Journal of Biological Control

Functional response of different larval instars, adult males and females of the predacious coccinellid, Harmonia eucharis (Mulsant), was evaluated under laboratory conditions to varying density of green apple aphid, Aphis pomi De Geer. The life stages of H. eucharis exhibited a curvilinear Type II functional response. The fourth instar larva of H. eucharis consumed more aphids (34.06 aphids/day each) due to its larger size and greater voracity as compared to first instar larva (14.73 aphids/day each), second instar larva (25.73 aphids/day each), third instar larvae (29.06 aphids/day each), adult female (28.06 aphids/day each) and adult male (22.06 aphids/day each). The search rate and handling time estimated for different stages of H. eucharis showed that the fourth instar had higher search rate, whereas the handling time showed the opposite trend as search rate. The results suggested that fourth instar larva of H. eucharis is the efficient predator for the biological control of A. pomi. Further field-based studies are needed to confirm this hypothesis.