click beetles and pheromones Œ an overvie · 2013. 12. 5. · o o 7-methyloctyl 5-methylhexanoate...

Click beetles and pheromones � anoverview

Miklós Tóth

Plant Protection Institute, HAS, Budapest, Hungary

Wireworms, the larvae of click beetles (Coleoptera: Elateridae) areimportant soil-dwelling polyphagous pests all over the world.

www.naturamediterraneo.com

www.photoshelter.com

Traditional forecast and monitoring involves labour-intensive soilsampling methods,

Photo L. Furlan

and to obtain wireworms from soil samples collected is time-consuming(several days or more). Photo L. Furlan

Pheromone-baited traps are much easier and simpler to use.

However, the pheromonecomposition should be

identified first!

On the picture: the YF trap design specifically developed for pheromone trapping of clickbeetles (Furlan Inform. Fitopat. 10:49. (2004)

Photo M. Tóth

The very first chemical structures elucidated from click beetles (female-produced pheromone) were organic acids

Pheromone structures - first identifications

OH

O

valeric acid (pentanoicacid)

Limonius californicus

Jacobson Science 159:208(1968)

OH

O

caproic acid (hexanoicacid)

Limonius canus

Butler Environ. Entomol. 4:229(1975)

Limonius californicuswww.bugguide.net

Starting from the eighties, a number of geranyl and farnesyl esters wereidentified mainly by scientists from the Soviet Union.

Pheromone structures - geranyl/farnesyl esters

OO

geranyl butyrate[(E)-3,7)-dimethyl-2,6-

octadienyl butyrate]

i.e. A. sputator

Example structures:

O

O

(E,E)-farnesyl acetate[(E)-3,7,11)-trimethyl-2,6,10-

dodecatrienyl acetate]

i.e. A. ustulatus

First report on similar structures from: Oleschenko, 1979, cited in Kamm, Coleopt. Bull. 37:16(1983)

Permutations and combinations of such compounds are present in thepheromones of several Agriotes spp.


4 6 8 10 12 14 16 18 20 22 24 min

IS

IS

IS

IS

IS

obscurus

ustulatus

sordidus

litigiosus

lineatus

brevis

sputator

ger.but.

IS

ger.i-val.ger.oct.

ger.hex. farn.acet.

farn.but.

GC analysis of pheromone gland extracts of Agriotes spp. (after Tóth J. Chem. Ecol.. 28:1641(2002) and Pest Manag. Sci. 59:1 (2003)

Structures for many spp. were reported, however, a great part of thesecompounds showed no behavioral activity.


I

PA

I = compound identified but nobehavioral activity shown

P = compound identified,found attractive

A = synthetic compoundattractive, but not knownwhether present in female

Data from <www.pherobase.com> and my own files

Total: 24 spp.

One reason for this may be thatmost early identifications werebased on direct gland extracts,which may not necessarilyrepresent composition emittedinto the air by the females.


supposedpheromoneglands /reservoirs

ovary

accessory gland

bursa

oviduct

(After Ivaschenko Zool. Zh. 59: 225(1980).

Agriotes sordidus

geranyl hexanoate

E,E-farnesylhexanoate

int. std.

?

glands

volatiles

15 20 25 30 35 40 45 50 50 min

ratio ger:farn =1:1

ratio ger:farn =1:<0.1

In A. sordidus, in gland extracts large amounts of (E,E)-farnesylhexanoate were present, with only traces in volatile collections.

Gland extract vs. volatile collection (example No. 1)

A. sordidusPhoto J. Vuts

Agriotes sordidus

geranyl hexanoate


int. std.

?

glands

volatiles

15 20 25 30 35 40 45 50 50 min

ratio ger:farn =1:1

ratio ger:farn =1:<0.1 av

erag

e ca

tch/

trap

/insp

ectio

n

Total caughtin test:

535beetles

0

10

20

-- 3 30 30 3030 30 30 3 --

geran. hex.E,E-farn. hex.

(mg)

aa

b b b

Eraclea, Italy,1998

(after Tóth M, et al., unpublished)

In field tests on A. sordidus, no influence of the addition of the farnesylcompound could be observed.


Agriotes sordidus

geranyl hexanoate


int. std.

