Female-Targeted Semiochemical Baits for the Western Corn Rootworm Diabrotica V

Female-targeted semiochemical baits for the western corn rootworm Diabrotica v. virgifera (Coleoptera: Chrysomelidae)

TÓTH, MIKLÓS1 – VUTS, JÓZSEF1 – SZARUKÁN, ISTVÁN2 – JUHÁSZ, ISTVÁN2 – MANAJLOVICS, FERENC2

1 Plant Protection Institute, HAS, Budapest, Hungary 2 Debrecen University, Ctr. Agric. Res., Debrecen, Hungary In recent years emphasis of semiochemicalKLPflor+ research on the western corn rootworm (WCR) ( Diabrotica v. virgifera KLP felülrŒlLeConte, Coleoptera, Chrysomelidae) shifted towards the development of more female-specific lures.

KLPfero+

KLPflor+ Through identifying volatile compoundsKLPflor+ from maize silk, Hammack et al (J. Chem. Ecol. 27:1373-1390, 2001) KLP felülrŒlclaimed that some combinations of their newly identified compounds were more powerful in attracting females than the conventional floral baits (based on 4-methoxy cinnamaldehyde.

KLPfero+

KLPflor+ Recently we developed the KLP (“hat”)KLPflor+ trap (introduced at the Bratislava Diabrotica conference in 2005), which is a KLP felülrŒlnon-sticky trap design and can be baited with pheromonal or floral bait.

KLPfero+

KLPflor+ As presented on the Bratislava % 70 P<0.0001 conference,KLPflor+ we found vs. that PALs: the KLP trap 60 50 whenfemale baited with% inthe catchfloral bait was 40 especially suitable for the capture of SE) 30 (+ 20 34058 32832 female WCR. 10 beetles beetles mean female % 0 Debrecen, 2004 KLPflor+ PALs KLPflor+ PALs 400 The KLPflor+ caught SE) 350 females in significantly 300 higher ratio than the PALs! 250 200 150

mean female ratioo (+ mean female ratioo 100 normalized against ratio in PALs normalized against 50 0 11521630 13 1 8 July August September October % 70 P<0.0001 KLPflor+ vs. PALs: 60 50 female % in catch 40 SE) 30 (+ 20 34058 32832 10 beetles beetles mean female % 0 Debrecen, 2004 KLPflor+ PALs KLPflor+ PALs 400 The KLPflor+ caught SE) 350 females in significantly 300 higher ratio than the PALs! 250 200 150 mean female ratioo (+ mean female ratioo 100 normalized against ratio in PALs normalized against 50 0 11521630 13 1 8 July August September October Encouraged by this we set out to compare efficiency of female- targeted Diabrotica baits. The following treatments were tested:

”FLORAL” = 4-methoxy cinnamaldehyde + indole (floral bait in use for WCR – served as positive control); ”HAMMACK” = ß-ionone + methyl salicylate + ß-caryophyllene [According to Hammack et al. (2001) this combination attracted more females than the known floral WCR bait]; ”BARB” = 4-methoxyphenethyl alcohol + cinnamaldehyde + (E)- anethole + indole (attractant used for D. barberi in North America); ”MAIZE” = phenylacetaldehyde + 2-phenylethanol + methyl anthranylate + eugenol + benzaldehyde (compounds shown out from maize silk or tassels in previous studies) ”RELAT” = 1-phenylethanol + 3-methyl eugenol + benzyl alcohol + benzyl acetate + geraniol (floral compounds showing attraction to other beetles in previous studies); ”UNB” = unbaited traps – served as negative control In trapping tests femaleFemale % in %catches in catch was equally high in treatments BARB, FLORAL, MAIZE and RELAT.

Hajdúböszörmény, 2005 Debrecen, 2005 July 5 - Pusztazámor, 2005 July 7 - September 19. Total September 19. Total August 1 - 19. Total caught: 10595 beetles caught: 67018 beetles caught : 19433 beetles mean+SE c mean+SE c mean+SE 90 b 70 b 60 b a a a %%%80 60 50 70 50 60 40

50 40 30 40 30

30 20 20 20 10 10 10

0 0 0 UNB UNB UNB

BARB BARB BARB MAIZE MAIZE MAIZE

RELAT RELAT RELAT FLORAL FLORAL FLORAL

HAMMACK

HAMMACK HAMMACK It was surprising that HAMMACK (which had been Female % in catch described as a strong female attractant by US scientists) was not more attractive for females than unbaited controls.

50 40 30 40 30

30 20 20 20 10 10 10

0 0 0 UNB UNB UNB

BARB BARB BARB MAIZE MAIZE MAIZE

RELAT RELAT RELAT FLORAL FLORAL FLORAL

HAMMACK

HAMMACK HAMMACK Among treatments moreFemale attractive % in for catch females, none produced significantly higher female percentages than FLORAL.

