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Le Bombyx Cul-brun, Euproctis chrysorrhoea. (1). Écologie - Nuisibilité

Auteurs : Torossian (Claude), Roques (Lydie) et Torossian (Fernand)

Année de publication : 1988
Publication : Bulletin de la Société d'Histoire naturelle de Toulouse
Volume : 124
Pagination : 127-174

Résumé :

Determinism and frequency of gradations - Our researchs are demonstrated the existence of several demographic states: a) Endemic state in which the species very scarce is practically invisible. b) aperiodic gradation state during 3-4 years the species is a real social flail. c) Undergradation state in which the species is strongly established in the country. From this biological centers it can invade during 8 or 10 years all forests of large countries. We can establish this new state in "Midi-Pyrenees" [France] and "Loire-Atlantique" countries. Importance of hedges (hawthorn...) - Hedges are un unknown habit (well appreciate for the brown tail moth), in which the species can increase the populations. Hedges constitute an important habitat and allow very easily return of gradation. Treatment window's - The biological cycle show two times which permit phytosanitory interventions: during on post-hibernation caterpillars, and in summer on pre-hibernating caterpillars (very young larvae). We are in experiments on these two windows (microbiological and chemical process integreted to biological auxiliary insects). Euproctis chrysorrhoea is very well knowed defoliating butterfly till 15 years by its heavy outbreak of caterpillars in Midi-Pyrenees. Bioecology - The brown tail, polyphagous and ubiquist species is living on all types of environment. In Midi-Pyrenees, his elective habitat is oak forest; Lymantria dispar and Euproctis chrysorrhoea constitute the most injurious pests for this type of forest. It prefers opened and anthropised areas, but it can also invade regularly deep forests (Bouconne, Mauboussin...). It can be considered as one of the most dangerous pest. His caterpillars are urticating in all stages, mainly at the end of development (L4-L5). The development of this species may be schematicaly described in 3 stages well separated: 1.degree. - The pre-hibernating caterpillars (L1, L2, L3): epidermic leaf cutting caterpillar (low noisy). 2.degree