Pheromones and other semiochemicalsof click beetles - a European

perspective

Miklós Tóth

Plant Protection Institute, Ctr. Agric. Res. Hung.Acad. Sci., Budapest, Hungary

Presented at the ESA Meeting, KnoxvilleTN, USA, 11-14 November 2012.

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 YATLOR FUNNEL (or YF ) trap design specifically developed forpheromone trapping of click beetles (Furlan, Inform. Fitopat. 10:49, 2004)

Photo M. Tóth

The very first chemical structures elucidated from click beetles (female-produced pheromone) came from North America and 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

In Europe, starting from the eighties, a number of geranyl and farnesylesters were identified mainly by scientists from the Soviet Union.

Pheromone structures - first identifications

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 inKamm, Coleopt. Bull. 37:16, 1983)

In the 1990-s we identified new and revisited known (but inactive)pheromones of elaterids (important in Central and Western Europe)

Pheromone structures - my lab’s contribution

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. 59:417, 2003)

A. ustulatusA. obscurusA. sordidusA. litigiosusA. lineatusA. brevisA. sputator

first identification

improved publishedcompositionconfirmed knowncomposition

A. rufi-palpisA. proxi-mus

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

Pheromone structures - my lab’s contribution

supposedpheromoneglands /reservoirs

ovary

accessory gland

bursa

oviduct

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

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:

geranyl-octanoate

geranyl-butyrate

int.std.

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

(After Vuts, Chemoecol. 22:23, 2012)

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

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

mV

0

5

10

volatiles

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

Total caughtin test:

279beetles

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

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

(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

Total caughtin test:

279beetles

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

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

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

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:

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:

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:

Pheromone traps in use in EuropeAs a result of our studies pheromone traps are available for 9 Agriotesspp., (including all of the most important click beetle pests) in Europe.

Agriotes sputator(geranyl butyrate)

April May June July August1 15 30 15 30 15 30 15 30 15

0

2

4

0

20

0

2

0

5

(total caught: 202 beetles)

A. lineatus(geranyl octanoate + ger.butyrate)

(total caught: 1202 beetles)

A. rufipalpis(geranyl hexanoate)

(total caught: 92 beetles)

A. ustulatus(E,E)-farnesyl acetate)

(total caught: 461 beetles)

mea

n ca

tch

/ tra

p (+

S.E

.)

Debrecen, Hungary, 1999

(after Szarukán I. et al., unpublished)

Pheromone traps in use in Europe

gallicus catches

A. sordidus /rufipalpis baitGeranyl hexanoate

1998 - 2006

rufipalpis catches

sordidus catches

Cidnopus pilosus catch

no catch

One application of the traps in recent years was to determine theoccurrence and abundance of the click beetle spp. in Europe.

(after Furlan, IOBC/wprs Bull. 30:19, 2007)

lineatus catches

proximus catches

A. lineatus baitGeranyl octanoate + geranylbutyrate

1998 - 2006

no catch

Pheromone traps in use in EuropeOne application of the traps in recent years was to determine the

occurrence and abundance of the click beetle spp. in Europe.

(after Furlan, IOBC/wprs Bull. 30:19, 2007)

Click beetle pheromone traps capture large numbers of males. In somespecies, however, users reported on the presence of females in the catch!

Females responding to the pheromone

The phenomenon most frequently was reportedin:

A. sordidus and A. brevis –Lorenzo Furlan, Italy

A. ustulatus – István Szarukán,Hungary

On closer scrutiny, beetle catches in pheromone baited traps indeedcontained a sizeable proportion of female beetles in these species!

Females responding to the pheromone

A. brevis

Veneto, Italy, 2001

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

geranyl butyrate www.elateridae.com

A. ustulatuspheromone component:(E,E)-farnesyl acetate

Eraclea, Italy, 2000

Total caught: 114 beetles

A. sordidus

Berton-Greggio, Italy, 2001

pheromone component:geranyl hexanoate

Total caught: 367 beetlesTotal caught: 1173 beetles

Female catches in pheromone baited traps were significantly higher thanin unbaited traps.

Females responding to the pheromone

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

A. ustulatus

P< 0.0001

pheromone component:(E,E)-farnesyl acetateDebrecen, Hungary, 2003

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

Total caught: 42 beetles Total caught: 116 beetles

0

1

2

3

In EAG screenings of synthetic pheromone compounds of click beetles,female antennae showed similar response spectra as male antennae,

responding best to the respective pheromone component.

Females responding to the pheromone

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

air

Agriotessordidus

This suggested that females were capable of detecting their respectivepheromone components.

Females responding to the pheromone

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

air

0

5 0

100

150

200

250

300

350

400

0

5 0

100

150

200

250

300

350

pheromone

Agriotesbrevis

Female catches in pheromone baited traps showed dose dependence,similar to catches of male beetles.

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

(total caught:709 beetles)

(total caught:109 beetles)

A. sordidusBerton-Greggio, Italy, 2001

0

5

10

15

20

25

A. ustulatusCessalto, Italy, 2003

(total caught:1708 beetles)

0

0.5

1

1.5 (total caught:91 beetles)

0 10 30 100 mg

a b bc c

a ab bc c

The demonstrated female attraction to the resp. pheromone brings up thepossibility of developing a trap catching females also.

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

(total caught:709 beetles)

(total caught:109 beetles)

A. sordidusBerton-Greggio, Italy, 2001

0

5

10

15

20

25

A. ustulatusCessalto, Italy, 2003

(total caught:1708 beetles)

0

0.5

1

1.5 (total caught:91 beetles)

0 10 30 100 mg

a b bc c

a ab bc c

In the flower visitor A. ustulatus, a floral lure has been discovered, whichattracts both females and males.

Efficient click beetle traps for both sexes?

0

5

1 0

mea

n / t

rap

(+SE

)

(total caught:935 beetles)

Debrecen, Hungary, 2006

0

5

1 0

(total caught:839 beetles)

Composition of baits:

(E)-anethol

(E)-cinnam-aldehyde

(After Tóth, Acta Phytopath. Hung. 46:235, 2011)

Sex ratio in catch of the 2component floral lure

(total caught 1232 beetles)

= present = absent

0

5

1 0

1 5

2 0

2 5

3 0

floral lure

pheromone

white colour

ba

(total caught:4814 beetles)

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

White colour (a known attractive visual cue for A. ustulatus) showednegligible influence on traps baited with floral or pheromonal lures

Efficient click beetle traps for both sexes?

(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

(total caught:4814 beetles)

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 trapincreased catches of females!

Efficient click beetle traps for both sexes?

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

ba

Debrecen, 2008(total caught: 6123 beetles)

Eraclea, 2008

mea

n ca

tch

+SE

Most female specimens were 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

Efficient click beetle traps for both sexes?

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

ba

Debrecen, 2008(total caught: 6123 beetles)

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

(total caught: 34325 beetles)

pheromone

white colour

f

m

floral lure

Efficient click beetle traps for both sexes?

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

ba

Debrecen, 2008(total caught: 6123 beetles)

Eraclea, 2008

mea

n ca

tch

+SE

The phenomenon is frequently reported with aggregation pheromones, soelaterid pheromones may have to be reclassified.

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

Efficient click beetle traps for both sexes?

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

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)

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