Effects of Hexaflumuron and Spirodiclofen on Functional Response of Hippodamia variegata at Different Densities of Agonoscena pistaciae

Common pistachio psylla, Agonoscena pistaciae Burckardt and Lauterer (Hemiptera: Aphalaridae) is one of the economical pest among the pistachio orchards. The adoni's ladybird, Hippodamia variegata (Goeze) (Col: Coccinellidae) is one of the most prominent coccinellid predator in pistachio orchards. It is omnivorous and feed on aphids and psylla. Functional response studies using a suitable index of the successful of natural enemy in the biological control programs for pests. Sometimes the application of pesticides have indirect effects on functional response and related behaviors of predators. In this study, the effects of insecticide: hexaflumuron and acaricide spirodiclofen were investigated on functional response of the 4th instars larvae of H. variegata in controlled conditions (26±2ºC, 60±5٪ RH, 16L: 8D). For this purpose, different densities including 4, 8, 16, 32, 64, 95, 128, 150, 200 and 300 5th instars nymphs of common pistachio psylla were placed on pistachio leaf disc in a petri dish. Larvae were treated with field recommended concentration by topical application method. Type of functional response, the searching efficiency (a) and handling time (Th) were estimated by using logistic regression and non-linear regression methods, respectively using SAS software. According to the result, functional response was type II in all treatments. Searching efficiency in hexaflumuron, spirodiclofen and control were estimated 0. 077±0. 014, 0. 098±0. 030 and 0. 125±0. 245 h-1, and for handling time were 0. 13±0. 017, 0. 11±0. 023 and 0. 01±0. 12 h respectively. This achievement shows that these pesticides do not change the potential of H. variegata significantly.