Synchronism of immigration of adult yellow tea thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) to citrus orchards with reference to their occurrence on surrounding host plants

Abstract

Scirtothrips dorsalis adults generally immigrate to citrus orchards after propagation on suitable host plants that grow near the orchards; however, it is not clear when these thrips immigrate. In this study, the time of S. dorsalis adult immigration to citrus orchards was examined in relation to their occurrence on surrounding host plants. The investigation was carried out in citrus orchards and the surrounding fields of the following three plants: tea groves, bigleaf podocarp trees, and Japanese pear trees. The average number of adults emerging from these four plant fields gave six or seven peaks from May to early September, notwithstanding the small number of adults emerging from the citrus orchards. The peak periods of trap catch in citrus orchards coincided with those of adult emergence from the fields of four plants. The peak periods of adult S. dorsalis density on citrus fruits and shoots coincided with those of trap catch in citrus orchards. These results demonstrated that S. dorsalis adults immigrated to citrus orchards immediately after emerging from other suitable host plants surrounding the orchards.