Cellular injury to 1- to 3+-year-old stems of Camellia sinensis by Tuckerella japonica

Tuckerella japonica Ehara (Acari: Tuckerellidae) feeds on predigested plant cells beneath exposed periderm tissue of 1- to 3+-year-old stems of Camellia sinensis (L.) O. Kuntze (Theaceae) where longitudinal bark splitting occurs. Control samples from these tissues were compared with areas fed upon by T. japonica adults and immatures to characterize types of cellular injury. Stylet diameters ranged from 1.6 to 2.3 µm and were consistent with observed stylet punctures in the stems. Mite saliva was injected along tracts within the cortical tissue and resulted in cell wall disruption, collapsed cells and, in older tissue, hyperplasia. The range of potential stylet penetration into plant tissues was from 92 to 150 µm. Tuckerella japonica injects saliva in the cortical tissues. The paired stylet lengths would allow for possible injection of saliva into the upper areas of phloem tissue but not in the cambium area of wood exposed by splitting of the outer epidermis.