Mahdi Hassanpour - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.
Alireza Yaghmaee - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.
Ali Golizadeh - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.
Hooshang Rafiee-Dastjerdi - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.
Leila Mottaghinia - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.

In this study, the effect of three temperatures was investigated on the functional response of Orius laevigatus to Aphis gossypii in climatic chambers at ۲۰, ۲۵, and ۳۰ ± ۱ °C, ۶۰ ± ۵% RH, and ۱۶:۸ h photoperiod. Different densities of first and second instar nymphs of A. gossypii (۲, ۴, ۸, ۱۶, ۳۲, and ۶۴) on cucumber leaf discs (۶ cm in diameter) were separately offered to male and female predators. After ۲۴ h, the number of consumed preys was recorded. Ten replicates per each aphid density were used. Based on the results, predator male and female exhibited types II, III, II and III, II, III functional responses at ۲۰, ۲۵ and ۳۰ °C, respectively. Handling times (Th) for males were ۰.۷۷۹۸, ۰.۹۱۷۷ and ۰.۴۴۷۶ h and for females were ۰.۶۸۷۴, ۰.۳۹۲۱ and ۰.۲۸۳۱ h at ۲۰, ۲۵ and ۳۰ °C, respectively. Using the indicator variable method, pairwise comparisons of handling times of both males and females were significantly different. The theoretical maximum predation rate (T/Th) of both males and females were obtained at ۳۰ °C. The results revealed that O. laevigatus is more likely to be an effective biocontrol agent of A. gossypii at higher temperatures around ۳۰ °C. However, additional studies under natural conditions are needed to provide further details of the predator-prey interactions.

Predatory bug, melon aphid, cucumber, predator-prey interaction, temperature