The predator defence system of an African king cricket (Orthoptera: Anostostomatidae): does it help to stink?
We examined the putative defence system of a king cricket, Onosandrus sp., in particular the efficacy of the noxious faeces against two types of predator: a lizard, the skink Mabuya striata (an active, diurnal forager), and the toad Bufo gutturalis (a nocturnal, ambush predator). Contrary to our predictions, the faeces did not act as a deterrent to either predator. Tongueflick trials with cotton scent applicators indicated that the skinks showed a heightened predatory response to king cricket faeces over king cricket integument, field cricket integument and an odourless control. We suggest that ‘primary’ defence mechanisms, such as nocturnal behaviour, cryptic colouration and immobility, are more effective than ‘secondary’ defence mechanisms, such as stridulation, kicking and defecation. Given that the noxious faeces already have a demonstrated role in inter- and intrasexual communication, we suggest that the assumed defensive role of the faeces is minor or an epiphenomenon.
Keywords: Anostostomatidae, king cricket, defence behaviour, tongue-flicks, predatory behaviour