?

glands

volatiles

15 20 25 30 35 40 45 50 50 min

ratio ger:farn =1:1

ratio ger:farn =1:<0.1 av

erag

e ca

tch/

trap

/insp

ectio

n


535beetles

0

10

20

-- 3 30 30 3030 30 30 3 --

geran. hex.E,E-farn. hex.

(mg)

aa

b b b

Eraclea, Italy,1998

(after Tóth M, et al., unpublished)

Consequently, by definition, only geranyl hexanoate can be termed apheromone component in this species.


4 6 8 10 12 14 16 18 20 22 24 min

int. std.

geranyl octanoate

retention region ofgeranyl butyrate

Gland extracts of A. lineatus were dominated by a single very large peakof geranyl octanoate, geranyl butyrate was hardly detectable (ratio of

octanoate:butyrate = 100:<0.01)


geranyl-octanoate

geranyl-butyrate

int.std.

2 4 6 8 10 12 14 16 18 20 22 24 min

(After Vuts J. et al., in preparation)

In volatile collections the butyrate was well visible (ratio ofoctanoate:butyrate = 100:10)


mV

0

5

10

Ger

anyl

buta

noat

e

Ger

anyl

hexa

noat

e

Ger

anyl

octa

noat

e

Ner

ylis

oval

erat

e

E,E

-far

nesy

lac

etat

e

A.li

nea

tus

Rümlang, May 23 - August 14,1997

10 - - - - - 030 - - - - - 2

100 - - - - - 010 1 - - - - 27310 - 1 - - - 210 - - 1 - - 110 - - - 1 - 010 - - - - 1 1

Ger

anio

l


279beetles

In the field the presence of the butyrate was absolutely necessary forattraction.


(After Tóth Pest Manag. Sci. 59:417 (2003)

Ger

anyl

buta

noat

e

Ger

anyl

hexa

noat

e

Ger

anyl

octa

noat

e

Ner

ylis

oval

erat

e

E,E

-far

nesy

lac

etat

e

A.li

nea

tus

Rümlang, May 23 - August 14,1997

10 - - - - - 030 - - - - - 2

100 - - - - - 010 1 - - - - 27310 - 1 - - - 210 - - 1 - - 110 - - - 1 - 010 - - - - 1 1

Ger

anio

l


279beetles

It appears that volatile collections reflect better the true pheromonecomposition of a given species than gland extracts do.


(After Tóth Pest Manag. Sci. 59:417 (2003)

Another reason for inactivity of identified structures may be that in somecases geometrical purity of synthetic compounds is crucial - as

commonly found also in moth pheromones.

Geometrical isomers

O

O

(E,E)-farnesyl acetate

It is well known thatAgriotes ustulatus respondsonly to synthetic (E,E)-farnesyl acetate batcheswhich have >95% (E,E)geometric purity.

Presence of higherpercentages of the otherisomers inhibits catches.

(After Tóth et al., unpublished)

Agriotes ustulatuswww.elateridae.com

A recent report described the first neryl ester (nerol is the geometricalisomer of geraniol) as a pheromone component in Agriotes acuminatus

also suggesting the importance of geometrical isomerism in click beetles.

Geometrical isomers

After Tolasch J. Chem. Ecol. 36:314 (2010)

O

O

OO

geranyl butyrate[(E)-3,7)-dimethyl-2,6-


neryl butyrate[(Z)-3,7)-dimethyl-2,6-


“Good” isomer “Wrong” isomer

The full pheromone composition in A. acuminatus contained also anotherester with an unusual structure, which was necessary for field activity.

Geometrical isomers

After Tolasch J. Chem. Ecol. 36:314 (2010)

O

O

(Z,E)-2,6-dimethyl-2,6-octadien-1,8-diyl

dihexanoate]

neryl butyrate[(Z)-3,7)-dimethyl-2,6-


“Good” isomer second component

OO

O O

Some Melanotus spp. from the far east appear to use dodecenylcompounds (structurally similar to moth pheromones)

Other structures

O

O

O

O

dodecyl acetateMelanotus okinawensis

Tamaki Jpn KokaiTokyo KohoJP 61:12601 (1986)

(E)-9,11-dodecadienyl acetateMelanotus sakishimensis,

M. tamsuyensis

Iwanaga, Appl. Ent. Zool. 35:283 (2000)Yen, Syn. Comm. 28:4561 (1998)

Ami kell)

Other structuresAs new structure, a methyloctanol ester has been identified from the non-

pest Ectinus aterrimus click beetle.

