Neda Kasraee - Department of Plant Protection, Faculty of Agriculture, Razi University, Kermanshah, Iran.
Shahriar Asgari - Department of Plant Protection, Tehran Agricultural and Natural Resources Research and Education Center, AREEO, Varamin, Iran.
Abbas Ali Zamani - Department of Plant Protection, Faculty of Agriculture, Razi University, Kermanshah, Iran.
Naser Moeeny Naghadeh - Department of Plant Protection, Faculty of Agriculture, Razi University, Kermanshah, Iran.
Seyed Mahdi Mahjoob - Department of Plant Protection, Kermanshah Agricultural and Natural Resources Research and Education Center, AREEO, Kermanshah, Iran.

The functional response of the egg parasitoid, Trissolcus vassilievi (Nees) (Hym., Scelionidae), on eggs of the sunn pest, Eurygaster integriceps Put. (Hem., Scutelleridae) was investigated at six constant temperatures (۱۲, ۱۵, ۲۰, ۲۵, ۲۸ and ۳۲ °C) for ۸ hours. Using logistic regression, a type III functional response was determined for T. vassilievi at the two temperatures ۱۵ and ۳۲ °C. Any functional response was not detected at other temperatures. The Hassells’ type III model was used for estimating searching efficiency (a) and handling time (Th). At ۳۲ °C the highest attack rateand the lowest handling time was recorded ۰.۲۰۲۹ per hour and ۰.۱۸۵۶ hour, respectively. Results show that the parasitoid can be used in the pest management programs at low and high temperatures.

Biological control, cereal bug, parasitoid behavior, temperature