50 40 30 40 30

30 20 20 20 10 10 10

0 0 0 UNB UNB UNB

BARB BARB BARB MAIZE MAIZE MAIZE

RELAT RELAT RELAT FLORAL FLORAL FLORAL

HAMMACK

HAMMACK HAMMACK Seasonal pattern of female %-s for the two ”best” baits suggested a slight (but not convincing) tendency of higher female ratios in MAIZE mean+SE 120

% 100 Hajdúböszörmény, 80 2005 July 7 - SeptemberA)Diabrfloral 19. Total 60 catch:D)pheneugbenz 9245 beetles 40

Cell Mean for FEM%(10felett) 0 Jul 5 Sep 3 Sep 8 Aug 3 Aug 7 Jul 11 Jul 15 Jul 20 Jul 26 Jul 30 Sep 14 Sep 19 Aug 11 Aug 15 Aug 20 Aug 25 Aug 30

mean+SE 100 90 % 80 Debrecen, 2005 July 5 - 70 September 19. Total 60 catch:A)Diabrfloral 53281 beetles 50 40 D)pheneugbenz 30 20 10

Cell Mean for FEM%(10felett) 0 Jul 7 Sep 2 Sep 9 Sep 6 Aug 3 Aug 7 Jul 11 Jul 14 Jul 19 Jul 22 Jul 27 Jul 31 Sep 13 Sep 16 Sep 19 Aug 10 Aug 13 Aug 17 Aug 19 Aug 24 Aug 28 Aug 31 FLORAL MAIZE However, as far as meanMean numbers catches captured of females were concerned, FLORAL caught far more beetles than any of the other treatments.

Hajdúböszörmény, 2005 Debrecen, 2005 July 5 - Pusztazámor, 2005 July 7 - September 19. Total September 19. Total August 1 - 19. Total catch: 6938 beetles catch: 32267 beetles catch: 2655 beetles e d d mean+SE c mean+SE c mean+SE c 90 b 300 b 100 b a a a 80 90 250 80 70 70 60 200 60 50 150 50 40 40 30 100 30

20 20 50 10 10

0 0 0 UNB UNB UNB BARB BARB BARB MAIZE MAIZE MAIZE RELAT RELAT RELAT

FLORAL FLORAL FLORAL

HAMMACK HAMMACK HAMMACK If female antennae would response better to a given compound, this chemical would show perspective to be tested for a female-targeted bait

Consequently, air flow with antennal responses of stimulus WCR were recorded by an EAG apparatus insect antenna

glass capillary electrodes 4 Sample EAG response elicited by methyl- anthranilate No difference was found in EAG response spectra between males % and females – no indication of female-specific compounds 250 225 200 175 means of 9

SE) 150 125 antennae 100 control 75 50 25 0

300

250

200 means of 10

150 antennae mean normalized responses (+mean normalized responses 100

0 air levegö linalool air eugenol

geraniol linalool eugenolgeraniol isosafrol

isosafrol lavandulol

beta-ionone lavandulol cinnamyl OH linalool eugenol

benzaldehyde beta-ionone geraniol benzylalcohol trans-anethol isosafrol anisyl acetone

benzyl acetate trans-anethol i-Amyl alcohol anisylbenzaldehyde acetonebenzyl acetate methyl eugenol lavandulol

benzyl alcohol isoamyl acetate 2-phenylethanol isoamylisobutyl acetate acetateisobutyl acetate methyl eugenol methylsalicylate

cinnamyl acetate isoamyl alcohol 2-phenylethanol beta-ionone cinnamylcinnamyl acetate alcohol methyl salicylatephenethyl alcoholphenethyl acetate trans-anethol

cinnamyl OH phenethyl acetate benzaldehyde phenylacetaldehyde methyl anthranilate benzylalcohol benzyl acetate anisyl acetone methyl anthranilate i-Amyl alcohol isoamyl acetate methyl eugenol 2-methyl-1-propanol isobutyl acetate

2-methyl-1-propanol phenylacetaldehyde 2-phenylethanol methylsalicylate cinnamyl acetate

trans-cinnamaldehydephenethyl acetate methyl anthranilate

phenylacetaldehyde

4-metoxyphenethyl2-methyl-1-propanol alcohol 4-metoxyphenethyl-alcohol

4-methoxy cinnamaldehyde trans-cinnamaldehyde trans-cinnamaldehyde (2006)

para-methoxy cinnamic aldehyde phenethyl alcohol (kontroll) átlag

phenethyl alcohol (control)

4-metoxyphenethyl-alcohol methoxy cinnamic aldehyde In conclusion, so far the most efficient female-targeted trap- bait combination for WCR is the conventional floral attractant applied in KLPflor+ traps.

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