Skip to main content Accessibility help


  • 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.



Hide All
Ashraf, M. and Berryman, A. A.. 1969. Biology of Scolytus ventralis (Coleoptera: Scolytidae) attacking Abies grandis in Northern Idaho. Melanderia 2. 23 pp.
Belyea, R. M. 1952. Death and deterioration of balsam fir weakened by spruce budworm defoliation in Ontario. II. An assessment of the role of associated insect species in the death of severely weakened trees. J. For. 50: 729739.
Berryman, A. A. 1968. Distributions of Scolytus ventralis attacks, emergence, and parasites in grand fir. Can. Ent. 100: 5768.
Berryman, A. A. 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.
Berryman, A. A. 1974. Dynamics of bark beetle populations: Towards a general productivity model. Environ. Ent. 3: 579585.
Berryman, A. A. and Ashraf, M.. 1970. Effects of Abies grandis resin on the attack behavior and brood survival of Scolytus ventralis (Coleoptera: Scolytidae). Can. Ent. 102: 12291236.
Berryman, A. A. and Pienaar, L. V.. 1973. Simulation of intraspecific competition and survival of Scolytus ventralis broods (Coleoptera: Scolytidae). Environ. Ent. 2: 447459.
Berryman, A. A. and Wright, L. C.. 1978. Defoliation, tree condition, and bark beetles. In Brookes, M. H., Stark, R. W., and Campbell, R. W. (Eds.), The Douglas-fir Tussock Moth: A Synthesis. U.S. Dep. Agric. Forest Serv., Tech. Bull. 1585. 331 pp.
Craighead, F. C. 1940. Some effects of artificial defoliation on pine and larch. J. For. 38: 885888.
Evenden, J. C. 1940. Effects of defoliation by the pine butterfly upon ponderosa pine. J. For. 38: 949955.
Ferrell, G. T. 1973. Weather, logging, and tree growth associated with fir engraver attack scars in white fir. U.S. Dep. Agric. Forest Serv. Res. Pap. PSW-92. 11 pp.
Furniss, M. M. 1962. Infestation patterns of Douglas-fir beetle in standing and windthrown trees in southern Idaho. J. econ. Ent. 55: 486491.
Furniss, M. M., McGregor, M. D., Foiles, M. W., and Partridge, A. D.. 1979. Chronology and characteristics of a Douglas-fir beetle outbreak in northern Idaho. U.S. Dep. Agric. Forest Serv., Gen. Tech. Rep. INT-59. 19 pp.
Hertert, H. D., Miller, D. L., and Partridge, A. D., 1975. Interaction of bark beetles (Coleoptera: Scolytidae) and root-rot pathogens in grand fir in northern Idaho. Can. Ent. 107: 899904.
Johnson, N. E. 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.
Lejeune, R. R., McMullen, L. H., and Atkins, M. D.. 1961. The influence of logging on Douglas-fir beetle populations. For. Chron. 37: 308314.
Marsden, M. A., Furniss, M. M., and Kline, L. N.. 1981. Modeling seasonal abundance of Douglas-fir beetle in relation to entomophagous insects and location in trees. U.S. Dep. Agric. Forest Serv., Gen. Tech. Rep. INT-111. 22 pp.
McMullen, L. H. and Atkins, M. D.. 1961. Intraspecific competition as a factor in the natural control of the Douglas-fir beetle. For. Sci. 7: 197203.
Podoler, H. and Rogers, D.. 1975. A new method for the identification of key factors from life-table data. J. Anim. Ecol. 44: 85114.
Rudinsky, J. A. 1966. Host selection and invasion by the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, in coastal Douglas-fir forests. Can. Ent. 98: 98111.
Schmitz, R. F. and Rudinsky, J. A.. 1968. Effect of competition on survival in western Oregon of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae). School For. Oreg. St. Univ. Res. Pap. 8. 42 pp.
Scott, B. A. and Berryman, A. A.. 1971. Laboratory rearing techniques for Scolytus ventralis (Coleoptera: Scolytidae). Wash. agric. Exp. Stn Bull. 741. 9 pp.
Southwood, T. R. E. 1966. Ecological Methods with Particular Reference to the Study of Insect Populations. Methuen, London. 391 pp.
Vité, J. P. and Rudinsky, J. A.. 1957. Contribution toward a study of Douglas-fir beetle development. For. Sci. 3: 156167.
Webb, W. L. and Karchesy, J. J.. 1977. Starch content of Douglas-fir defoliated by the tussock moth. Can. J. For. Res. 7: 186188.
Wickman, B. E. 1958. Mortality of white fir following defoliation by the Douglas-fir tussock moth in California, 1957. U.S. Dep. Agric. Forest Serv. Res. Note 137. 4 pp.
Wickman, B. E. 1963. Mortality and growth reduction of white fir following defoliation by the Douglas-fir tussock moth. U.S. Dep. Agric. Forest Serv., Res. Pap. PSW-7. 15 pp.
Wickman, B. E. 1978. Tree mortality and top-kill related to defoliation by the Douglas-fir tussock moth in the Blue Mountains outbreak. U.S. Dep. Agric. Forest Serv. Res. Pap. PNW-233. 47 pp.
Wright, L. C. and Berryman, A. A.. 1978. Effect of defoliation by the Douglas-fir tussock moth on moisture stress in grand fir and subsequent attack by the fir engraver beetle (Coleoptera: Scolytidae). U.S. Dep. Agric. Forest Serv. Res. Note PNW-323. 14 pp.
Wright, L. C., Berryman, A. A., and Gurusiddaiah, S.. 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.


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


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.