Disruption of Western Pine Beetle, Dendroctonus brevicomis, Response to Baited Traps With Nonhost Angiosperm Volatiles and Verbenone

Transcription

1 Disruption of Western Pine Beetle, Dendroctonus brevicomis, Response to Baited Traps With Nonhost Angiosperm Volatiles and Verbenone CHRISTOPHER J. FETTIG 1 and DEZENE P. W. HUBER 1,2 1 PACIFIC SOUTHWEST RESEARCH STATION USDA FS 2 UNIVERSITY OF CALIFORNIA - DAVIS CALIFORNIA FOREST PEST COUNCIL MEETING WOODLAND, CA 2004

2 Western Pine Beetle FS harvests (2003): 1.5 BBF

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5 Semiochemicals?

6 Verbenone Primary antiaggregation pheromone of the MPB, SPB, WPB First identified in males of the SPB and WPB (Renwick 1967), and subsequently in the hindgut of emergent and feeding female MPB (Pitman and others 1969). Sources: (1) beetles themselves, (2) auto- oxidation of α-pinene and subsequently cis- and trans-verbenol to verbenone, and (3) auto- oxidation from cis- and trans-verbenol to verbenone by microorganisms

7 Function It is assumed that verbenone reduces the negative impacts of intraspecific competition by reducing the overcrowding of developing brood. VACANCY

8 Release Device Verbenone Pouch 95.9% A.I. verbenone manufactured by Phero Tech Inc., Delta, BC Registration No.: CN-1 (1999) Release Rate 50 mg/d at 30º C Bubblecaps (8 mg/d at 30º C) Bedard and others (1980), Tilden and Bedard 1988

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10 Mean Number of Trees Attacked by WPB ± SEM (2002) Control Group 6.8 ± 2.6 Verbenone Group 9.0 ± 3.3 No significant difference between treatment means (P = 0.84)

11 Mean Number of Trees Attacked by WPB ± SEM (2003) Control Group 7.8 ± 2.7 Verbenone Group 4.8 ± 1.2 No significant difference between treatment means (P = 0.33)

12 Challenges Passive release (Shea, Strom, Gillette, others) Movement (and concentrations) affected by abiotic and stand conditions (Shea, Thistle, Fettig, others) Positive trends appear common in many studies (MPB/LP), inherent variation is problematic Photoisomerization

13 UV O O Verbenone (active antiaggregant) Chrysanthenone (inactive) (Kostyk et al. 1993)

14 Searching Host? YES NO YES Already infested? YES NO NO Is uninfested host suitable/susceptible? YES Is intraspecific competition going to be heavy? NO VACANCY YES With conspecifics? NO Is interspecific competition going to be heavy? NO YES Initiate attack (Derived from Borden, 1997)

15 Sudden explosion of data ~35 research publications since 1989 The Art of Chemical Camouflage Borden et al. 1997; Borden et al. 1998, 2003; Byers et al. 1998; de Groot & McDonald1999; Deglow & Borden 1998a,b; Dickens et al. 1992; Guerrero et al. 1997;Huber 2001; Huber et al. 1999, 2000a,b; Huber & Borden 2001a,b,c; Jactel et al. 2001; Kohnle et al.1992; Poland et al. 1998; Poland & Haack 2000; Schlyter et al. 1995, 2000; Schroeder 1992; Tømmerås 1989; Tømmerås & Mustaparta 1989; Wilson et al. 1996; Zhang 2001; Zhang et al. 1999a,b, 2000, 2001, 2002; Zhang and Schlyter 2003; Zhang 2003

16 Dendroctonus brevicomis - limited Behaviorally active NHVs * (Z)-2-hexenol Hexanal (E)-2-hexenal (M/F) (E)-2-hexenol (M/F) 1-hexanol (Z)-3-hexenol (Poland et al. 1998) *Active alone Active in blend only Not active

17 Advantages: 1. Seem to be efficacious in a number of spp. 2. Augments efficacy of verbenone. 3. Price.

18 ~Prices (Sigma-Aldrich): Verbenone - $0.30/g MCH - $0.48/g GLVs 1-hexanol - <$0.01/g hexanal - $0.06/g (E)-2-hexenal - $0.12/g (E)-2-hexenol - $0.17/g (Z)-3-hexenol - $0.18/g Other NHVs conophthorin - expensive? benzaldehyde - $0.01/g benzyl alcohol - $0.03/g salicylaldehyde - $0.03/g guaiacol - $0.05/g nonanal - $0.05/g 1-octen-3-olol - $0.21/g 3-octanol - $0.14/g

19 Disadvantages: 1. Multi-component blend usually required for efficacy. 2. The one compound that is often efficacious on its own (conophthorin) has no readily-available available commercial source. 3. Effects on other organisms are relatively unknown. 4. Unregistered.

