Interaction effect between time and cultivar on the parasitism percentage of the safflower fly, Acanthiophilus helianthi (Rossi) (Diptera: Trypetidae)

The safflower fly, Acanthiophilus helianthi (Rossi) (Diptera: Trypetidae), is one of the most important pests of safflower in the world, causing a lot of damage to this crop every year. In Iran, the seed yield loss due to the safflower fly is estimated to be 30- 70 % for different safflower cultivars. The use of parasitoids is one of the pest management methods. In this study, the interaction between time and cultivar on the parasitism rate of safflower fly by two parasitoid species of Microdontromerus annulatus and Ormyrus gratiosus was investigated in the research field of Shahed University (south of Tehran). The study was conducted under a Completely Randomized Block Design with four replications. The treatments consisted of seven safflower cultivars including Zarghan, Padideh, Goldasht, Varamin, Pourdad PI, Acataria, Mec163. Sampling was performed every seven days and data analysis was done by the Kruskal Valis method. The highest percentage of parasitism by O. gratiosus on 19 July was observed on Mec163 and Varamin cultivars (12.35%). The lowest percentage of parasitism by this species was observed on 14 June in all cultivars. The highest parasitism rate by M. annulatus during the sampling period was observed on Padideh (7.56%) and Mec163 (7.52%) cultivars. The lowest percentage of parasitism (49.6%) by M. annulatus was observed on Varamin cultivar.