Microstructure of the biological attachment devices in the ladybugHarmonia axyridis(Coleoptera: Coccinellidae)

Abstract

Biological attachment device is optimized in insect legs for attachment onto the variety of natural substrate. We have studied the microstructural characteristics of the tarsal appendages in the ladybug Harmonia axyridis using scanning electron microscopy to reveal the attachment system of their legs. The attachment devices are composed of claws and adhesive pads. The claws are connected with pretarsal segment, and their apical diverged hooks are developed to hold rough substrates. In contrast, the adhesive pads have an adhesive function onto smooth surface. The pads are interspersed at the ventral part of each tarsomere, and are composed of two kinds of hairy setae. The discoid tip seta (DtS) has a spoon-shaped endplate usually with a rounded concave structure, whereas the pointed tip seta (PtS) has a pointed tip, usually with a hooked endplate. While the PtS is broadly localized concentrically on the marginal area of both the proximal and distal pads, the DtS can be seen at the central areas of each adhesive pad except for the hind legs. Our findings demonstrate the presence of the direction-dependence pattern of the fibrillar system as well as a functional modification of the tenent setae to achieve proper contact with almost any kind of substrates.

Porous substrate affects a subsequent attachment ability of the beetleHarmonia axyridis(Coleoptera, Coccinellidae)

“…Sexual dimorphism of adhesive pads in H. axyridis beetles (along with four other coccinellids studied) has been mentioned almost one decade before [32]. More recent study on the microstructure of attachment organs in this species, being very detailed and extensive, dealt with only male beetles, although did not indicate this fact [33]. Our results on the micromorphology of female and male adhesive pads are in line with the previously published data.…”

Microstructure of pretarsal pulvilli in shield bug Acanthosoma spinicolle (Heteroptera: Acanthosomatidae)

“…The hairy adhesive pads that increase the number of contact points with the surface by deformable setae occur in bugs (Edwards & Tarkanian ), beetles (Stork ; Moon et al . , ) and flies (Walker et al . ; Gorb ).…”

“…The hairy adhesive pads that increase the number of contact points with the surface by deformable setae occur in bugs (Edwards & Tarkanian 1970), beetles (Stork 1980;Moon et al 2012Moon et al , 2013 and flies (Walker et al 1985;Gorb 1998). However, smooth systems occurring as a soft deformable pad contact a smooth surface in aphids (Lees & Hardie 1988;Dixon et al 1990), grasshoppers (Jiao et al 2000) and ants (Federle et al 2002).…”