Functional response of green lacewing, Chrysoperla zastrowi silemmi (Esben-Petersen) to its prey, cabbage aphid, Brevicoryne brassicae L.

Functional response influences the prey-predator interactions and hence is crucial for assessing the predatory potential of a given species. Laboratory studies were conducted at Dr. Y. S. Parmar University of Horticulture and Forestry, Solan, Himachal Pradesh, India during 2019-20 to assess the functional response of a generalist predator, Chrysoperla zastrowi sillemi (Esben-Petersen) (Neuroptera: Chrysopidae) against the cabbage aphid, Brevicoryne brassicae L. The feeding efficiency of larvae of C. zastrowi sillemi against varying densities of aphid i.e. 5, 10, 15, 20 and 30 was evaluated. The number of aphids consumed differed with prey densities and it was in direct proportion to the host density. All the three instars of C. zastrowi sillemi followed type II functional response. The attack rate (a) of the third instar larvae was maximum compared to first and second instars indicating the higher efficiency of later instar in prey consumption. Other parameters viz., the effectiveness of predator (a/th) and maximum predation rate (K) also followed similar trend while the prey handling time (Th) by the first instar took longer period (0.50 h) compared to second and third instars (0.46 h and 0.27 h, respectively). Searching efficiency was highest in the third instar which can be attributed to the higher mobility of fully grown larvae.