20 Experiments 1& Shasta-Trinity National Forest ( N, W, 3892 elevation) Stand description (based on ac subplots): Average BA: 137 sq ft/ac Average BA ponderosa pine: 131 sq ft/ac Average TPA: 88 Average crown cover: 27% Slope: 1% Aspect: N/A

21 Green Leaf Volatiles (GLV) (E)-2-hexenal: green leaf volatile; significantly reduced aggregation of D. brevicomis (Poland et al. 1998); reduced aggregation of some ambrosia beetles (Borden et al. 1997), but not others (Deglow and Borden 1998) (E)-2-hexen-1-ol: green leaf volatile; significantly reduced aggregation of D. brevicomis (Poland et al. 1998) (Z)-2-hexen-1-ol: green leaf volatile; significantly reduced aggregation of D. brevicomis (Poland et al. 1998)

22 Bark Volatiles (BV) benzyl alcohol: bark volatile of several angiosperm trees, particularly aspen (Huber et al. 2000); disrupted aggregation of D. ponderosae (Borden et al. 1998) benzaldehyde: bark volatiles of several angiosperm trees; reduced aggregation of D. ponderosae (Borden et al. 1998) conophthorin: bark volatile of several angiosperm trees, particularly birches (Byers et al. 1998, Huber et al. 1999); reduced aggregation of D. ponderosae and D. pseudotsugae (Huber et al. 1999); anitaggregation pheromone of several scolytid species guaiacol: bark volatile of several angiosperm trees (Huber et al. 2000); reduced aggregation of D. ponderosae in presence of other NAVs (Huber and Borden 2001a) nonanal: bark volatiles of several angiosperm trees (Huber et al. 2000); reduced aggregation of D. ponderosae in several studies (Borden et al. 1998, Huber and Borden 2001a,b) salicylaldehyde: bark volatile of several angiosperm trees (Huber et al. 2000); reduced aggregation of D. ponderosae in presence of other NAVs (Huber and Borden 2001b)

23 untreated control WPB tree bait (frontalin, exo- brevicomin, myrcene) verbenone (4 mg/24h) GLV + WPB bait GLV + verbenone + WPB bait BV + WPB bait BV + verbenone + WPB bait GLV + BV (NAV( NAV) ) + WPB bait NAV + verbenone + WPB bait Treatments Exp. 1

24 Volatile Source Release Device Release (mg/24h) benzyl alcohol Fisher Scientific Phero Tech bubblecap 1.3 (20 C) benzaldehyde Fisher Scientific Phero Tech flexlure 3.5 (20 C) conophthorin Phero Tech 0.4 ml polyethylene vial 3.0 (28 C) guaiacol Sigma Aldrich Phero Tech bubblecap 5.0 (20 C) nonanal Sigma Aldrich Phero Tech bubblecap 3.5 (20 C) (E)-2-hexenal Bedoukian Research Phero Tech bubblecap 3.5 (20 C) (E)-2-hexen-1-ol Bedoukian Research Phero Tech bubblecap 3.8 (20 C) (Z)-2-hexen-1-ol Bedoukian Research Phero Tech bubblecap 3.8 (20 C) salicylaldehyde Sigma Aldrich Phero Tech bubblecap 5.0 (20 C) verbenone Phero Tech Phero Tech bubblecap 4.0 (30 C) frontalin exo-brevicomin myrcene Phero Tech WPB tree bait 250µL L Eppendorf vial 250µL L Eppendorf vial 1.8 ml X 2 Eppendorf vials 3.0 (24 C) 3.0 (24 C) 18.0 (24 C)

25 Results Exp. 1 No significant treatment X gender interaction (F 7, 464 = 0.52, P > 0.82) Significant treatment effect observed (F = 9.53, P < 0.001) 7, 232 Significantly more females than males were collected (paired T-test, P < 0.01). Ratio of males to females was 0.52.

