Host stage preference and functional response of aphid parasitoid Diaeretiella rapae (McIntosh) (Hym.: Braconidae) on greenbug, Schizaphis graminum (Rondani) (Hem.: Aphididae)
2010
Dashti, H. | Shahrokhim, Sh. | Zarrabi, M. | Rezapanah, M.R
Searching capacity is of importance in effectiveness of natural enemies. In this research, the host stage preference and functional response of Diaeretiella rapae (McIntosh) to different densities of greenbug, Schizaphis graminum (Rondani) were determine on Pishtaz wheat leaves at condition of 25 ± 1 ºc, 60-70% RH, and a photoperiod of 16: 8 h (L:D). Host stage preference was investigated by referring 50 number of first to fourth instar nymphs and wingless adults of greenbug to individual parasitoid females at 8 replicates. Results indicated significant preference of D. rapae to second instar nymphs of graminum To perform functional response experiment, densities of 2, 4, 8, 16, 32, 50, 64, 90 and 130 second instar nymphs of greenbugs were referred to individual mated female wasps at 10 replicates for 24 hours. Type of functional response was determined by logistic regression and its parameters, attack rate (a) and handling time (Th), were estimated by non-linear regression. The results indicated that functional response of D. rapae was from type III and value of handling time was calculated as 0.358.
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