Partial life table analysis for larval Coleomegilla maculata (Degeer) and Coccinella septempunctata L. (Coleoptera: Coccinellidae) in alfalfa

Eggs, larvae, and adults of the introduced Palearctic species Coccinella septempunctata L. and the indigenous Coleomegilla maculata (Degeer) were sampled in spring alfalfa along with their prey, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), to determine their temporal occurrence, rate of survival, and density of A. pisum. A partial life table was constructed for the first, second, and third instars of both coccinellid species. The larvae and adults of both predators overlap spatially and temporally in spring alfalfa, and mortality from first instar through third instar was high for both species (93.0% for C. maculata and 90.8% for C. septempunctata). Adult density ranged from 7.0 to 11.8 adults per m² for C. maculata and from 5.9 to 11.8 adults per m² for C. septempunctata. The density of A. pisum ranged from 5.4 to 116.7 aphids per m².