Balsam Woolly AdelgidAdelges piceae

Presented by: Allison Kanoti

Balsam Woolly Adelgid

• Readinghttp://www.fs.fed.us/r6/nr/fid/fidls/

fidl118.htm

Introduction

• Forest Management: Natural Regeneration

• Tree Adaptations: Refer to SBW notes

IntroductionBalsam Woolly Adelgid

• Introduced from Europe in early 1900’s

• Susceptible Species: – True firs (Abies sp.) in North America

Tree Symptoms

• 2 general types of infestation– Crown infestation– Stem infestation

Tree Symptoms: Crown Infestation

Gout Phase• swollen branch

nodes• stunted

terminal growth• Needle

Mortality• Bud

Suppression Photo: Robert L. Anderson, USDA Forest Servicewww.forestryimages.org

Crown thinning and Mortality•abnormal crown shape •prone to breakage

Crown Infestation (Cont’d)

Tree Symptoms-stem infestation

Trunk Phase– rotholz (rot=red, holz=wood)

• Red-colored wood

– Purple patches beneath bark– Broken, blocky bark

Diseased Functions

• Tissues initially affected– Needles: mortality– Buds: suppression– Sapwood: uncontrolled, abnormal growth,

poor water conduction

• Impact on tree– crown deformity– dieback– predisposition to windthrow and root disease– death

Diseased Functions

• Impact on Forest– dependent on

climate, forest composition, site

– loss of dominant and co-dominant fir component

– change in species composition and age structure

Source: Greenbank, D.O. 1970. Climate and ecology of the balsam woolly aphid. Can. Ent. 102: 546-578.

Impact on Forest Maritime vs. Continental N.B.

Infestation Pattern

All trees crown and stem infestationsCrown infestations persist w/ new growth

Small, isolated patchesStem infestations on lower boleCrown infestations checked by cold winters

Characteristic Maritime Continental

Tree MortalityMost overstory trees killed or have dead tops

Some large diameter trees killed by stem infestationLow tree mortality

Regeneration Some severely gouted and killed

Regeneration by stem infested trees gouted

Diseased Functions:Impact on Forest

“BALSAM WOOLY ADELGID INFESTATION SALVAGE HARVEST. . .”

Primary Stress Agent

Balsam Woolly Adelgid -- Adelges piceae– Introduced from Europe ca. 1900 on

nursery stock to Maine and Nova Scotia

– On native silver fir does not cause significant damage

– North American host trees: Abies spp.

Photo: USDA Forest Service - Ashville Archives www.forestryimages.org

Pathogen

Signs• Eggs--up to 248 yellow eggs laid in waxy

wool-like extrusions• Larvae--3 larval instars• Adult-- approximately .8 mm long, covered in

waxy wool-like material

Photo:Scott Tunnock, USDA Forest Service, www.forestryimages.org

Photo: Jerald E. Dewey, USDA Forest Service, www.forestryimages.org

Environment

Host: True firs• balsam and Fraser in the east; sub-alpine,

Pacific silver and grand in the west

Native range of balsam fir (from silvics)

Environment

Distribution of Balsam Woolly AdelgidFrom BWA FIDL 1970

East CoastWest to east prevailing winds

limit inland spread

Environment

Moderate winters – Do not survive below -

30º F– Snow and tree

structures afford some protection from cold

Predisposing FactorsTree Adaptations

Introduced Pest North American firs highly

susceptible Site

Productive– Washington State, Pacific silver fir– Johnson et al. 1963

Well drained to dry– Newfoundland– Page 1975

Poorly drained– Maine– Brower 1947

Predisposing FactorsTree Adaptations

Age Related Factors – Initial infestations on larger trees

• Taller• Deeper Crowns • Larger Diameter

– More likely to have stem infestations– Ideal size around 30-40 years old

– Rough barked trees more susceptible (more protected locations)

