Inter‐ and intraspecific differences in leaf beetle attachment on rigid and compliant substrates

Abstract

AbstractThe influence of substrate stiffness on the attachment ability of insects has been largely neglected so far. In the present study, traction experiments with adult beetles Gastrophysa viridula and Leptinotarsa decemlineata were carried out to study the influence of smooth, non‐structured surfaces, having different stiffness, on beetle attachment. Force measurements were performed with tethered walking adult insects, both males and females, intact and after removal of claws, on hydrophilic (normal) and hydrophobic (silanized) glass and four polydimethylsiloxane (PDMS) substrates ranging from 0.3 to 20 MPa in elastic modulus. Adult G. viridula generated higher safety factors (force/body weight) than L. decemlineata, 4.6–54.0 and 0.5–15.8 (min.–max.) respectively. The results show that the amputation of claws had no significant influence on the force generation by beetles on these smooth substrates. Males and females of both species performed best on stiffer surfaces having elastic moduli larger than 5 MPa. On the softer substrates, forces and safety factors significantly decreased. This effect was more prominent in L. decemlineata compared to the ten times lighter G. viridula. Since some natural substrates are rather soft, it is assumed that the effect of decrease in attachment ability of leaf beetles on soft substrata is of potential importance for the biology of leaf beetles.