Effects of Emamectin Benzoate and Methoxyfenozide on Functional Response of Trichogramma brassicae (Hym: Trichogrammatidae)

Insecticides applications may affect behavior of natural enemies such as functional response. The effects of LC30 (as sublethal concentration) of emamectin benzoate and methoxyfenozide were evaluated on functional response of Trichogramma brassicae Bezdenko in different densities of Sitotroga cerealella Olivier eggs at 26±1oC، 70±5% RH and a photoperiod of 16:8 (L: D) h. Young adult wasps (<24h old) were exposed to LC30 of the either insecticides as well as a control. Then، randomly selected 10 survived females were transferred individually to test tubes and supplied with the host densities of 2، 4، 8، 16، 32 and 64 S. cerealella eggs for 24 h. The numbers of parasitized eggs were recorded seven days later. The type of functional response was determined using logistic regression and the parameters were estimated by non-linear regression using SAS software. The results revealed a type II functional response in control and methoxyfenozide and type III in emamectin benzoate. Attack rates were 0. 00183، 0. 001292 and 0. 001290 h-1 and handling times were 0. 4987، 0. 6247، and 0. 6174 h، in control، emamectin benzoate and methoxyfenozide، respectively. Results showed that these insecticides had little adverse effects on the functional response of the wasp. Field studies for assessing efficacy of the insecticides on T. brassicae are needed to obtain more reliable results.