Western flower thrips (Thysanoptera: Thripidae) Frankliniella occidentalis is one of the most important pests of bell pepper which causes a decrease in the bell pepper yield through direct feeding on flowers, fruits and leaves and also indirectly by transmitng plant viruses in greenhouse and field crops. Although the use of insecticides is the main method to control this pest, the resistance of thrips to different chemical groups insecticides has turned the attention towards its integrated managment. In order to eva‎luate bell pepper cultivars resistance to this pest, the performance of thrips on six commercial cultivars including Nirvin, Massilia, Tormes, Caoba, Lorca and Inspiration was investigated using the life-fertility table parameters. Also, the oviposition preference of thrips on different bell pepper cultivars was studied in the choice experiment. To estimate the life-fertility table parameters, 100 new born larvae were placed individually on the leaf discs of each plant variety and they were checked daily until the death. To determine the oviposition preference, leaf discs of bell pepper cultivars were placed at the disposal of thrips for egg laying at the same time for 24 hours and then the number of new born thrips was counted during 5 days on each cultivar. All experiments were carried out at 25±1°C, 65±5 RH and 16L:8D photoperiod in the laboratory condition. The results showed that the population density and oviposition of western flower thrips were significantly affected by bell pepper cultivars. The shortest immature developmental time of thrips were 13.76 and 13.88 days on Massilia and Nirvin cultivars, respectively, and the longest was observed on Tormes cultivar, (16.28 days). The longest and shortest oviposition period of the thrips were recorded to be 9.19 and 3.50 days on Nirvin and Tormes cultivars, respectively. Also, the thrips fecundity was affected by the cultivars, so that the highest amount was observed on Nirvin cultivar with 22.91 offspring/female, and the lowest on Tormes cultivar with 4.01 offspring/female. The net reproduction rate of thrips was 2.25 births on Tormes cultivar and 12.83 births on Nirvin cultivar, respectively, as the highest and lowest values. The highest rate of intrinsic rated increase and the finite rate of increase of the thrips population were observed on Nirvin and Masilia cultivars, and their lowest value was observed on Tormes cultivar. The highest number of thrips eggs was recorded on the Nirvin (22.72 offspring/female) and the lowest on Tormes cultivar (1.50 offspring/female). According to the results, Nirvin cultivar was the most suitable cultivar among the bell pepper cultivars studied in this research, to support the western flower thrips population and Tormes cultivar was recognized as the most unsuitable host. the obtaned results can be used in selecting sweet pepper cultivar in the integrated pest management programs of western flower thrips.

نفيسه پورجواد

لادن طلايي

جهانگير خواجه علي، حسن كريم مجني