Mountain Pine Beetle-Host Tree Interactions in Alberta Nadir Erbilgin and Maya Evenden
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 E-mail: erbilgin@ualberta.ca
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
Mountain Pine Beetle (MPB) treecanada.ca 4 4
Emergence Dispersal & Host Selection Pupae Overwinter Aggregation & Colonization 5
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
Host & Range Expansion of MPB MPB
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
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 http://www.encyclopedia.com/rankimages.aspx?topicid=2830 9 9
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 http://www.squidoo.com/terpene-chemistry 10 10
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
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: 1013-1026 12 12
% (+ SD) % (+ SD) α- Pinene 3-Carene Jack Pine β-phellandrene Lodgepole Pine 13 13
Field Experiment in Jack Pine and Lodgepole Pine Forests in 2010-2011 14 14
Water Treatment 15
Biological Treatment 16
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
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
Monoterpene content (ng/mg) ± S.E. α-pinene Chirality 350 Lodgepole pine 350 Jack pine 300 300 250 250 200 200 150 150 100 100 50 50 0 (-)-α-pinene (+)-α-pinene 0 (-)-α-pinene (+)-α-pinene 19 19
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
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
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
MPB Pheromones on LP & JP Tree Species Mean Amounts (ng/µl) of Pheromones Released per pair beetle Transverbenol Exobrevicomin Frontalin Verbenone LP 0.5 ± 0.2 0.01 ± 0.0 0.01 ± 0.0 0.5 ± 0.3 JP 1.1 ± 0.8 0.01 ± 0.0 0.001 ± 0.0 0.3 ± 0.2 Several folds of 3-carene released from jack pine 23 23
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
MPB Attraction Treatments Total Numbers Total Female Male JP Pher +3-Carene 471 207 264 LP Pher + 3-Carene 385 147 238 JP Pheromone 295 101 194 LP Pheromone 261 75 186 Blank 2 1 1 25 25
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
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
MPB success in BC Dezene Huber http://www.for.gov.bc.ca/hfp/mountain_pine_beetle/maps.htm
Pine distribution in Canada 29
http://mpb.alberta.ca/res ources/maps.aspx MPB eastward spread
Climate Moisture Index Climate Moisture Index (Hogg, 1997) output using BioSim (Barry Cooke) 31
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
Field Experiment Hybrid Zone-2009 33
Environmental Treatments 3.65 m 4.27 m water-deficit 34 watered
Environmental Treatments 35
Biological Treatments 36
Beetle Rearing Experiment Bolts were inoculated with 4 pairs of MPB per bolt 37
Beetle Condition Fresh weight Size Fat content Maternal gallery length 38
Beetles from water stressed trees are fatter Two factor ANOVA: water regime F(1,23)=6.866, p<0.05 39
Field Experiment Pure Species-2010 Environmental Treatments Biological Treatments Water deficit Ambient 40
Beetle Condition Experiment Bolts for condition experiment Phloem added to diet 41
Better beetle survival on diet with lodgepole pine phloem 42
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
Choice Experiment: Better establishment in water-stressed trees p=0.044 1 2 3 4 5 replicate 44
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
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
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 0.88 5.53 ± 0.94 (35) 2.86 ± 0.71 (35) 1.75 ± 0.07 (35) 13.81 ± 0.54 (35) 0.09 ± 0.01 (34) Middle 0.85 5.11 ± 0.97 (33) 2.35 ± 0.52 (33) 1.74 ± 0.08 (33) 14.85 ± 0.48 (33) 0.09 ± 0.01 (33) Old 0.83 3.14 ± 0.74 (15) 1.23 ± 0.46 (15) 1.55 ± 0.14 (15) 13.44 ± 0.56 (15) 0.07 ± 0.02 (13) Male Young 0.90 5.95 ± 1.05 (29) 3.55 ± 0.87 (29) 1.93 ± 0.12 (29) 10.74 ± 0.47 (29) 0.05 ± 0.01 (30) Middle 0.88 4.18 ± 0.61 (37) 1.68 ± 0.41 (37) 1.91 ± 0.18 (37) 10.66 ± 0.36 (37) 0.05 ± 0.01 (30) Old 0.89 2.12 ± 0.61 (25) 1.25 ± 0.54 (25) 1.85 ± 0.29 (25) 10.59 ± 0.37 (25) 0.09 ± 0.01 (16) Longest flying beetle= 26 km! 47
Pre-flight weight dictates flight capacity Total distance flown Longest single flight Total flight duration P<0.00004 P<0.00018 P<0.00004 Flight propensity: P<0.000002 48
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
Beetle age influences flight Total distance flown Longest single flight Total flight duration P<0.00081 P<0.00767 P<0.01305 50
Flight velocity Interaction between pre-flight weight and emergence period affects flight velocity P=0.00036 Small beetles fly faster Late emerging beetles fly faster 51
Energy use during flight: weight loss Age influences energy use in flight P= 0.00002 Pre-flight weight influences energy use P= 0.00332 Older beetles lose a smaller proportion of body weight during flight Big beetles lose a smaller proportion of body weight 52
Energy use during flight: fat loss Beetles use fat to fuel flight P= 0.0000 53
Energy use during flight: fat loss All beetles Flown beetles Females are fatter than males P= 0.00012 Females use more fuel during flight 54
Energy use during flight: fat loss Distance flown predicts beetle lipid content P= 0.00096 55
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
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