Phenological asynchrony often occurs between organisms because of their different responses to temperature. Such asynchrony may alter the strength and direction of selection pressure for organisms and affect their interactions.

We investigated in the field the leaf production phenology of an extrafloral nectary (EFN) bearing plant Mallotus japonicus<i/> (Euphorbiaceae) and its interactions with mutualistic ants and a specialist herbivore Eschatarchia lineate<i/> (Leipdoptera: Geometridae) at Okinawa and Amami, and then performed greenhouse and transplant experiments to confirm whether plant defense traits differ between sites and the defense strategies are adaptive at their original sites.

As a result, the seasonal pattern of leaf production did not differ between sites. Ant activity was lower but E. lineata<i/> larvae were more abundant in Okinawa than in Amami. Ant workers effectively removed E. lineata<i/> from M. japonicus<i/>. Okinawa population of M. japonicus<i/> invested more in direct defense traits but less in indirect ones including EFN than Amami population. The defense strategy of M. japonicas<i/> was clarified to be adaptive at the original sites. These results indicate that phenological asynchrony between the herbivore and predators configure the local adaptation of the plant.