CREONTIADES PALLIDUS به تراكم هاي مختلف پوره هاي سنگ قوزه پنبه CHRYSOPERLA CARNEA و NABIS CAPSIFORMIS واكنش تابعي شكارگرهاي

Functional Response of Predators Nabis Capsiformis and Chrysoperla carnea to Different Densities of Creontiades pallidus Nymphs

Functional responses of adult females of Nabis capsaformis and second instar larvae of Chrysoperla cornea to different densities of second instar nymphs of Creontiades pallidus were determined. In addition to type of functional response, the rate of searching efficiency, handling time, and related parameters were estimated. Second instar nymphs of C. pallidus in densities of 2, 4, 8, 10, 20 and 30 were presented to females of N. capsaformis and larvae of C. cornea for 24 hours in 10 replications, and then the numbers of eaten preys were counted. Analysis of functional response was conducted in two stages using Juliano method. Logistic regression indicated that the functional responses of both predators to different densities of C. pallidus nymphs were type II. Holling disc equation was used for estimating functional response parameters. The values of searching efficiency (a), handling time (Th), the rate of fitting of data to model (r^2), maximum estimated rate of eaten preys (T/Th) and maximum observed rate of eaten preys (Namax) for N. capsaformis were 0.039, 1.82, 0.89, 13.19 and 13, respectively and for C. cornea were 0.041, 1.11, 0.97, 21.69 and 15, respectively. The results indicated that the second instar larvae of C. cornea were more successful in attacking to their prey in comparison with adult females of N. capsaformis.