Pests of the Endangered Herb Platycodon grandiflorus in Central Japan

Platycodon grandiflorus (Jacq.) A.DC. is a perennial herb in the Campanulaceae, whose wild populations in Japan are declining dramatically. As Strongylocoris leucocephalus (L.) (Hemiptera: Miridae) infests Campanula spp. in western Eurasia, and Adenophora triphylla (Thunb.) A.DC. var. japonica (Regel) H.Hara is a common pest in Japan, they may also be potential pests of P. grandiflorus. Field surveys, however, indicated that S. leucocephalus never infested P. grandiflorus, but that Tetranychus kanzawai Kishida (Acari: Tetranychidae) did. In addition, S. leucocephalus never fed on P. grandiflorus in the laboratory. Our results suggest that T. kanzawai is an important pest of P. grandiflorus, but that S. leucocephalus is not a potential pest of this endangered plant.