Détail de la référence

Contact dermatitis (erucism) produced by processionary caterpillars (genus Thaumetopoea)

Auteur : Lamy (Michel)

Année de publication : 1990
Publication : Journal of Applied Entomology (= Zeitschrift für Angewandte Entomologie)
Volume : 110
Fascicule : 5
Pagination : 425-437

Résumé :

Urticating hairs of Thaumetopoea pityocampa caterpillars cause cutaneous reaction in men and animals. This contact dermatitis is known as erucism. Conjunctivitis, sometimes keratitis and even uveitis can be associated with the contact dermatitis. Asthma and anaphylactic shock require admission to intensive care unit. The urticating hairs are located on 8 abdominal 'mirrors'. A morphological study of the urticant apparatus was undertaken using scanning electron microscope during the last three larval stages (L3, L4, and L5). The urticating hair, hollow inside, carries pointed spikes directed towards its distal end. There is no hole or pore on the hair. It is really a bulb which must be broken, for example in the skin, in order to release its urticant. An urticating gland, inside the thin cuticle of the 'mirror', produces hairs and urticant. Histological and immunological methods were used to study cellular differentiation of the urticating gland during larval development. Only trichogen cells form it. These cells form an irregular cluster, which seems to be multilayered, although there is only one layer of cells. This gland is present early in the 1st instar and becomes thicker during further development. Only in the 3rd instar does this gland begin to produce urticating hairs and the thin cuticle in which the hairs are implanted. It also produces urticating substance. The urticating substance, extracted from hairs, contains soluble proteins which were separated by various electrophoretic and immunoelectrophoretic techniques. Some of these proteins are present also in cuticle and haemolymph. One protein of 28 000 daltons, formed of two subunits, is hair specific and causes a reaction in guinea-pig skin (histamine-releasing effect) identical to that produced by hair extract. It is, therefore, an urticating protein which we have named Thaumetopoein. It is present in large quantity in the gland which produces urticating hairs