Douglas-fir beetle brood production was studied on Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees defoliated by the western spruce budworm between 1983 and 1985. Tallies were made of the number of attacks, total length and number of egg galleries, number of eggs deposited, number of larval tunnels, number of pupal chambers, and number of emerging beetles (per female and per unit area). Data analysis showed no significant differences among the three years studied. The number of emerging beetles per female parent was 0.59, and emergence per 90 cm2 was 2.32 beetles. Egg, larval, and pupal survivals were 47.5%, 30.0%, and 15.5%, respectively

Fredricks, S E

Jenkins, M J

English

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Utah State University DigitalCommons@USU The Bark Beetles, Fuels, and Fire Bibliography Quinney Natural Resources Research Library, S.J. and Jessie E. 1988 Douglas-Fir Beetle (Dendroctonus pseudotsugae Hopkins, Coleoptera : Scolytidae) Brood Production on Douglas-Fir Defoliated by Western Spruce Budworm (Choristoneura occidentalis Freeman, Lepidoptera : Tortricidae) in Logan Canyon, Utah S E. Fredricks M J. Jenkins Follow this and additional works at: https://digitalcommons.usu.edu/barkbeetles  Part of the Ecology and Evolutionary Biology Commons, Entomology Commons, Forest Biology Commons, Forest Management Commons, and the Wood Science and Pulp, Paper Technology Commons Recommended Citation Fredricks, S. and Jenkins, J. (1988). Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins, Coleoptera : Scolytidae) brood production on Douglas-fir defoliated by western spruce budworm (Choristoneura occidentalis Freeman, Lepidoptera : Tortricidae) in Logan Canyon, Utah. Great Basin Naturalist, 48(3): 334-347. This Article is brought to you for free and open access by the Quinney Natural Resources Research Library, S.J. and Jessie E. at DigitalCommons@USU. It has been accepted for inclusion in The Bark Beetles, Fuels, and Fire Bibliography by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu. Great Basin NaturalistVolume 48 | Number 3 Article 57-31-1988Douglas-fir beetle (Dendroctonus pseudotsugaeHopkins, Coleoptera: Scolytidae) broodproduction on Douglas-fir defoliated by westernspruce budworm (Choristoneura occidentalisFreeman, Lepidoptera: Tortricidae) in LoganCanyon, UtahS. E. FredericksUtah State UniversityM. J. JenkinsUtah State UniversityFollow this and additional works at: https://scholarsarchive.byu.edu/gbnThis Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has beenaccepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contactscholarsarchive@byu.edu, ellen_amatangelo@byu.edu.Recommended CitationFredericks, S. E. and Jenkins, M. J. (1988) "Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins, Coleoptera: Scolytidae) broodproduction on Douglas-fir defoliated by western spruce budworm (Choristoneura occidentalis Freeman, Lepidoptera: Tortricidae) inLogan Canyon, Utah," Great Basin Naturalist: Vol. 48 : No. 3 , Article 5.Available at: https://scholarsarchive.byu.edu/gbn/vol48/iss3/5DOUGLAS-FIR BEETLE {DENDROCTONUS PSEUDOTSUGAE HOPKINS,COLEOPTERA: SCOLYTIDAE) BROOD PRODUCTION ON DOUGLAS-FIRDEFOLIATED BY WESTERN SPRUCE BUDWORM(CHORISTONEURA OCCIDENTALIS FREEMAN, LEPIDOPTERA:TORTRICIDAE) IN LOGAN CANYON, UTAHS. E. Fredericks' and M. J. JenkinsAbstract—Douglas-fir beetle brood production was studied on Douglas-fir {Pseudotsuga menziesii [Mirb] Franco)trees defoliated by the western spruce budworm between 1983 and 1985. Tallies were made of the number of attacks,total length and number of egg galleries, number of eggs deposited, number of larval tunnels, number of pupalchambers, and number of emerging beetles (per female and per unit area). Data analysis