stinger of Apis mellifera ligustica each of which comprises about 10 acute barbs. However this number may vary according to the species. ...
... Some researchers have investigated honeybee stingers. For example, Ling et al [36] and Wu et al [37] separately studied the mechanics of the honeybee stinger and its barbs. Ling et al [36] concluded that the geometry of the stinger provides a relatively painless penetration into the human skin. ...
... The extraction force was increased due to the mechanical interlocking of the barbs in the tissue. Wu [37] discussed the insertion mechanics of the honeybee stinger, and concluded that barbs in the stinger reduce the insertion force and also cause the stinger to rotate as it enters human skin. ...
Article
The focus of this paper is to present new designs of innovative bioinspired needles to be used during percutaneous procedures. Insect stingers have been known to easily penetrate soft tissues. Bioinspired needles mimicking the barbs in a honeybee stinger were developed for a smaller insertion force, which can provide a less invasive procedure. Decreasing the insertion force will decrease the tissue deformation, which is essential for a more accurate targeting. In this study, some design parameters, in particular, barb shape and geometry (i.e., front angle, back angle, and height) were defined and their effects on the insertion force were investigated. Three-dimensional (3D) printing technology was used to manufacture bioinspired needles. A specially-designed insertion test setup using tissue mimicking Polyvinyl chloride (PVC) gels was developed to measure the insertion and extraction forces. The barb design parameters were then experimentally modified through detailed experimental procedures to further reduce the insertion force. Different scales of the barbed needles were designed and used to explore the size-scale effect on the insertion force. To further investigate the efficacy of the proposed needle design in real surgeries, preliminary ex-vivo insertion tests into bovine liver tissue were performed. Our results show that the insertion force of the needles in different scales decreased by 21-35% in PVC gel insertion tests and by 46% in bovine liver tissue insertion tests.