Recent Progress in Researches Recent Progress in Researches in Japanese Oak Wilt in Japanin Japanese Oak Wilt in Japan

Naoto KAMATANaoto KAMATA

Laboratory of EcologyLaboratory of EcologyGraduate School of Natural Science and TechnologyGraduate School of Natural Science and TechnologyKanazawa UniversityKanazawa University

kamatan@kenroku.kanazawakamatan@kenroku.kanazawa--u.ac.jpu.ac.jp

2/22

JOW occurred occasionally after 1930s.JOW occurred occasionally after 1930s.JOW has been prevalent since late 1980s: It JOW has been prevalent since late 1980s: It occurred and spread every year.occurred and spread every year.The disease complex consists of the ambrosia beetle, The disease complex consists of the ambrosia beetle, Platypus Platypus quercivorusquercivorus ((MurayamaMurayama) and the ) and the AscomyceteAscomycete fungus fungus RaffaeleaRaffaelea quercivoraquercivora that coexist that coexist in a symbiotic relationship.in a symbiotic relationship.This disease is widely recognized as the only This disease is widely recognized as the only example of an ambrosial fungus vectored by an example of an ambrosial fungus vectored by an ambrosia beetle that kills vigorous trees.ambrosia beetle that kills vigorous trees.

04 AUG 2001Mt. Kariyasu, Ishikawa, Japan04 AUG 200104 AUG 2001Mt. Mt. KariyasuKariyasu, Ishikawa, Japan, Ishikawa, Japan

Oak Mortality Caused by JOWOak Mortality Caused by JOW

3/22

Frass coming out from the trunk surface of a deciduous oak. (July, 2000. Mt. Kariyasu, Ishikawa, Japan)

4/22

5/22

5mm

Platypus Platypus quercivorusquercivorus ((MurayamaMurayama))

Female carries spores of ambrosia fungiFemale carries spores of ambrosia fungi

MF

Aduts

MycangiaMycangia

Raffaelea quercivoraPhoto by Shin-ichiro Ito

6/22

Inoculation Experiment of Inoculation Experiment of R. R. quercivoraquercivora to Oak Treesto Oak Trees

Photos by Shin-ichiro Ito, Mie University

7/22

pupal cell horizontal gallery

entry hole

After Kinuura (1994)

Mechanism of JOWMechanism of JOW

Insect attackInsect attackDevelopment of the Development of the fungusfungusNecrosisNecrosisNecrosis

InfestedInfested

UninfestedUninfested

Water conductance Water conductance will stopwill stop

Heartwood

Necrosis

BarkCambium

Sapwood

Tree Mortality

8/22

Mortality of Trees Newly Mortality of Trees Newly Attacked by Attacked by P. P. quercivorusquercivorus

Other reportsOther reportsMortality is higher in Qc than in Qs (Mortality is higher in Qc than in Qs (NishigakiNishigaki et al. 1998, et al. 1998, Inoue et al. 1998).Inoue et al. 1998).The mortality of evergreen oaks are generally low (<10%) The mortality of evergreen oaks are generally low (<10%) (e.g. (e.g. SueyoshiSueyoshi 1990).1990).

Q. crispula is most susceptible to R. quercivora.

0

10

20

30

40

50

Qc Qs Qa Qsa Cc

19981999

Mor

talit

y

%

Tree Species

Qc: Quercus crispulaQs: Quercus serrataQa: Quercus acutaQsa: Quercus salicinaCc: Castanopsis cuspidata

9/22

Among Tree Species Difference in Reproductive Among Tree Species Difference in Reproductive Success and Tree Preference of Success and Tree Preference of P. P. quercivorusquercivorus

Q. Q. crispulacrispula is the is the most suitable most suitable living host for living host for reproduction of reproduction of P. P. quercivorusquercivorusQ. Q. crispulacrispula was was preferred least by preferred least by P. P. quercivorusquercivorus..

Year

0

20

40

60

80

100

1998 1999 20001997

Q. serrata

Q. crispula

C. cuspidata

Q. acuta

All Fagaceae trees

%Trees in

fested b

y P. quercivorus

Q. acutaQ. serrata

Q. crispulaC. cuspidata

01234

n= 222n= 189

n= 356

n= 310

a

b c b

Rep

rod

uctio

n rate

10/22

CoevolutionCoevolution of Treeof Tree--FungusFungus--InsectInsectQ. Q. crispulacrispula isis

most susceptible to R. quercivora.the most suitable living the most suitable living host for reproduction host for reproduction of of P. P. quercivorusquercivorus..preferred least by preferred least by P. P. quercivorusquercivorus..

Distribution of P. quercivorus

Other oaks resistant to the Other oaks resistant to the fungus evolved under a fungus evolved under a stable relationship between stable relationship between tree, fungus and beetle tree, fungus and beetle during a long evolutionary during a long evolutionary process. process. Q. Q. crispulacrispula was probably was probably not part of this not part of this coevolutioncoevolution..

