| Title: | Dorsal setae in Raoiella (Acari: Tenuipalpidae): Their functional morphology and implication in fluid secretion |
| Author(s): | Di Palma A; Beard JJ; Bauchan GR; Ochoa R; Seeman OD; Kitajima EW; |
| Address: | "Department of Agriculture, Food, Natural Science and Engineering (DAFNE), Food Environment, University of Foggia, Foggia, Italy. Electronic address: antonella.dipalma@unifg.it. Queensland Museum, South Brisbane, Queensland, 4101, Australia. Electron and Confocal Microscopy Unit, ARS-USDA, BARC, Beltsville, MD, 20705, USA. Systematic Entomology Laboratory, ARS-USDA, BARC-West, Beltsville, MD, 20705, USA. Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Universidade de Sao Paulo (USP), 13418900, Piracicaba, SP, Brazil" |
| DOI: | 10.1016/j.asd.2020.101023 |
| ISSN/ISBN: | 1873-5495 (Electronic) 1467-8039 (Linking) |
| Abstract: | "The setae of mites are not regarded as secretory structures, yet in the flat mite genus Raoiella, each developmental stage presents droplets of fluid associated with the tips of their dorsal setae. To understand the origin of this fluid, the ultrastructure of the dorsal setae is investigated in females of Raoiella bauchani Beard & Ochoa and the invasive pest species Raoiella indica Hirst using scanning and transmission electron microscopy techniques. The dorsal setae are barbed along their entire length and have either a broadened plumose or a flat spatulate tip. Ultrastructurally, they present the typical features of mechanoreceptors, but have a 'hollow' axis represented by a protoplasmatic core containing dendritic branches. This combination of ultrastructural characters indicates that the setae might be multimodal receptors: acting as both mechanoreceptors and contact chemoreceptors. The epidermal cells that underlie the setal sockets are columnar and have an ultrastructure that suggests they have a glandular function. Moreover, these cells present regular microvilli apically and form extracellular cuticular canals, containing epicuticular filaments, that are connected with the microvilli proximally and which open via pores onto the surface of the setal base distally. This arrangement indicates that the secretion from the microvilli passes into the canals and is then conducted to pores at the base of the seta, where it then accumulates and moves up the setal shaft, along the longitudinal grooves of the barbs. Based on similar arrangements in some insect taxa, the organization of the structures here observed in Raoiella suggests the passage of a non-polar, water insoluble, lipoid fluid through the cuticle, the function of which is still obscure" |
| Keywords: | "Animals Chemoreceptor Cells/ultrastructure Female Mechanoreceptors/ultrastructure Microscopy, Electron, Scanning Microscopy, Electron, Transmission Mites/*ultrastructure Sensilla/*ultrastructure Species Specificity Chemoreceptors Glands Mechanoreceptors P;" |
| Notes: | "MedlineDi Palma, Antonella Beard, Jenifer J Bauchan, Gary R Ochoa, Ronald Seeman, Owen D Kitajima, Elliot W eng England 2021/01/06 Arthropod Struct Dev. 2021 Jan; 60:101023. doi: 10.1016/j.asd.2020.101023. Epub 2021 Jan 2" |
