The adaptive plasticity of parasitoid Acerophagus papayae noyes and Schauff on different host plants using the handling time, recognition time and survival probability of parasitoid via the infestivity of parasitoids using the reciprocal experiment is demonstrated to prove the existence of co-evolutionary arms race between parasitoids and insect pest. Papaya had significantly lower handling time and recognition time of 20.4 seconds and 4.8 seconds respectively. tapioca had higher handling time and recognition time of 38.8 seconds and 8.8 sec respectively. the infestivity of A. papayae shows host preferences mediated through host fidelity of some populations, demonstrated by significant differences in infectivity across the different hosts studied. This could be used to increase the effectiveness of biological control programme.