Worker aggression of ant Lasius japonicus enhanced by termite soldier–specific secretion as an alarm pheromone of Reticulitermes speratus

Abstract

AbstractThe subterranean termite Reticulitermes speratus usually nests in rotten wood trunks, which may also be occupied by the Japanese garden ant Lasius japonicus. Few battles were observed between them under ordinary circumstances because they inhabit separate nesting sites. However, once the termite nesting sites were artificially broken, the ant workers invaded and hunted the termites, although the termite soldiers fought against the ants. This study aims to confirm intra‐ and inter‐specific chemical interactions between the termite and ant. Solid phase microextraction–gas chromatograph (SPME‐GC) analyses revealed that R. speratus soldiers secreted caste‐specific sesquiterpene hydrocarbon when they were irritated. Both the hexane extract of the soldiers and its hydrocarbon fraction, as well as the crushed soldier bodies, attracted the soldiers but dispersed the workers when presented on the trails. We also confirmed that the soldier chemicals enhanced aggressiveness of L. japonicus, which rushed around the odor sources and hunted any termites that were present. These findings suggest that: (i) the soldier–specific secretion might serve as an alarm pheromone in termite chemical communication, in which components recruit soldiers and also warn the other colony members away; and (ii) termite communication is eavesdropped on by L. japonicus workers to locate and hunt the termites.