Mountain Pine Beetle-Host Tree Interactions in Alberta. Nadir Erbilgin and Maya Evenden

Transcription

1 Mountain Pine Beetle-Host Tree Interactions in Alberta Nadir Erbilgin and Maya Evenden

2 Mountain Pine Beetle-Host Tree Interactions in Alberta (Part I) The Tree Is Jack Pine A Suitable Host Tree? Nadir Erbilgin 1 Inka Lusebrink 1,2, Cary Ma 1, Caitlyn Andres 1, Bin Shan 1, Molly Penzes 1, Maya Evenden 2 1 Department of Renewable Resources, U of A, Edmonton, Canada 2 Department of Biological Sciences, U of A, Edmonton, Canada Nadir Erbilgin: Canada Research Chair & Assistant Professor Department of Renewable Resources erbilgin@ualberta.ca

3 Outline Mountain pine beetle Population level & host plant interactions Proposed invasion dynamics Tree resistance to bark beetles Include chemical defenses: Constitutive & induced defenses Field experiments Experiments with mature jack pine and lodgepole pine Quantification of mountain pine beetle pheromone on jack pine vs. lodgepole pine Field experiments testing attraction of pheromones Conclusions 3 3

4 Mountain Pine Beetle (MPB) treecanada.ca 4 4

5 Emergence Dispersal & Host Selection Pupae Overwinter Aggregation & Colonization 5

6 Population Levels & Host Tree Interactions Endemic level Associated with trees with reduced defenses Facilitative interactions with other biotic agents Population dynamic is influenced by tree resistance, winter mortality, and predation Epidemic level Associated with healthy trees Rely on sudden mass colonization ability Distinguished by high brood productivity Characterized by long distance dispersal Predation and tree resistance have little impact on population dynamics 6 6

7 Host & Range Expansion of MPB MPB

8 Plant resistance, particularly chemical defenses, is an important tool to understand plant responses to organisms as well as indirect interactions between different organisms or between an organism and environment 8 8

9 Conifer Defenses Against Bark Beetles Two basic types: Mechanical: Structural elements that provide toughness or thickness to the tissues and inhibit chewing or pulling apart of the bark Phloem Cambium Cork bark Sapwood Heartwood 9 9

10 Conifer Defenses Against Bark Beetles Chemical Healthy trees may put up defenses by producing resin, which contain a number of insecticidal and fungicidal compounds that can affect a number subcortical organisms Offen resin occur as pools of stored chemicals, also called secondary compounds, (e.g., terpenes, phenolics) that can be released upon attack

11 Constitutive & Induced Defenses Constitutive defenses Present before an attack Anatomical Chemical Inducible defenses Activated in response to an attack Anatomical Chemical General and broad-based defense that may repel or delay invasion Level of resistance is determined by genetics and genetics*environment interaction May be targeted at specific attackers Fine-tuned according to severity of threath Only turned on when they are needed 11 11

12 Experiments Goal: Compare and contrast chemical defenses of lodgepole pine and jack pine to mountain pine beetle in manipulative field and greenhouse experiments Pure species of jack and lodgepole pines & their hybrid Volatile chemicals released from host trees Phloem chemistry: Monoterpenes Greenhouse experiment: One-year old seedlings Field experiment: Hybrid and pure pine species Lusebrink et al. 2011: J Chem Ecol. 37:

13 % (+ SD) % (+ SD) α- Pinene 3-Carene Jack Pine β-phellandrene Lodgepole Pine 13 13

14 Field Experiment in Jack Pine and Lodgepole Pine Forests in

15 Water Treatment 15

16 Biological Treatment 16

17 Monoterpene Emission For both lodgepole pine (LP) and jack pine (JP) Fungal inoculations increased monoterpene emission Water did not influence monoterpene emission JP emitted less monoterpene than LP 17

18 Phloem Monoterpenes 18 For both LP and JP Fungal inoculations increased monoterpene concentration Water did not influence monoterpene concentration Concentration of monoterpenes in JP was lower than in LP 18

19 Monoterpene content (ng/mg) ± S.E. α-pinene Chirality 350 Lodgepole pine 350 Jack pine (-)-α-pinene (+)-α-pinene 0 (-)-α-pinene (+)-α-pinene 19 19