showed no significantdifferences among the three years studied. The number of emerging beetles per female parent was 0.59, andemergence per 90 cm^ was 2.32 beetles. Egg, larval, and pupal survivals were 47.5%, 30.0%, and 15.5%, respectively.The Douglas-fir beetle {Dendroctonuspseudotsugae Hopkins, Coleoptera: Scolyti-dae) attacks Douglas-fir (Pseudotsuga rnen-ziesii [Mirb.] Franco) trees throughout itsrange in western North America. The beetleis normally considered a secondary pest, at-tacking trees that are windthrown, diseased,or stressed by other environmental factors.Damage from logging operations, drought,wildfire, and snow breakage is commonly as-sociated with Douglas-fir beetle epidemics(Bedard 1950, Furniss and Carolin 1977,Coulson and Witter 1984). Stress created bytree defoliation can also contribute to in-creased beetle populations (Wright et al.1984) and may be a factor in the current beetleoutbreak in Logan Canyon, Utah. Endemiclevels of Douglas-fir beetles are commonlyfound in felled and damaged trees (Bedard1950, Furniss et al. 1979), and studies on hostselection indicate the beetle prefers freshlyfelled trees (McMullen and Atkins 1962).When such host material is abundant, popula-tions can build to epidemic levels so thebeetle may be able to successfully attack rela-tively healthy trees (Bedard 1950, Furniss etal. 1979). For a discussion on the mechanismsof beetle host colonization and the role ofsemio-chemicals .see Wood (1982).Douglas-fir beetle outbreaks decline due tolack of suitable host material, greater hostresistance (Furniss et al. 1979), and increasedintraspecific competition (McMullen and At-kins 1961, Berryman et al. 1973, Wright et al.1984). Other biotic agents, such as predators,parasites, and pathogens, are important inpopulation collapse (Furniss et al. 1979). Peri-odic Douglas-fir beetle outbreaks in the Inter-mountain West and the northern RockyMountain areas generally last from three to sixyears (Furniss and McGregor 1979, Wright etal. 1984).The western spruce budworm (Choris-toneura occidentalis Freeman, Lepidoptera:Tortricidae) defoliates current year's growthand may feed on previous years' needles aswell. Western spruce budworm outbreaks inwestern North America generally lack a typi-cal pattern and occur at irregular intervals,thus making it difficult to predict future out-breaks (Brookes et al. 1985). Stand conditionsfavorable to the western spruce budworm re-sult, in part, from past fire suppression andselective cutting practices that have producedmultistoried stands with an abundance ofshade-tolerant species favored by the westernspruce budworm (Coulson and Witter 1984,Brookes et al. 1985).This study was undertaken to obtain a bet-ter understanding of Douglas-fir beetle out-breaks in northeastern Utah. This paper de-•scribos brood production during the peak ofDouglas-fir beetle activity to determine maxi-mum attack density, optimiun brood produc-tion, and beetle emergence (per unit area andper female) at peak production levels. Results' Department of Fort-st Re.soiirces, Utah Stale Universit>', Logan, Utah H4322-.521.';.348July 1988 Fredericks, Jenkins: Douglas-fir Beetle 349Table L Douglas-fir beetle densities and brood development over a three-year period of defoliation by westernspruce budworm. Values based on 90-cm^ sample.350 Great Basin Naturalist Vol. 48, No. 3McMullen and Atkins (1961) suggested thatbrood production and survival of the Douglas-fir beetle are related to attack density. Theyalso found that egg gallery length and eggs perunit gallery length may be influenced by at-tack density, and there was an inverse rela-tionship between average gallery length andattack density. However, Schmitz and Rudin-sky (1968) in similar studies did