Urticating Hairs in Arthropods: Their Nature and Medical Significance

Andrea Battisti; Göran Holm; Bengt Fagrell; Stig Larsson

doi:10.1146/annurev-ento-120709-144844

Urticating Hairs in Arthropods: Their Nature and Medical Significance

Andrea Battisti¹, Göran Holm², Bengt Fagrell², and Stig Larsson³
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Affiliations: ¹Department of Environmental Agronomy, University of Padova, Legnaro I-35020 Italy; email: [email protected] ²Karolinska Institutet, Karolinska University Hospital Solna, L08:00, Stockholm, S-17176 Sweden; email: [email protected]; [email protected] ³Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, S-75007 Sweden; email: [email protected]
Vol. 56:203-220 (Volume publication date January 2011) https://doi.org/10.1146/annurev-ento-120709-144844
First published as a Review in Advance on August 30, 2010
© Annual Reviews

Abstract

The ecological phenomenon of arthropods with defensive hairs is widespread. These urticating hairs can be divided into three categories: true setae, which are detachable hairs in Lepidoptera and in New World tarantula spiders; modified setae, which are stiff hairs in lepidopteran larvae; and spines, which are complex and secretion-filled structures in lepidopteran larvae. This review focuses on the true setae because their high density on a large number of common arthropod species has great implications for human and animal health. Morphology and function, interactions with human tissues, epidemiology, and medical impact, including inflammation and allergy in relation to true setae, are addressed. Because data from epidemiological and other clinical studies are ambiguous with regard to frequencies of setae-caused allergic reactions, other mechanisms for setae-mediated disease are suggested. Finally, we briefly discuss current evidence for the adaptive and ecological significance of true setae.

Keyword(s): ecology, epidemiology, immunology, Lepidoptera, seta, spider

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2011-01-07

2025-04-24

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Urticating Hairs in Arthropods: Their Nature and Medical Significance

Annual Review of Entomology 56, 203 (2011); https://doi.org/10.1146/annurev-ento-120709-144844

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Supplementary Data

Supplemental Figure 1. Silhouette representation of true urticating setae of spiders and insects. For scale reference, the setae inside the smaller circle are about 200 µm long. From left to right: spider type I, II, III, IV, and V (redrawn from Cooke et al. 1972, Perez-Miles 1998, Foelix et al. 2010); moth seta of Hylesia metabus type S4 [drawn from scanning electron microscopy (SEM) pictures in Rodriguez et al. 2004]; larval seta of Thaumetopoea pityocampa (drawn from SEM picture in Novak et al. 1987); larval seta of Euproctis chrysorrhoea (drawn from SEM picture in Jong et al. 1976).

Supplemental Figure 2. Schematic representation of the occurrence of urticating setae in larval instars of Thaumetopoea pityocampa (from Scheidter 1934) and Euproctis chrysorrhoea (from Werno & Lamy 1994). The setae appear during the larval development on the dorsal part of the abdomen in specific areas called mirrors (French “miroir,” German “Spiegel”) owing to their brightness and light reflectivity. The mirrors increase in number and size as the larva molts, and reach a full set consisting of several hundred thousand setae (630,000 in T. processionea Scheidter 1934, and up to one million in T. pityocampa, Lamy et al. 1982a) in the mature larva. New setae are produced at every molting.

Supplemental Figure 3. Schematic description of the mechanism by which the larva of Thaumetopoea pityocampa releases the setae (from Démolin 1963). The mirrors are kept folded under normal conditions (a, side view) and only the distal end of the setae is visible (larva on the left). When disturbed, the larva opens the mirror (b, side view; c, seen from above), resulting in the release of the setae (larva on the right).

Download Supplemental Figures 1-3 as a PDF.