20 Role of Host Tree Species in Bark Beetle Aggregation Pheromonal communication among conifer infesting bark beetles is closely linked to host tree chemistry Presence of host plant material may influence the production and release of pheromones Some bark beetles may convert host plant monoterpenes to pheromones Exposure to host monoterpenes may also stimulate de novo synthesis of pheromones 20 20

21 Role of Host Tree Species in MPB Aggregation A mass attack involves a complex synergism of host-produced (kairomones) and beetle-produced (pheromones) volatile chemicals Trans-verbenol (female only): Oxidation of -pinene and preferentially attractive to males -Pinene, myrcene, 3-carene synergize pheromone Exo-brevicomin (male only): At low concentrations attracts mainly females and at high concentration regulate attack density along with frontalin (male only) and anti-aggregation pheromone verbenone (both sexes) Verbenone: Autoxidation of the kairomone -pinene or microbial conversion of trans-verbenol 21 21

22 Pheromone Collection 5 trees per species and one bolt per trees Each bolt received 4-pair of beetle inoculations Two entrance holes per bolt used for collection Sampling: 12hr, 24hr, 36hr, 48hr, 72hr, 96hr, 120hr 22 22

23 MPB Pheromones on LP & JP Tree Species Mean Amounts (ng/µl) of Pheromones Released per pair beetle Transverbenol Exobrevicomin Frontalin Verbenone LP 0.5 ± ± ± ± 0.3 JP 1.1 ± ± ± ± 0.2 Several folds of 3-carene released from jack pine 23 23

24 Treatments Treatments were tested in a LP forest with active MPB populations in west of Alberta (Grande Prairie) 1. Pheromones (trans-verbenol, exo-brevicomin) emitted from beetle on JP 2. Pheromone emitted from beetle on LP 3. Pheromone emitted from beetle on JP plus 3-carene 4. Pheromone emitted from beetle on LP + 3-carene 5. Blank control 8 blocks, each with 5 traps, each with a single treatment 8 collection periods (every 4-day), but only four collections were included in analysis 24 24

25 MPB Attraction Treatments Total Numbers Total Female Male JP Pher +3-Carene LP Pher + 3-Carene JP Pheromone LP Pheromone Blank

26 Conclusion: Jack Pine X MPB Interactions JP is as susceptible to MPB and its associated fungi MPB reproduction & survival are similar between JP and LP JP emitted more 3-carene and myrcene in response to fungal inoculations than LP MPB and native organisms in JP forests can influence MPB invasion MPB can elicit attraction on JP and stressed JP trees are especially vulnerable to MPB attacks as they provide important host location cues for MPB attraction Amount of trans-verbenol emitted by female MPB on JP was higher than on LP Pheromones emitted from JP plus 3-carene attracted significantly more MPB than any other treatments 26 26

27 Mountain pine beetle-host tree interactions in Alberta: Part II The Beetle Maya L. Evenden 1, Inka Lusebrink 1,2, Jared Sykes 1, Caroline Whitehouse 1, and Nadir Erbilgin 2 1 Department of Biological Sciences, University of Alberta 2 Department of Renewable Resources, University of Alberta

28 MPB success in BC Dezene Huber

29 Pine distribution in Canada 29

30 ources/maps.aspx MPB eastward spread

31 Climate Moisture Index Climate Moisture Index (Hogg, 1997) output using BioSim (Barry Cooke) 31

32 Objectives 1. To develop a chemical profile of volatile organic compounds (VOCs) and phloem and needle monoterpene content from mature pine host trees (Hybrids, Lodgepole pine, Jack pine). 2. To evaluate if VOC profiles vary with different environmental (water vs. water deficit; ambient vs. water deficit). 3. To evaluate if VOC profiles vary with biological treatments (fungal inoculation with Grosmania clavigera). 4. To link tree manipulations to subsequent to beetle fitness. 32

