제주에서 볼록총채벌레 발생동태 및 피해지역 분포 특성

Abstract

Yellow tea thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), regarded as a key pest on citrus fruits in tropical or subtropical regions in South-East Asia, and is expected to increased by global worming. In Jeju Korea, the damage by this pest as subtropical weather condition will be intensified in the future. The S. dorsalis has over 150 host plants. Primary host plants are asparagus, kiwi, green tea, grape, carrot, bean, pear, potato, strawberry and so on. On the other hand citrus is known as secondary host plant of this thrips. But the fruit injury by S. dorsalis on citrus has been increased since 2007 in Jeju. Thus, this study was conducted to investigate the overwintering ecology and population dynamics of S. dorsalis in relation to primary host plants and citrus orchards in Jeju. Consequently, the objective of this study was to develop a management strategy of S. dorsalis in citrus orchards. The survey for overwintering sites indicated that overwintering S. dorsalis population was more in plant litters than in soil samples, and also the overwintering adults were found much more in kiwi orchards and tea farms (primary host plant) than in citrus orchards (secondary host plant). The population of adults found was 471 adults/kg in kiwi orchard, 19 adults/kg in tea farm, 77 adults/kg in two citrus orchards in 2010 sampling. When the samples of plant litters including overwintering S. dorsalis adults were held at constant temperatures, adult activity was high above 15℃, while a few adults were caught on a sticky trap installed at 15℃. The occurrence patterns of S. dorsalis in kiwi orchards and green tea farms in Jeju were different from one of S. dorsalis in citrus orchards, showing 6 to 7 generation cycles a year. While there is delayed occurrence of the overwintering generation or loss parts of the generations was observed in citrus orchards. This result showed that S. dorsalis scarcely used citrus orchards as its overwintering sites and could not survive successively on citrus. In other words, it was considered that the S. dorsalis populations multiplied on primary hosts, kiwi and green tea, migrated to adjacent host plants such as citrus trees, when they could not use food resources on the primary hosts. In kiwi orchards, young shoots were pruned to increase the quality of old leaves from June for the purpose of tree nutrient. Thus, S. dorsalis populations on kiwi might disperse to adjacent hosts, since they were subjected to food shortage. Consequently, a forecasting effort would be required to monitor S. dorsalis populations migrating from kiwi and green tea of primary host plants using sticky traps or visual observations. Furthermore, cover sprays might be conducted in citrus orchards including the source habitats of S. dorsalis.