How tight are beetle hugs? Attachment in mating leaf beetles

Abstract

Similar to other leaf beetles, rosemary beetles Chrysolina americana exhibit a distinct sexual dimorphism in tarsal attachment setae. Setal discoid terminals occur only in males, and they have been previously associated with a long-term attachment to the female's back (elytra) during copulation and mate guarding. For the first time, we studied living males and females holding to female's elytra. Pull-off force measurements with a custom-made tribometer featuring a self-aligning sample holder confirmed stronger attachment to female elytra compared with glass in both males and females; corresponding to 45 and 30 times the body weight, respectively. In line with previous studies, males generated significantly higher forces than females on convex elytra and flat glass, 1.2 times and 6.8 times, respectively. Convex substrates like elytra seem to improve the attachment ability of rosemary beetles, because they can hold more strongly due to favourable shear angles of legs, tarsi and adhesive setae. A self-aligning sample holder is found to be suitable for running force measurement tests with living biological samples.

Gripping ease in southern green stink bugsNezara viridulaL. (Heteroptera: Pentatomidae): Coping with geometry, orientation and surface wettability of substrate

“…1I). This is in accordance with previous reports on locusts (Vötsch et al 2002), ants (Federle et al 2002), flies ) and beetles (Voigt et al 2017b). Such a biphasic fluid mediates contact formation with a variety of surface chemistries, including hydrophobic plant cuticle and glass.…”

“…Voigt et al . , ), stink bugs neither exhibit a sexual tarsal dimorphism nor a sexually different attachment ability.…”

“…) and beetles (Voigt et al . ). Such a biphasic fluid mediates contact formation with a variety of surface chemistries, including hydrophobic plant cuticle and glass.…”

“…), leaf beetles (Coleoptera, Chrysomelidae; Voigt et al . ), honeybees (Hymenoptera, Apidae; Bräuer et al . ) and pentatomid bugs (Heteroptera, Pentatomidae; Voigt et al .…”

“…fixed plant leaves or artificial plates). However, convex surface structures have been recently experimentally demonstrated to promote attachment in scarabaeid beetles (Coleoptera, Scarabaeidae; Bußhardt et al 2014), longhorn beetles (Coleoptera, Cerambycidae; Voigt et al 2017a), leaf beetles (Coleoptera, Chrysomelidae;Voigt et al 2017b), honeybees (Hymenoptera, Apidae; Bräuer et al 2017) and pentatomid bugs (Heteroptera, Pentatomidae; Voigt et al 2018).…”