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

Abstract

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.

External morphology of the mouthparts and observations on behavior of Tuckerella japonica on Camellia sinensis in the continental USA

“…The diameters of the two stylets combined ranged from 1.6 to 2.3 µm and were consistent with observed stylet punctures in the periderm (Achor et al 2017 ). Unlike spider mites, T. japonica adults may have the potential to access outer phloem tissues with their saliva in 2-year-old stems of C. sinensis based on stem diameters, cell depth and stylet lengths (Achor et al 2017 ) but this has to be verified experimentally.…”

“…Tuckerella japonica injects saliva resulting in cell wall disruption and collapsed cells and, in older tissue, induces hyperplasia occurring in the cortical layer of cells (Achor et al 2017 ). As with other studied tetranychoids, the stylets are retracted, the infracapitular tip remains pressed on the wound and pre-digested liquefied cell contents are drawn back into the gut through the pre-oral food channel.…”

“…Achor et al ( 2017 ) found the range of potential stylet depth into plant tissues for T. japonica was 92–150 µm for T. japonica as compared to 70–120 µm for several spider mite species (Avery and Briggs 1968 ; Tomczyk and Kropczynska 1985 ). The diameters of the two stylets combined ranged from 1.6 to 2.3 µm and were consistent with observed stylet punctures in the periderm (Achor et al 2017 ).…”

“…Achor et al ( 2017 ) found the range of potential stylet depth into plant tissues for T. japonica was 92–150 µm for T. japonica as compared to 70–120 µm for several spider mite species (Avery and Briggs 1968 ; Tomczyk and Kropczynska 1985 ). The diameters of the two stylets combined ranged from 1.6 to 2.3 µm and were consistent with observed stylet punctures in the periderm (Achor et al 2017 ). Unlike spider mites, T. japonica adults may have the potential to access outer phloem tissues with their saliva in 2-year-old stems of C. sinensis based on stem diameters, cell depth and stylet lengths (Achor et al 2017 ) but this has to be verified experimentally.…”

“…Significantly greater numbers of T. japonica were found on the periderm of 2-year-old stems versus 1- or 3+-year-old stems and were rarely found on leaves. Mites fed on the periderm and underlying cortical tissues as well as on maturing green seed pods of the tea plants (Childers et al 2016 ; Achor et al 2017 ). No studies show how and where tuckerellid species feed on their respective host plants.…”