33 Field Experiment Hybrid Zone

34 Environmental Treatments 3.65 m 4.27 m water-deficit 34 watered

35 Environmental Treatments 35

36 Biological Treatments 36

37 Beetle Rearing Experiment Bolts were inoculated with 4 pairs of MPB per bolt 37

38 Beetle Condition Fresh weight Size Fat content Maternal gallery length 38

39 Beetles from water stressed trees are fatter Two factor ANOVA: water regime F(1,23)=6.866, p<

40 Field Experiment Pure Species-2010 Environmental Treatments Biological Treatments Water deficit Ambient 40

41 Beetle Condition Experiment Bolts for condition experiment Phloem added to diet 41

42 Better beetle survival on diet with lodgepole pine phloem 42

43 Choice Experiment: lodgepole pine Treatments: (N=5) 1. Control 2. Water deficit/ fungus 3. Water deficit/ no fungus 4. Ambient/ fungus 5. Ambient/ no fungus 43

44 Choice Experiment: Better establishment in water-stressed trees p= replicate 44

45 Summary 1. Beetles that emerged from water deficit bolts had a higher fat content. 2. There was higher survival of beetles reared on lodgepole pine diet. 3. Beetles become better established in water stressed trees. 45

46 Beetle Dispersal 1. Beetles reared from naturally infested lodgepole pine. 2. Three age groups tested: Young, 1-3 days; Middle, 5-7 days; Old, 9-11 days. 3. Males and females flown for 24 h on different days. 4. Total flight distance, duration; longest single flight; flight velocity. 5. Weight loss and proportion fat loss during flight as measures of energy use. 46

47 Beetle Dispersal Table 1. The effect of sex and age on flight performance of Dendroctonus ponderosae. Values are mean ± SE and sample size is stated in brackets. Proportion that flew Total distance flown (km) Longest single flight (km) Fight velocity (km/hr) Pre-flight weight (mg) Proportion of fat remaining after flight Female Young ± 0.94 (35) 2.86 ± 0.71 (35) 1.75 ± 0.07 (35) ± 0.54 (35) 0.09 ± 0.01 (34) Middle ± 0.97 (33) 2.35 ± 0.52 (33) 1.74 ± 0.08 (33) ± 0.48 (33) 0.09 ± 0.01 (33) Old ± 0.74 (15) 1.23 ± 0.46 (15) 1.55 ± 0.14 (15) ± 0.56 (15) 0.07 ± 0.02 (13) Male Young ± 1.05 (29) 3.55 ± 0.87 (29) 1.93 ± 0.12 (29) ± 0.47 (29) 0.05 ± 0.01 (30) Middle ± 0.61 (37) 1.68 ± 0.41 (37) 1.91 ± 0.18 (37) ± 0.36 (37) 0.05 ± 0.01 (30) Old ± 0.61 (25) 1.25 ± 0.54 (25) 1.85 ± 0.29 (25) ± 0.37 (25) 0.09 ± 0.01 (16) Longest flying beetle= 26 km! 47

48 Pre-flight weight dictates flight capacity Total distance flown Longest single flight Total flight duration P< P< P< Flight propensity: P<

49 Preflight weight is affected by sex and emergence time Interaction between pre-flight weight and emergence period affects distance and duration of flight 49 Females weigh more than males BUT no effect of sex on flight

50 Beetle age influences flight Total distance flown Longest single flight Total flight duration P< P< P<

51 Flight velocity Interaction between pre-flight weight and emergence period affects flight velocity P= Small beetles fly faster Late emerging beetles fly faster 51

52 Energy use during flight: weight loss Age influences energy use in flight P= Pre-flight weight influences energy use P= Older beetles lose a smaller proportion of body weight during flight Big beetles lose a smaller proportion of body weight 52

53 Energy use during flight: fat loss Beetles use fat to fuel flight P=

54 Energy use during flight: fat loss All beetles Flown beetles Females are fatter than males P= Females use more fuel during flight 54

55 Energy use during flight: fat loss Distance flown predicts beetle lipid content P=

56 Summary Beetles prefer water deficit trees and are fatter when reared in water deficit trees Beetle pre-flight weight dictates flight capacity of MPB Positive relationship between pre-flight weight and propensity to fly, flight distance, longest single flight, and total time spent flying Flight capacity is similar among male and female beetles Flight distance and duration decreased with beetle age Smaller, late emerging beetles fly faster Beetle use fat to fuel flight and distance flown predicts body lipid composition Females use more fat during flight 56

57 Future Plans Analysis of extracted fat Trade-offs between flight and reproduction Influence of host volatiles on flight Comparison of flight capacity of beetles reared in jack pine vs. lodgepole pine Influence of flight on pheromone signalling 57