– Younger, denser stands less susceptible

Predisposing FactorsDegree of Stress

Life Cycle Components Impacting Degree of Stress

• Eggs:average 100 eggs/female 1st gen (50, 2nd gen), some dispersal

• Larvae: Crawlers: mobile stage, dispersal, overwintering

• Adults: High reproductive capacity– Reproduction: parthenogenetic, no males

necessary, no need for mate finding or successful mating

• Multivoltinism

Predisposing Factors: Degree of Stress

Life Cycle (Maine: 2 generations/year)

Overwintering Neosistens

2nd, 3rd instars and adult

Eggs(June)

Break dormancy

Late April, early May

1st Instar(Crawler)

NeosistensHatch w/in several days

No molt

2nd, 3rd instars, adult*, eggs, 1st instar (crawler)

*2nd generation adults abundant late Sept; egg laying thru Mid-Nov.

From: F.P. Hain, 1988 in A.A. Berryman

Predisposing Factors: Degree of Stress

Mechanism of Disruption• Stem Infestation

– change in water transport structures• development of rotholz

– Reaction to chemicals in the insects’ saliva– Thick walled cells, wide rings– Similar to compression wood/heartwood

» poor water conduction

– physiological drought

Predisposing Factors: Degree of Stress

Mechanism of Disruption

Crown Infestation– change in wood

structure (rotholz)– old needles not

replaced– buds inhibited– loss of

photosynthesizing capacity

– gradual starvation

Predisposing Factors: Degree of Stress

Population ControlsWeather

• Early or late freezing temperature • 100% mortality of overwintering stage at -

30ºF, – NB study, ~40% died w/ low T of -22 º F (~80%

after 5 days of -22 ºF)– All other life stages die w/ prolonged temps <32

ºF, killed instantly @ -5 ºF– Cold winters with little snow cover

• Warmer climates see more generations/yr.

Predisposing Factors: Degree of Stress

Population ControlsNative Predatory Invertebrates/Introduced Predators

• Native natural enemies– Predatory mites– Lacewings (occasional)– Plant bugs (Mirids)– Coccinellids– Syrphids

• Most important natural enemy• Success limited by high level of parasitism

• Introduced biological control– 3 Coleoptera– 3 Diptera

http://www.rutkies.de/kaefer/Aphidecta%20obliterata%20-%20Gebirgsmarienkaefer%2001.html

http://photo.dipterologic.com/data/media/1/skuznetzov_syrphus_torvus_DSC072345.jpg

Predisposing Factors: Degree of Stress

Population ControlsNative Predatory Invertebrates/Introduced Predators

Issues• Generalist predators• Univoltine predators, multivoltine target• Do not feed on important life stages• Controls dependent on high adelgid populations• Cold tolerance of introduced controls• Introduced predators all adapted to feeding on stem infestations

Ideal• Specialist Predator

– Capable of surviving on low densities (and keeping densities low)– Capable of responding through increased fecundity or increased feeding

rate to growth of prey populations– Capable of active searching and feeding

• In diverse habitats (stem and twig) • On several life stages (esp. egg crawler)

• Parasitoid (no known on Adelginae)

http://cedarcreek.umn.edu/insects/album/029083009ap.html

Predisposing Factors: Degree of Stress

Population Controls

• Food availability and quality– After several years of infestation, changes

in the bark structure can make individual trees temporarily unsuitable

• Leads to decreased adelgid population• As cracks form, parenchyma is near surface

– Again suitable for adelgid– Possible for insects to build up from low level

populations on understory fir

Inciting Factors

• Arrival of crawler on suitable feeding site

• Insertion of stylet and change to neosistens (rotholz develops at this stage regardless of further survival of the insect)

Contributing Factors

• Drought• Ice and wind damage

– irregular crown shape contributes to predisposition to damage

• Fungal Infection– root rots (which further

predispose to windthrow)

Questions?

Your Questions:

Based on your knowledge of the balsam woolly adelgid and of balsam fir :

1. describe preemptive control measures.

2. Describe reactive control options

Justify your answers with supporting biological and ecological

characteristics of the species