Functional Response of Four Predaceous Coccinellids, Adalia tetraspilota (Hope), Coccinella septempunctata L., Calvia punctata (Mulsant) and Hippodamia variegata (Goeze) Feeding on the Green Apple Aphid, Aphis pomi De Geer (Homoptera: Aphididae)

Functional responses of four coccinellids, viz., Adalia tetraspilota (Hope), Coccinella septempunctata L., Calvia punctata (Mulsant) and Hippodamia variegata (Goeze), were evaluated under laboratory conditions to find out how these predators responded to density of the prey species, green apple aphid Aphis pomi De Geer. All the coccinellid species exhibited a convex (Type II) functional response determined by a non-linear model. The non-linear reciprocal transformation of Hollings. disc equation was used to estimate the parameter values of the model. The large predator, C. septempunctata was seen to eat more aphids due to its greater voracity as compared to the smaller species C. punctata, H. variegata and A. tetraspilota. C. septempunctata had higher search rate than C. punctata, H. variegata and A. tetraspilota, whereas the handling time showed the opposite trend as the search rate. The results suggest C. septempunctata is the best predator for the biocontrol of Aphis pomi. Further field-based studies are required to confirm this hypothesis.