Dead-twig discrimination for oviposition in a cicada, Cryptotympana facialis (Hemiptera: Cicadidae)

Abstract

In phytophagous insects, in spite of some general advantages of oviposition on a vital part of their host food plants, certain species prefer dead tissues for oviposition. In the present study, we examined oviposition-related behaviors of a cicada, Cryptotympana facialis (Walker), which lays eggs exclusively into dead twigs. From behavioral observation of females experimentally assigned to live or dead plant material, we found that egg laying into freshly cut live twigs is abandoned in two phases, i.e., before and after initiation of egg nest-creating behavior with the ovipositor. Behavioral sequence analyses revealed that oviposition was generally preceded by rubbing with the rostrum tip and brief stylet-penetration behavior, suggesting that oral assessment may play a primary role in decision-making of oviposition in the earlier discriminating phase. From the similarity in behavioral flows of this assessment to vital tissue-seeking behaviors, cicada females are presumed to judge a twig as dead by sensing the absence of vital cues. These findings contribute to understanding a behavioral basis of dead plant recognition for oviposition, potentially giving an insight into ecological and evolutionary aspects of diverse oviposition preferences.