HAL Id: hal-02817486
https://hal.inrae.fr/hal-02817486
Submitted on 6 Jun 2020
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Threshold of attack density by Ips sexdentatus on Pinus pinaster
François Lieutier, L. Connan, Jacques Garcia, Daniel Sauvard, Annie Yart
To cite this version:
François Lieutier, L. Connan, Jacques Garcia, Daniel Sauvard, Annie Yart. Threshold of attack density by Ips sexdentatus on Pinus pinaster. 8. European congress of entomology, Sep 2006, Izmir, Turkey. 1 p. �hal-02817486�
VIII th European Congress of Entomology. IZMIR, TURKEY, September 2006 17-22
Threshold of attack density by Ips sexdentatus on Pinus pinaster F. Lieutier1, L. Connan1, J. Garcia2, D. Sauvard2 &
A. Yart2
1. Université d’Orléans, Laboratoire de Biologie des Ligneux et des Grandes Cultures, UPRES EA 1207, B.P. 6759, 45067 Orleans Cedex 2, France. 2. INRA, Unité de Zoologie Forestière, B.P. 20619, 45166 Olivet Cedex, France.
The level of the critical threshold of attack density above which trees are overcome is a measure of tree resistance to a given bark beetle population. It is also a way to compare the aggressiveness of different bark beetle populations.
Usually, Ips sexdentatus is not a very dangerous bark beetle because its populations rarely reach high levels, and it reproduces on wind blown or weakened trees or on trees attacked by other bark beetle species. Following the storms of December 1999 in south-western France, however, its populations increased considerably during 2000, which resulted, in 2001, in several deadly attacks on maritime pine (Pinus pinaster) trees. The present study was conducted at this occasion to measure the critical threshold of attack density by this insect and its variations. Four pine forests were considered with 2 plots in each. During summer 2001 in each plot, 15 recently killed trees and 15 neighboring surviving trees were harvested. The density and the distribution of attacks on the bole were determined; the gallery characteristics and beetle status were described on each tree. Transversal bole sections were used to calculate the proportion of damage sapwood and productivity indexes. Surprisingly, the critical threshold of attack density by I.
sexdentatus was extremely low and varied between 100 and 150 attacks / m² depending on plots. The distribution of attacks and the beetle sex-ratio differed between the killed and the surviving trees. Results are discussed in relation to plots characteristics, trees status, beetle population levels and beetle attack behavior. forests were considered with 2 plots in each. During summer 2001 in each plot, 15 recently killed trees and 15 neighboring surviving trees were harvested. The density and the distribution of attacks on the bole were determined; the gallery characteristics and beetle status were described on each tree. Transversal bole sections were used to calculate the proportion of damage sapwood and productivity indexes. Surprisingly, the critical threshold of attack density by I. sexdentatus was extremely low and varied between 100 and 150 attacks / m² depending on plots. The distribution of attacks and the beetle sex-ratio differed between the killed and the surviving trees. Results are discussed in relation to plots characteristics, trees status, beetle population levels and beetle attack behavior.