O

O

7-methyloctyl 9-methyldecanoate

Ectinus aterrimus

Tolasch Chemoecology 18:177 (2008)

www.biolib.cz

Ami kell)

Other structuresFour similar esters were recently shown out from E. ferrugineus, an

endangered click beetle.

Tolasch J. Chem. Ecol.33:2156 (2007)

www.nhmus.hu

O

O

7-methyloctyl 5-methylhexanoate

O

O

7-methyloctyloctanoate 7-methyloctyl 7-

methyloctanoate

O

O

O

O

7-methyloctyl(Z)-4-decenoate

Elaterferrugineus

Kairomonal effect:E. ferrugineus also is attracted to thepheromone of its prey, Osmoderma

eremita (Scarabaeidae).

www.nhmus.hu

Elaterferrugineus

Other structures

Osmoderma eremita

www.hvlfoto.cz

O

O

(R)-gamma-decalactone

Svensson J. Chem. Ecol. 30:353 (2004)

At present we have some information on chemical structures in 34 spp.Information on the genus Agriotes predominates.

Pheromone information in click beetle genera

Data from <www.pherobase.com> and my own files

Total: 33 spp.

AgriotesAthousCidnopusEctinusElaterLimoniusMelanotusSynaptus

2

4

6

8

10

12

14

0.5

1

1.5

2

2.5

0 10 30 100 mg

mea

n / t

rap

(+SE

)m

ean

/ tra

p (+

SE)

a b c c

a b bc c

(total caught:709 beetles)


Catches of male and femaleA. sordidus in traps baitedwith different doses of thepheromone (Italy, Veneto,May 1 - 26, 2001, Furlan etal., unpubl.)

Traditionally it was thought that in click beetles only males respond tothe pheromone (as in the case of “classical” sex pheromones).

Females responding to the pheromone

2

4

6

8

10

12

14

0.5

1

1.5

2

2.5

0 10 30 100 mg

mea

n / t

rap

(+SE

)m

ean

/ tra

p (+

SE)

a b c c

a b bc c



However, L. Furlan observed that in traps of A. sordidus baited withsynthetic pheromone, sizeable catches of females (besides large catches

of males) were recorded



2

4

6

8

10

12

14

0.5

1

1.5

2

2.5

0 10 30 100 mg

mea

n / t

rap

(+SE

)m

ean

/ tra

p (+

SE)

a b c c

a b bc c



Female catches also showed a dose response, suggesting that thepheromone showed true attraction in female A. sordidus.



0

2

4

6

8

1 0

1 2

1 4

1 6

BREVbait unbaited

A. brevis

Total caught: 194 beetles

P= 0.0011

Eraclea, Italy, 2000

Mea

n ca

tche

s (+

SE)

pheromonebait

pheromone components:(E,E)-farnesyl butyrate +

geranyl butyrate www.elateridae.com

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

transpbait transpUNBAITED

A. ustulatus

P= 0.0002

pheromone component:(E,E)-farnesyl acetateEraclea, Italy, 2000


0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

mg30 unb(test)

A. sordidus

P= 0.0001

Berton-Greggio, Italy, 2001

pheromone component:geranyl hexanoate


Attraction of females to the respective synthetic pheromone has beenconfirmed in several species, so the case of A. sordidus is not unique.


