The functional response of Aphidius ervi (Haliday)(Hym.: Braconidae, Aphidiinae) to different densities of Sitobion avenae (Fabricius)(Hom.: Aphididae) on two wheat cultivars

The functional response of Aphidius ervi to different Sitobion avenae densities on two wheat cultivars (Sardary and Alvand) was examined in laboratory conditions. Experiments were carried out in test tubes on an F۲ lab generation without wheat clusters and also on F۲ and F۵ generations in pots using wheat clusters. In the tubes, female wasps were exposed to aphid densities of ۲, ۴, ۷, ۱۴, ۲۸, ۳۲, ۴۲ and ۵۶ for one hour, but on the potted plants, to the same densities of aphids for ۲۴ hours. Results obtained from the logistic regression indicated types II (Holling’s model) and III (Roger’s model) in all ۳ experiments on Alvand as a resistant cultivar and Sardary as a sensitive cultivar, respectively. The type II model of functional response fitted on data obtained on the Alvand cultivar indicates a negative bottom top impact of the resistant cultivar on the parasitoid. The model parameters estimated for F۲ and F۵ wasps were not significantly different for the Sardary cultivar. However, the area of discovery and handling time in the F۵ generation on the Alvand cultivar were higher than that of F۲.

کلیدواژه ها:

Aphidius ervi ، Functional response ، Sitobion avenae