not find acorrelation between average gallery lengthand attack density.In our study there were 3.97 attacks per 90cm^, population levels typical of an outbreak(McMullen and Atkins 1961, Berryman 1974).Our results make it possible to define aDouglas-fir beetle outbreak based on attackdensity. A low beetle population will have amean attack density of0-2 attacks per 90 cm,a moderate population (optimum for broodproduction) will have 3-5 attacks per 90 cm,and a high beetle population will have morethan 5 attacks per 90 cm^. Studies also suggestthat heavily defoliated trees may not be themost optimal host for beetle brood productiondue to loss of nutrients (Wright et al. 1979).Others have found that optimum bark beetlesurvival occurs at medium attack densitiesand that survival at high attack densities islimited by intraspecific competition and hostavailability/resistance (McMullen and Atkins1961, Berryman and Pienaar 1973, Berryman1974, Fumiss et al. 1979). In our study thebeetle population reached a peak and was sta-ble at that level for the three years sampled.Optimum attack density occurred at 3-5 at-tacks per 90 cm^ in this study. Given the factthat the beetle epidemic was in its fourth yearand that Douglas-fir beetle epidemics gener-ally last from three to six years, the beetleoutbreak in Logan Canyon probably will notbe sustained much longer. Population levelswill most likely decrease markedly withinthe next year as a result of a combination ofgreater host resistance/lack of host materialand resultant intraspecific competition.According to Wright et al. (1984), emer-gence per female is more indicative of in-traspecific competition, while emergence perunit area generally indicates the degree ofhost suitability. In the present study emerg-ing beetles per female and per unit area havepeaked during the same period. These resultsdiffer from those of Wright et al. (1984), whofound that Douglas-fir beetle emergence perfemale was highest in years of Douglas-fir tus-sock moth (Orgyia pseudotsugata McDun-nough, Lepidoptera: Lymantriidae) defolia-tion, while emergence per unit area peakedthree years after defoliation ceased.In the study by Wright et al. (1984) thebeetles generally attacked trees that were de-foliated 90% or greater by the tussock moth.Heavy defoliation lasted only one year, withmany trees recovering within two years afterdefoliation ceased. They also found thatbeetle attacks were less strongly associatedwith defoliation intensity in later years. In thepresent study defoliation intensity by thebudworm was classified as light to moderate(Anhold and Holland 1983) over a period oftwo to three years. Thus, the type and amountof defoliation can be a major factor in beetlebrood production. Wright et al. (1984) sug-gested that heavily defoliated trees may notbe optimal for beetle brood production due toloss of nutrients.Furniss (1962) divided the infested portionof standing trees into three zones. The basalzone extends 2.7-4.6 m from the base of thetree. The middle zone, which has the greatestsurvival potential for beetles, extends towithin 1.0-3.0 m of the uppermost infesta-tion. The top zone is above this, but successfiilattacks are rare in this zone. The uppermostarea of infestation in this study did not exceeda height of 12.2 m.Sampling in the basal zone involved use ofastandard 90-cm" bark punch. Population sam-pling by this method avoids the need to fell orclimb trees and provides a (juick method ofevaluating a beetle outbreak.AcknowledgmentsWe thank David Holland of the USDA,Forest Service, Forest Pest Management, In-termountain Region, for continued support ofour work. This is paper number 3511 of theUtah Agricultural Experiment Station.Literature CitedAnmoi.d.J a.andD H Holland 1983. Biological eval-uation of western spruce huciworni on the LoganRanger District Wasatcli-C]ache National Forest,Utah. USDA Forest Ser%ice Pest Management,Ptihl. R4-83-18, Intermountain Region, Ogden,I'tah. 7 pp.Bkdari). W D. 1950. The Douglas-fir beetle. USDACirc. 