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Différents états de diapause nymphale et stratégie d'hivernation de Heliothis armigera Hübn. (Lep., Noctuidae)

Auteurs : Buès (Robert), Gabarra (Rose), Hmimina (M'hamed) et Poitout (Henri Serge)

Année de publication : 1989
Publication : Journal of Applied Entomology (= Zeitschrift für Angewandte Entomologie)
Volume : 107
Fascicule : 4
Pagination : 376-386

Résumé :

In the south of France and in circum-mediterranean countries, H. armigera overwintering can either be induced by the interaction of autumnal temperatures and short days duration, which never concern the whole population, or by the sole action of low temperatures on the larval stage and the beginning of the nymphal stage. Under constant conditions and on the basis of the retention of diapausing nymphs eye spots, we could precise the cold-induced conditions of this diapause state. In non diapausing one-day-old nymphs the disappearance of eye spots is proportional to room temperature. It is then possible to determine a thermal threshold for development, nearing 10.degree. C. At low temperatures, ranging from 2 to 18.degree. c, the exposure of groups of last stage larvae and prenymphs and 1 to 2-days-old nymphs reared at 21.degree. CLO 16:8, induces a diapause state, which rate varies with temperature and stage at transfer. This diapause state leads to 2 types of nymphs, either showing a short nymphal development and an emergence thermal threshold greater than 15.degree. C, or a long nymphal development, with a higher thermal threshold (18 to 21.degree. C), similar to a diapause induction by a short photoperiod. From the above observations a coherent explanation of the species overwintering strategy could appear, particularly in the northern zones of its distribution area