The role of intraspecific mechanical and chemical signaling for mate and sexual recognition in male Tityus pusillus (Scorpiones, Buthidae)

Abstract

Hydrophobic compounds present in the cuticular wax layer (CWL) of terrestrial arthropods protect them from dehydration and are also involved in chemical communication. However, the role of CWL compounds in the behavioral ecology of scorpions has been studied less often, with most investigations focusing on their responses to mechanical stimuli. In this study, we aimed to characterize the CWL composition of Tityus pusillus (Scorpiones, Buthidae) and examine the influence of CWL solvent extracts and movement on intraspecific mate and sexual recognition by males of this species. We analyzed CWL hexane extracts of adult female and male T. pusillus by gas chromatography-mass spectrometry (GC-MS). In paired behavioral tests inside an experimental arena, we exposed adult males to i) live and intact dead conspecific females; ii) intact dead females and females without the CWL (removed with solvent washes); and iii) intact dead males with and without the CWL. Our results showed that CWL extracts of both female and male T. pusillus contained a series of linear alkanes (C21 - C34; > 54 % relative composition), as well as fatty acyls (> 9.5 %) and methyl-branched alkanes (> 9.1 %). Two unassigned C31 monomethyl-branched alkanes were exclusively identified in male CWL extracts (∼ 4.7 %), while female samples contained high relative concentrations (> 22.5 %) of sterol derivatives, present only as minor constituents in male samples. Male T. pusillus performed sexually-oriented behavioral acts when paired with both live and dead conspecific females, intact or without the CWL. However, they ignored conspecific dead males. Our results show that CWL compounds have a role in intraspecific sexual recognition by male T. pusillus but only the CWL compounds does not explain mate recognition.

Keywords: Chemical cues; Courtship behavior; Cuticular compounds; Sex pheromones.