We measured predation rate of several developmental stages of two aphidophagous predators - larvae of lacewing Chrysoperla carnea (Stephens) (Neuroptera Chrysopidae) and larvae and adults of ladybird Hippodamia variegata (Goeze) (Coleoptera Coccinellidae) combined together in the same experimental arena. Two arenas with different complexity but similar surface were compared, simple with aphids on a leaf of host plant, and microcosm with potted plant Vicia faba L. The initial number of prey, larvae of aphid Aphis fabae Scopoli (Rhynchota Aphididae), was set up to 50, 150 and 400 individuals. The first day of experiment, after previous starvation, the pair of predators exhibited type I functional response. The second and third days, after feeding ad libitum, the predators exhibited type II functional response. Consumption rate was lower on the second day (130 aphids of 400) than on the first day (180 aphids) in the simple arena, probably due to an effect of starvation vs. feeding ad libitum. Consumption increased day after day in the microcosm arena (1st day: 30 of 400 aphids, 2nd day: satiation limit 174 aphids / 3rd day: 261 aphids), probably due to the habituation to the complex environment. Overall predation rate and control mortality of aphids without predators at the microcosm arena were lower than in the simple arena.