(after Vuts J. et al., unpublished)

0100200300400500600700800

control

0

50

100

150

200

250

300

350

mea

n no

rmal

ized

res

pons

es (

+SE

)

%

standard

pheromone

(E,E

)-fa

rnes

ylac

etat

e(E

,E)-

farn

esyl

buty

rate

(E,E

)-fa

rnes

ol

gera

niol

gera

nyl

buty

rate

gera

nyl

hexa

noat

ege

rany

lis

oval

erat

ege

rany

loc

tano

ate

gera

nyl

prop

iona

te

air

Agriotessordidus

What is more, female antennae responded well to the pheromone andgave similar response spectra in EAG to that of male antennae.


control

mea

n no

rmal

ized

res

pons

es (

+SE

)

%

standard

pheromone

(E,E

)-fa

rnes

ylac

etat

e(E

,E)-

farn

esyl

buty

rate

(E,E

)-fa

rnes

ol

gera

niol

gera

nyl

buty

rate

gera

nyl

hexa

noat

ege

rany

lis

oval

erat

ege

rany

loc

tano

ate

gera

nyl

prop

iona

te

air

0

50

100

150

200

250

300

350

400

0

5 0

100

150

200

250

300

350

pheromone

This again was true to a number of species, and strongly suggested thatfemales are capable to perceive their respective pheromone components.


Agriotesbrevis


control

mea

n no

rmal

ized

res

pons

es (

+SE

)

%

standard

pheromone

(E,E

)-fa

rnes

ylac

etat

e(E

,E)-

farn

esyl

buty

rate

(E,E

)-fa

rnes

ol

gera

niol

gera

nyl

buty

rate

gera

nyl

hexa

noat

ege

rany

lis

oval

erat

ege

rany

loc

tano

ate

gera

nyl

prop

iona

te

air

0

50

100

150

200

250

300

350

400

0

5 0

100

150

200

250

300

350

pheromone

This brings up the possibility that the pheromones of click beetles arewrongly classified into the “classical” sex pheromone cathegory.


Agriotesbrevis


0

5

1 0

1 5

2 0

2 5

3 0

floral lure

pheromone

white colour

ba


Debrecen, 2008

f(total caught:2532 beetles)

f

Eraclea, 2008

mea

n ca

tch

+SE

c

d

0

5

1 0

1 5

2 0

2 5

3 0 ba

c

In A. ustulatus, a floral lure has been discovered, which attracts females.(White colour as attractive visual cue showed negligible influence)

Sex pheromone vs. aggregation pheromone?

(After Tóth M. et al., in preparation)

0

5

1 0

1 5

2 0

2 5

3 0

floral lure

pheromone

white colour

ba


Debrecen, 2008

f(total caught:2532 beetles)

f

Eraclea, 2008

mea

n ca

tch

+SE

c

d

0

5

1 0

1 5

2 0

2 5

3 0 ba

c

The addition of the pheromone to the floral lure in the same trapincreases catches of females!



ba

Debrecen, 2008(total caught: 6123 beetles)

Eraclea, 2008

mea

n ca

tch

+SE

Most female specimens are caught in traps with both floral ANDpheromonal baits

ba

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

c

0

1 02 0

3 04 0

5 06 0

7 08 0

9 0100

110120

130140

(total caught: 34325 beetles)

pheromone

white colour

f

m

floral lure



ba


Eraclea, 2008

mea

n ca

tch

+SE

A similar phenomenon (that the presence of the pheromone increases theeffect of floral bait on females) is unusual with sex pheromones

ba

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

c

0

1 02 0

3 04 0

5 06 0

7 08 0

9 0100

110120

130140


pheromone

white colour

f

m

floral lure



ba


Eraclea, 2008

mea

n ca

tch

+SE

However, it is frequently reported with aggregation pheromones

ba

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

c

0

1 02 0

3 04 0

5 06 0

7 08 0

9 0100

110120

130140


pheromone

white colour

f

m

floral lure



ba


Eraclea, 2008

mea

n ca

tch

+SE

This again suggests that the pheromone of Agriotes click beetles is not a“classical” sex pheromone

ba

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

c

0

1 02 0

3 04 0

5 06 0

7 08 0

9 0100

110120

130140


pheromone

white colour

f

m

floral lure



Acknowledgements

Scientists cooperating inunpublished results shown:

Bálintné Csonka, É. (Hungary)Francke, W. (Germany)

Furlan, L. (Italy)Subchev, M. (Bulgaria)Szarukán, I. (Hungary)Tolasch, T. (Germany)Toshova, T. (Bulgaria)

Vuts, J. (Hungary)Yatsynin, V.G. (Russia)

click beetles and pheromones Œ an overvie · 2013. 12. 5. · o o 7-methyloctyl 5-methylhexanoate...

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