Vibrational Communication in Heelwalkers (Mantophasmatodea)

Abstract

Mantophasmatodea (Heelwalkers), described in 2002, is the most recently discovered insect order. Additionally, with only 21 species described to date, it is also among the smallest insect orders known. Mantophasmatodea are 1–4 cm long, secondarily wingless predators. They inhabit bushes, herbs, shrubs, or hide within grass tussocks in open semi-arid landscapes of sub-Saharan Africa. Adult males and females use percussive signals to communicate with one another, mainly for mate localization, recognition of male vs female, and potentially also for species recognition. Females drum their entire abdomen onto the substrate, producing single pulses spaced at regular intervals. Males use a special drumming organ located on their subgenital plate to generate groups of pulses (pulse trains), also repeated at regular intervals. Although most of the species investigated thus far occur in allopatry and have limited dispersal abilities, male vibrational signals are still surprisingly distinct from each other at an interspecific level, and most species can be distinguished by the structure of the male signal. Behavioral experiments additionally suggest that some information about species identity is encoded in male and female vibratory signals. However, the signals are probably mainly used for the localization of a potential mate within the structurally complex vegetation that the heelwalkers inhabit. Moreover, Mantophasmatodea possess very sensitive scolopidial organs to detect substrate vibrations—the well-developed subgenual organ complex within the tibia of all legs is probably most sensitive to the species-specific communication signals. Despite their recent discovery, comparatively little is known about their biology, behavior, and diversity.