Q. salicinaQ. crispula Q. serrata Castaneacrenata

Q. acuta Castanopsiscuspidata

JOW & Climate Change JOW & Climate Change

Year

Dif

fere

nce

fro

m t

he

no

rmal

(o C

)

JOW & Climate Change JOW & Climate Change

Warm climate since the late 1980s was the likely Warm climate since the late 1980s was the likely cause of expansion of JOW in Japan, which made cause of expansion of JOW in Japan, which made the fateful encounter of the fateful encounter of P. P. quercivorusquercivorus with with Q. Q. crispulacrispula by pushing the distribution of by pushing the distribution of P. P. quercivorusquercivorusto a more northern and higher place.to a more northern and higher place.

Warming

North

South

Vertical distribution of Q. crispula

Vertical distribution of JOW incidence

Overlapping!

13/22

Spreading PatternSpreading Pattern

<1980

1980s

1990s

After 1980s, JOW spread concentrically, which is a typical pattern of range expansion of invasive species.Four foci, indicating that there was at least 4 times of independent introductions.

Until 1980, incidence of JOW was restricted to small numbers of locations.

14/22

Spreading Rate at a Regional ScaleSpreading Rate at a Regional Scale

Ishikawa

Fukui

Shiga

Yamagata

Niigata

Tottori HyogoKyoto

(Ito & Yamada1998)

1.9 km/yr

1.9 km/yr

2.3 km/yr

3.1 km/yr

19971998

20002002

60 km=5 years

12 km/yr

Ishikawa Pref.Toyama Pref.

Insect Flight and Winds Insect Flight and Winds

0

50

200

0

50

150

wind

Male Female

Rayleightestp<0.001

V-testp<0.001

Rayleightestp<0.001

V-testp < 0.001

Wind-vane trap

P. P. quercivorusquercivorus adults tend to move to downwind.adults tend to move to downwind.

windinsects insects

16/22

Spreading Rate and WindsSpreading Rate and Winds

JOW spread faster to eastward because JOW spread faster to eastward because most beetles fly most beetles fly downwindsdownwinds and because and because west wind is prevailing.west wind is prevailing.

0 50 100km0 50 100km

?

2.5 km/yr

Wind

0.3 km/yr

N

S

W E

Spreading Pattern of JOW at a Landscape Level Spreading Pattern of JOW at a Landscape Level

? ? ? ? ?

0 250 500 m0 250 500 m0 250 500m

19971998

19992000

18/22

Distance between new Distance between new occurrence of JOW and the occurrence of JOW and the nearest trees that had been nearest trees that had been killed in the past killed in the past

0

200

400

600

800

1000

010

020

030

040

050

060

070

080

090

010

00

Distance (m)

Fre

qu

ency

distance of damage in 1998 from damage in 1997

0100200300400500600700800900

1000

010

020

030

040

050

060

070

080

090

010

00

Distance (m)

Fre

qu

ency

distance of 99 damage from 97 damage

0200400600800

100012001400160018002000

010

020

030

040

050

060

070

080

090

010

00

Distance (m)

Fre

qu

ency

distance of 00 damage from 97 damage

Two peaks1. <100m: attacking the neighbor

trees2. 300-600m: attacking trees after

middle range of dispersals

1997? 1998

1997? 1999

1997? 2000

19/22

Combination of dispersals at three Combination of dispersals at three different scales different scales ––Stratified diffusionStratified diffusion--

LongLong--distance distance dispersal (by dispersal (by winds?)(kilo meters)winds?)(kilo meters)MiddleMiddle--range range

dispersion (hundreds dispersion (hundreds meters)meters)Attack to Attack to

neighboring treesneighboring trees

20/22

Light Condition and Light Condition and Distribution of Flying Distribution of Flying AdultsAdults

Adults are positively Adults are positively phototacticphototactic..Many adults were Many adults were caught near a road.caught near a road.

Many adults were Many adults were caught around forest caught around forest gaps.gaps.0

50100150200250

? ? ? ?050

100150200250

road

UP

No. Individuals

DOWN

UP

0

40

80

120

4 8 12 16 20 24 32280

40

80

120

4 8 12 16 20 24 3228

GapUnder canopy

1

32

1

32

1

32

gap

Sticky Intercept Trap

Under canopy

Abu

ndan

ce

dark light dark light dark

road gap

21/22

TopographyTopography--SunlightSunlight--JOW IncidenceJOW Incidence

Adult flights mainly occur in the morning.Adult flights mainly occur in the morning.Adults are positively Adults are positively phototacticphototactic. . JOW occurs on eastJOW occurs on east--facing slopes that receive much facing slopes that receive much sunlight in the morning. sunlight in the morning.

