Attachment forces of the hemelytra-locking mechanisms in aquatic bugs (Heteroptera: Belostomatidae)

Combined hemelytra-locking system of Heteroptera, consisting of several locking mechanisms, aids the mechanical stabilisation of the body at rest, resists external loads, and keeps air stored with the option to easily unlock hemelytra prior to flight. The resistance to unlocking of the hemelytron was measured (in mN) with the aid of a load cell force transducer combined with a three-axial micromanipulator. It is shown that macro- and microstructural features of several submechanisms are responsible for their directionality. The highest resistance to unlocking was measured in lateral and dorsal directions. Summarised force of separately measured submechanisms was considerably lower than the force measured in the combined mechanism. Each submechanism is optimised for achieving high resistance to the hemelytron uncoupling in particular direction(s) and to be easily unlocked in another direction. It was demonstrated in the high-speed videorecordings that hemelytra uncoupling is promoted by their short anterior displacement.