A. R. Askarianzadeh, S. Moharramipour, Y. Fathipour, A. Narrei,
Volume 12, Issue 45 (10-2008)
Abstract
Cultivars or species of different plants through physical and biochemical characteristics or indirectly through food diet of host plant can influence behavioral characteristics and efficiency of a natural enemy. This investigation was conducted to determine percentage of parasitism and functional response of parasitoid wasp, Platytelenomus hylas (Hym., Scelionidae) to different egg densities of stem borer, Sesamia nonagrioides (Lef.) and effect of different cultivars on it. At the first stage, eggs of pest were separately collected from fields in three cultivars of CP48-103, CP69-1062 and CP57-614 and then percentage of parasitism in each cultivar was calculated. For determining functional response of the wasp, collected eggs from fields were reared to adult stage at 29±1 ºC, 60% of RH,. Then functional response of wasp was investigated at densities of 2, 4, 6, 8, 14, 20, 30, 40, 50, 60, 70, 80, and 90 of the host eggs for 24h. Analysis of data was done using SAS software. Results showed that egg parasitism by P. hylas in cultivars were significantly different (p<0.05). Type of cultivars influences rate of egg parasitism. Comparison of means by Duncan’s test showed that CP48-103 cultivar significantly differed from two other cultivars: CP69-1062 and CP57-614. Functional response in three cultivars was found to be a type III. Comparison of estimated parameters by Holling model in three cultivars showed that searching efficiency on CP48-103 cultivar was significantly higher than two other cultivars but CP57-614 and CP69-1062 were close to each other. Also, handling time (Th) and the maximum rate of estimated parasitism (T/ Th) on the three cultivars were different and on CP69-1062 they were significantly less than the two other cultivars.
