Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

Prey capturing and feeding apparatus of dragonfly nymph

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey. Dragonfly nymphs are voracious predators that feed on smaller aquatic organisms. In this study, we examine dragonfly nymph (Libellulidae: Insecta: Odonata) mouthparts that are used in prey capturing and feeding. In particular, we characterise the morphology of the labium and mechanical properties of the mandibles of the nymph. Additionally, we record and analyse the preying mechanism using high-speed photography. The morphological details suggest that the prey capturing mechanism is a complex grasping mechanism with additional sensory organs that might aid in sensing the surroundings. The times taken for the extension and retraction of labial organ during prey capture was 187±54 ms. The Young’s modulus and hardness of the mandibles samples were 9.1±1.9 GPa and 0.85±0.13 GPa. Gradation in the mechanical properties was also observed in the mandible tip regions with increased properties at the tip end. The overall mechanism with its sensory capabilities provides a unique design to develop bioinspired underwater deployable mechanisms.

Environment friendly management of mosquito: a short review

Despite the large scale use of insecticides, capacity building, municipality, community and metropolis awareness, and preventive measures to counter vector borne diseases which are mounting day-by-day, new tools are now been introducing to prevent the spread of mosquito transmitted diseases. The low efficacy status of chemical pesticides have lead to the interest of researchers in search of fresh and even more practicable vector control methodologies to be applied. In this regards, multiple alternatives have been monitoring to develop control practice measures for the eradication, observation and control of mosquitoes at larval level by the use of a sustainable biological monitoring and control by an ordinary constructive predator, to exercise monitoring and practical control measures over parasites at larval stages in environmental and eco-friendly techniques. In particular, bio-control measures to monitor and control practical practices, context predatory larvivorous fish, dragonfly nymph, frogs, copepods, turtle, Entomopathogenic bacillus, Bacillus sphaericus and Bacillus thuringiensis israelensis are beings tried in different regions of world. The available research on the subject recommends that there exist multiple direct and indirect growth factors that could play a dynamic role in prey and predator’s survival. Species controphic that have an impact on concerned eco-relation reflect significant effect. In addition to this, certain eco-relations represent positive stimuli for the control of vector borne viral diseases. As a bio-control achieving feasible agent for vector monitoring, pointing, management and control predatory larvivorous fish, dragonfly nymph, frogs, copepods, turtle, Entomopathogenic bacillus, Bacillus sphaericus and Bacillus thuringiensis israelensis are not only considered as a liberated intervention for disease vector control of practices and mechanical control cost deterrents as well. Further research has been suggested on the subject so as to find out even more practicable and effective mosquito monitoring and practical control practices.Bangladesh J. Sci. Ind. Res.53(3), 169-178, 2018