Multiplication capacities of Tomicus piniperda L. (Col., Scolytidae). 1. Effects of attack density
1989
Sauvard, D. (Institut National de la Recherche Agronomique, Ardon, Olivet (France). Station de Zoologie Forestiere)
The effect of the attack density on the fecundity of the pine shoot beetle, Tomicus piniperda, was studied in laboratory and natural conditions. Increasing densities (12.5 to 1600 females/square metres) were tested in controlled installation of insects. Increasing densities reduced the number of galleries bored by the females, their mean length and the related numbers of eggs and larvae. On the other hand, oviposition density remained constant. The decrease of the fecundity of the females was not sufficient to avoid an important rise of the number of eggs per unit of bark surface, and consequently a higher larval mortality in the high densities, as well as a reduction of the weight of the emergents. This control of larval surviving allows to obtain through a wide range of attack densities a constant number of emergents per unit of bark surface
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