The functional response of Chrysoperla externa (Hagen) fed on Schizaphis graminum (Rondani) was studied under five densities of prey. The experimental design was completely randomized with five treatments and ten replications. The tests were conducted in growth chambers at 25 ± 1ºC, RH of 70 ± 10% and photophase of 12 hours. Consumption increased in function of prey density in all instars. However, consumption tended to stabilize when a pre established average density of prey was offered, except for the first instar, which showed a constant increase in aphid consumption. The duration of the first and third instars and of the larval phase, as a whole, increased in function of the increased availability of prey. The duration of the second instar, however, decreased in function of increased prey availability. The results for the 1st, 2nd and 3rd instars and the larval phase showed a Type II functional response. Handling and searching time was evaluated for the average density of offered prey. The lowest searching time was verified for second instar larvae while the first instar showed the highest searching and handling time. Handling time dimi-nished progressively with larvae development.
Insecta; green lacewing; predation; consumption; searching time; handling time
