Intraguild predation between two aphidophagous coccinellids, Hippodamia variegata (G.) and Coccinella septempunctata L. (Coleoptera: Coccinellidae): the role of prey abundance

Intraguild predation (IGP) is a common phenomenon among the predacious coccinellids which involves a combination of predation and competition. The aphidophagous predators, Coccinella septempunctata L. and Hippodamia variegata (G.) comprise major part of coccinellid predator species in the agroecosystem of Turkey. We investigated the IG interactions between these aphidophagous predators under laboratory conditions. Our results revealed that predation of the eggs of H. variegata by the adult male, female and 4th instar larvae of C. septempunctata was maximum at 0 prey abundance, however, substantial number of eggs were also consumed at aphid densities of 30 and 80. Consumption of 1st and 2nd instar larvae was also higher in the absence of aphids, intermediate at 80 aphid density and greatly reduced or almost negligible at 350 prey abundance. The same sequence was also true for the predation of the different juvenile stages of C. septempunctata by H. variegata adult male, female and 4th instar larvae. The adult female and 4th instar larvae of both C. septempunctata and H. variegata proved to be more voracious towards different heterospecific juvenile stages compared to adult male. Results on the preference of C. septempunctata and H. variegata towards conspecific or heterospecific eggs revealed that both the aphidophagous coccinellids showed higher degree of preference for egg cannibalism (conspecific egg consumption) over IGP (heterospecific egg consumption).