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  • L. C. Wright (a1), A. A. Berryman (a1) and B. E. Wickman (a1)

Fir engraver and Douglas-fir beetle numbers were monitored during and after an outbreak of the Douglas-fir tussock moth. The population behavior of the two species of bark beetles was similar. Number of emerged offspring/female was highest during the years of defoliation and declined afterward. Total number of beetle attacks peaked 1 to 2 years after defoliation ended and then declined. During and 1 year after defoliation, beetles generally infested trees that had greater than 90% defoliation. After this time infestations were not as strongly associated with heavily defoliated trees. Life tables were constructed for beetles within trees and for beetles per area of forest land. Key mortality factors acting on beetles within trees occurred during the larval and pupal stages. Mortality during adult dispersal was a key factor when beetle density per area of land was considered. Although beetle offspring emerging per dm2 of bark surface was relatively low in defoliated trees, defoliation appeared to reduce host resistance which enabled beetles to successfully attack at lower densities, reducing intraspecific competition, and resulting in increased emergence of offspring/female parent.


Le scolyte Scolytus ventralis et le dendroctone du Douglas, Dendroctonus pseudotsugae ont été suivis pendant et après une infestation de la chenille à houppes du Douglas. L'évolution des populations des deux coléoptères s'est avérée similaire. Le nombre de progénitures/femelle était maximal pendant les années de défoliaison et a baissé par la suite. Le nombre total d'attaques a atteint son sommet un à deux ans après l'arrêt de la défoliaison et a chuté ensuite. Pendant la défoliaison et jusqu'à un an après, les coléoptères ont généralement infesté des arbres défoliés à plus de 90%. Par après, les infestations n'étaient pas aussi clairement associées aux arbres sévèrement défoliés. Des tables de survie ont été préparées sur la base des nombres de coléoptères par arbre et par unité de surface du couvert forestier. Les facteurs-clés expliquant la mortalité intra-arbre ont agi pendant les stades larvaires et pupal. La mortalité durant la dispersion par le vol est apparue comme un facteur-clé lorsque la densité des coléoptères par unité de surface était considérée. Bien que le nombre de progénitures émergées par dm2 de surface de l'écorce était relativement basse pour les arbres défoliés, la défoliaison a semblé réduire la résistance de l'hôte ce qui a favorisé l'attaque à basse densité, réduisant ainsi la compétition intraspécifique et causant une augmentation du nombre de progénitures émergeant par femelle.

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A. A. Berryman 1968. Distributions of Scolytus ventralis attacks, emergence, and parasites in grand fir. Can. Ent. 100: 5768.

A. A. Berryman 1973. Population dynamics of the fir engraver, Scolytus ventralis (Coleoptera: Scolytidae). I. Analysis of population behavior and survival from 1964 to 1971. Can. Ent. 105: 14651488.

A. A. Berryman 1974. Dynamics of bark beetle populations: Towards a general productivity model. Environ. Ent. 3: 579585.

A. A. Berryman and M. Ashraf . 1970. Effects of Abies grandis resin on the attack behavior and brood survival of Scolytus ventralis (Coleoptera: Scolytidae). Can. Ent. 102: 12291236.

A. A. Berryman and L. V. Pienaar . 1973. Simulation of intraspecific competition and survival of Scolytus ventralis broods (Coleoptera: Scolytidae). Environ. Ent. 2: 447459.

M. M. Furniss 1962. Infestation patterns of Douglas-fir beetle in standing and windthrown trees in southern Idaho. J. econ. Ent. 55: 486491.

H. D. Hertert , D. L. Miller , and A. D. Partridge , 1975. Interaction of bark beetles (Coleoptera: Scolytidae) and root-rot pathogens in grand fir in northern Idaho. Can. Ent. 107: 899904.

N. E. Johnson 1967. The influence of temperature and moisture on the overwintering mortality of the Douglas-fir beetle, Dendroctonus pseudotsugae, in western Washington (Coleoptera: Scolytidae). Ann. ent. Soc. Am. 60: 199204.

R. R. Lejeune , L. H. McMullen , and M. D. Atkins . 1961. The influence of logging on Douglas-fir beetle populations. For. Chron. 37: 308314.

H. Podoler and D. Rogers . 1975. A new method for the identification of key factors from life-table data. J. Anim. Ecol. 44: 85114.

J. A. Rudinsky 1966. Host selection and invasion by the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, in coastal Douglas-fir forests. Can. Ent. 98: 98111.

W. L. Webb and J. J. Karchesy . 1977. Starch content of Douglas-fir defoliated by the tussock moth. Can. J. For. Res. 7: 186188.

L. C. Wright , A. A. Berryman , and S. Gurusiddaiah . 1979. Host resistance to the fir engraver beetle, Scolytus ventralis (Coleoptera: Scolytidae). 4. Effect of defoliation on wound monoterpene and inner bark carbohydrate concentrations. Can. Ent. 111: 12551262.

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The Canadian Entomologist
  • ISSN: 0008-347X
  • EISSN: 1918-3240
  • URL: /core/journals/canadian-entomologist
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