26 WPB bait alone a a WPB + GLV WPB + BV ab ab ab ab WPB + NAV ab ab WPB + Lo Verb b b WPB + Lo Verb + BV bc bc WPB + Lo Verb + GLV WPB + Lo Verb + NAV bc c c bc 85% reduction 71% reduction Unbaited MALES FEMALES Unpublished data. 23,783 individuals collected Mean trap catch + SEM

27 Based on these results we asked three additional questions: Is the NAV effect (signal) overwhelmed by higher release rates of verbenone? Can components be removed from the NAV blend without sacrificing efficacy? Do responses differ between alcohols and aldehydes (previous blends examine by source bark vs. green leaf)?

28 Treatments Exp. 2 Untreated control WPB tree bait WPB + Verb (4mg/24h) WPB + Verb (50 mg/24h) WPB + NAV+C + Verb4* WPB + NAV+C + Verb50 WPB + NAV-C C + Verb4* WPB + NAV-C C + Verb50 WPB + ALD + Verb4* WPB + ALD + Verb50 WPB + ALC + Verb4* WPB + ALC + Verb50 * Definitions on next slide

29 Definitions NAV+C = includes conophthorin NAV-C C = without conophthorin NAV aldehydes: benzaldehyde, nonanal, salicylaldehyde, (E)-2-hexenal NAV alcohols: benzyl alcohol, guaiacol, (E)-2-hexen hexen-1-ol, and (Z)-2-hexen hexen-1-ol

30 Results Exp. 2 No significant treatment X gender interaction (F 10, 638 = 0.36, P > 0.96) Significant treatment effect observed (F = 18.78, P < 0.001) 10, 319 Significantly more females than males were collected (paired T-test, P < 0.001). Ratio of males to females was 0.43.

31 WPB bait alone a WPB + Lo Verb b b WPB + Hi Verb b b WPB + ALD + Hi Verb b b WPB + ALD + Lo Verb b b WPB + ALC + Lo Verb bc bc WPB + ALC + Hi Verb bc bc WPB + NAV C + Lo Verb bc bc WPB + NAV + C + Lo Verb bc bc WPB + NAV + C + Hi Verb WPB + NAV C + Hi Verb c c c c 87% reduction 75% reduction Unbaited MALES FEMALES Mean trap catch + SEM Unpublished data. 20,795 individuals collected..

32 Conclusions overall This population of WPB was not as behaviorally- responsive to NAVs as several other congenerics (Zhang and Schlyter 2004). It cannot be said with certainty that all of the NAVs included here are detected by WPB antennae as no EAG data concerning NAVs exist for this species. Our blend of NAVs was effective in increasing the efficacy of verbenone in baited traps. NAVs augmented the disruptive effect of 4 and 50mg/day verbenone to levels significantly below that of verbenone alone.

33 Conclusions overall Conophthorin, an NAV that is known to disrupt the response of other bark beetles to attractant-baited traps is not required for efficacy. The minimal disruptive blend of the NAVs likely includes both alcohol and aldehyde fractions. The addition of NAVs to verbenone may be critical for developing semiochemical-based management techniques that minimize ponderosa pine losses from WPB infestations.

34 Further testing (2005): Further testing (2005): = >5000 (oral), >5000 (dermal) = 520 (oral), 4600 (dermal) = 307 (oral), 2000 (dermal) 1) 1) Trapping bioassay: release rates, toxicity Trapping bioassay: release rates, toxicity - nonanal: nonanal: LD LD 50 - guaiacol: guaiacol: LD LD 50 - carbaryl: carbaryl: LD LD = >5000 (oral), >5000 (dermal) 50 = 520 (oral), 4600 (dermal) 50 = 307 (oral), 2000 (dermal) 2) 2) EAG EAG analyses analyses 3) 3) Efficacy Efficacy for for protection protection of of single single trees trees or or small small groups groups

35 Acknowledgments Lab: McKelvey, Dabney, Patterson, Borys R5: McCloud RD Extramural funding: Western Bark Beetle Initiative Grant (#7); FHP sponsor S. Smith