817. Washington, D.C. 10 pp.July 1988 Fredericks, Jenkins: Douglas-fir Beetle 351Berryman. a. a. 1973. Population dynamics of the firengraver, Scolytus ventralis (Coleoptera: Scolyti-dae). Analysis of population behavior and survivalfrom 1964-1971. Canadian Entomol. 105: 1465-1488.Berryman, A. A , and L. Pienaar. 1973. Simulation ofintraspecific competition and survival of Scolytusventralis broods (Coleoptera: Scolytidae). Envi-ron. Entomol. 2(1): 447-459.1974. Dynamics of bark beetle populations: to-ward a general productivity model. Environ. En-tomol. 3(4): 579-585.Brookes, M H.J J Colbert, R G Mitchell, and R WStark. 1985. Managing trees and stands suscepti-ble to western spruce budworm. USDA ForestService Cooperative State Research Service,Tech. Bull. 1695. Washington, DC.CouLSON, R. N., and J. A. Witter. 1984. Forest entomol-ogy: ecology and management. John Wiley andSons, Inc. , New York. 669 pp.FURNISS, M. M. 1962a. Infestation patterns of theDouglas-fir beetle in standing and windthrowntrees in southern Idaho. J. Econ. Entomol. 55(4);486-491.1962b. A circular punch for cutting samples ofbarkinfested with beetles. Canadian Entomol. 94:959-963.1964. A method to determine progressive mortal-ity during seasonal development ofthe Douglas-firbeetle brood. J. Econ. Entomol. 57(1): 178-181.FuRNiss, M M,M D McGregor. M W Foiles, andA. D Partridge 1979. Chronology and character-istics of a Douglas-fir beetle outbreak in northernIdaho. USDA Forest Service Gen. Tech. Rept.lNT-59. Intermountain Forest and Range Expt.Sta., Ogden, Utah.FuRNiss, M M ,andP W Orr 1978. Douglas-fir beetle.USDA Forest Insect and Disease Leaflet. Wash-ington, DC. 4 pp.FuRNiss, R L,and V M Carolin 1977. Western forestinsects. USDA Forest Service Misc. Publ. 1339.McMullen, L. H.AND M D Atkins 1961. Intraspecificcompetition as a factor in the natural control of theDouglas-fir beetle. For. Sci. 7: 197-203.1962. On the flight and host selection of theDouglas-fir beetle, Dendroctonus pseudotsugaeHopkins (Coleoptera: Scolytidae). Canadian Ento-mol. 94: 1309-1325.SCHMIT^, R F,AND J A RUDINSKY 1968. Effects ofcompetition on survival in western Oregon of theDouglas-fir beetle, Dendroctonus pseudotsugaeHopkins (Coleoptera: Scolytidae). School ofForestry, Oregon State University, Coi-vallis. Re-search Paper 8. 42 pp.WiCKMAN, B. E 1978. Tree mortality and top-kill relatedto defoliation by the Douglas-fir tussock moth inthe Blue Mountains outbreak. USDA Forest Ser-vice Res. Pap. PNW-233. 47 pp.Wood. D L 1982. The role of pheromones, kairomonesand alloniones in host selection and colonizationbehavior of the bark beetle. Ann. Rev. Entomol.27:411-446.Wright, L. C,A A Berryman, and B E. Wickman 1984.Abundance of the fir engraver, Scolytus ventralis,and the Douglas-fir beetle, Dendroctonus pseu-dotsugae, following tree defoliation by theDouglas-fir tussock moth, Orgyia pseudotsugata.Canadian Entomol. 116: 293-305.

Douglas-Fir Beetle (Dendroctonus pseudotsugae Hopkins, Coleoptera : Scolytidae) Brood Production on Douglas-Fir Defoliated by Western Spruce Budworm (Choristoneura occidentalis Freeman, Lepidoptera : Tortricidae) in Logan Canyon, Utah

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Douglas-Fir Beetle (Dendroctonus pseudotsugae Hopkins, Coleoptera : Scolytidae) Brood Production on Douglas-Fir Defoliated by Western Spruce Budworm (Choristoneura occidentalis Freeman, Lepidoptera : Tortricidae) in Logan Canyon, Utah

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