抄録
When pigmy mole crickets, Tridactylus japonicus DE HAAN, were grasped they often discharged a characteristic scent. It was believed this scent to be a defensive weapon against predators and some experiments were performed to confirm this idea. Two groups of crickets, one which had discharged the scent when held by human fingers prior to the experiment, and the other which was not held and had not discharged the odor were respectively introduced into petri dishes that had previously confined one Lacosid spider, Pardosa spp. The death rate of the scent-discharging crickets after 24 hr was 65% (N=20), while in the other group the death rate was 26.3% (N=19). A significant difference between them was found at the 5% level. Also, in another experiment, it was found that filter paper soaked with the odoriferous cricket's secretion repelled ants, Tetramorium caespilum L. These findings indicated that the scent emitted by the crickets acted as their defense against predators. This is the first report of a chemical defense utilized by Tridactyloid insects.
