Influence of number of larvae in the colonies on the induction of diapause in Diprion pini L. (Hym., Diprionidae)
1989
Geri, C. (Institut National de la Recherche Agronomique, Olivet (France). Station Zoologie Forestiere) | Goussard, F.
Two experiments were carried out in 1987 and in 1988. Groups of Diprion pini larvae different by their numerical importance were reared with adequate supply of food. 200 larvae groups give more diapausing eonymphs than 100 larvae or smaller groups. Diapause rates of these latter groups, which agree with usual size of larval colonies in nature, are not statistically different. This phenomenon, as quantitative and qualitative food deficiency, is likely a cause of the high diapause rates observed in D. pini natural populations when outbreaks fall. Unlike alimentary factors, importance of colonies is of few effect on other characteristics of the sawfly development
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