0.0%

0.5%

1.0%

1.5%

N

W

S

0.0%

0.5%

1.0%

1.5%

Frequency of Incidence of JOW and slope aspects

Topography and Brightness

(Red indicates JOW incidence)

Influences of infestation history of the Influences of infestation history of the same species on reproductive success same species on reproductive success

of of Platypus Platypus quercivorusquercivorus

0

2

4

6

8 N= 396

N= 313

N= 356

N= 57

1st yr 2nd yr

Q. crispula Q. serrata

1st yr 2nd yr

b

a

*

*

A A

P. quercivorus cannot reproduce on trees that have received the attacks of the same insect species in the previous year.

No.

of n

ew a

dults

per

gal

lery

What happens in trees?What happens in trees?

1st-year gallery 2nd-year gallery

In the second year, adults of P. quercivorusavoids necrosis caused in the previous year

What happens in necrosis?What happens in necrosis?

0

100

200

300

400

500

0 20 40 min.

Abs.

Gallic acid

Ellagic acid

COOH

OHHO

OH

O

O

O

O

HO

HO OH

OH

0.05% wet weight0.05% wet weight

0.001 % wet weight0.001 % wet weight

25/22

Sapwood

Water TanninSolution

Bark

Dipping > 24hrs

Bioassay of tannins using Bioassay of tannins using P. P. quercivoraquercivora adultsadults

Water

TanninSolution

26/22

Low concentrations of GA, EA, and their mixture

High concentrations of GA, EA, and their mixture

Water

TanninSolution

Water

TanninSolution

Re-creation of an avoiding phenomena recognized in the 2nd-year gallery

27/22

P. P. quercivorusquercivorus Adults Avoids Adults Avoids Tannin Acids in SapwoodTannin Acids in Sapwood

B

B

B

B

BB

0

0.1

0.2

0.3

0.4

0.5

-5 -4 -3 -2 -1 0Concentration (% wet weight)

y=-0.1918logx-0.2573R2=0.9641p=0.0005

0.00001 0.0001 0.001 0.01 0.1 1

? ? ?B

B

B

B

BB

0

0.1

0.2

0.3

0.4

0.5

-5 -4 -3 -2 -1 0

y=-0.1918logx-0.2573R2=0.9641p=0.0005

0.00001 0.0001 0.001 0.01 0.1 1

Gallic acid

B

B

B0

0.1

0.2

0.3

0.4

0.5

-2 -1.8 -1.6 -1.4 -1.2 -1Concentration (% wet weight)

y=-1.1955logx-1.8941R2=0.9954p=0.0437

0.01 0.1

B

B

B0

0.1

0.2

0.3

0.4

0.5

-2 -1.8 -1.6 -1.4 -1.2 -1

y=-1.1955logx-1.8941R2=0.9954p=0.0437

0.01 0.1

Ellagic acid

Rat

io m

ales

pen

etra

ted

into

cub

e Gallery constructions Gallery constructions were completely were completely prevented at prevented at concentration of concentration of 0.025% of 0.025% of ellagicellagicacid and 0.05% of acid and 0.05% of gallic acid.gallic acid.

Application I:Application I:Treatment of Bark by Tannin Acids Treatment of Bark by Tannin Acids

Application II:Application II:Injection of Tannin Acids to SapwoodInjection of Tannin Acids to Sapwood

30/22

Searching Chemical Attractants:Searching Chemical Attractants:Pheromones and Pheromones and KairomonesKairomones

31/22

SummarySummary

Japanese oak wilt (JOW) is an apparently Japanese oak wilt (JOW) is an apparently exotic disease complex that has caused exotic disease complex that has caused increasing levels of mass tree mortality in increasing levels of mass tree mortality in Japanese forests. Japanese forests. The disease complex consists of the The disease complex consists of the ambrosia beetle, ambrosia beetle, Platypus Platypus quercivorusquercivorus((MurayamaMurayama) and the ) and the AscomyceteAscomycete fungus fungus RaffaeleaRaffaelea quercivoraquercivora that coexist in a that coexist in a symbiotic relationship. symbiotic relationship.

32/22

SummarySummary

Warm climate since the late 1980s was the likely Warm climate since the late 1980s was the likely cause of expansion of JOW in Japan, which made cause of expansion of JOW in Japan, which made the fateful encounter of the fateful encounter of P. P. quercivorusquercivorus with with Q. Q. crispulacrispula by pushing the distribution of by pushing the distribution of P. P. quercivorusquercivorus to a more northern and higher place.to a more northern and higher place.

The incidence of JOW are more frequent on eastThe incidence of JOW are more frequent on east--facing slopes. JOW tends to occur besides gaps facing slopes. JOW tends to occur besides gaps and roads. Winds and light conditions are likely and roads. Winds and light conditions are likely factor influencing the incidence and spreads of factor influencing the incidence and spreads of JOW. JOW.

33/22

SummarySummary

Tannin acids seems useful tools to prevent Tannin acids seems useful tools to prevent P. P. quercivorusquercivorus from tunneling.from tunneling.

There are some evidences for existence of There are some evidences for existence of aggregative pheromone in aggregative pheromone in P. P. quercivorusquercivorusbut not yet detected.but not yet detected.