Functional Response of Adult Male and Female of Hippodamia variegata Goeze (Col.: Coccinellidae) on Peach Aphid

Functional response, as describing the rates of predation in different prey density, and determining the predator efficiency, is important in the regulation of prey populations. The functional response of male and female adult of lady beetle, Hippodamia variegata, was studied at different densities of green peach aphid under laboratory conditions on canola Brassica napus L. (cv. RGS003). Nymphs were used to enhance the accuracy of contemporaries. The experiment was carried out on leaf disk of canola in Petri dish in 15-20 replicates. After 24 hours number of killed prey was recorded. The results showed that male and female of Hippodamia variegata revealed a type II functional response to different density of 2, 4, 8, 16, 32, 64, 80, 128 for female, and 2, 4, 8, 16, 32, 45, 70 for male. The rate of searching efficiency and handling time were assessed as 0.167 h-1 and 0.333 h for male, 0.135 h-1 and 0.193 h for female, respectively. By using an equation with indicator variable, functional responses of adult males and females were compared, it showed that searching efficiency had no significant differences, but comparisons of handling times showed significant differences. Thus it can be concluded that the ability of female predators is greater than the male to control the green peach aphid.