1. The Mountain Pine Beetle: Ideas on Population Dynamics & Management in lodgepole pine

2. (1)I’ll review some of the basics of Dendroctonus ponderosae (MPB) as I go along. (2)I’ll concentrate on MPB host selection behavior and barkbeetle management. (3) I hope my thoughts will not crash: They’re new.

3. When you’re looking under the bark of a dead pine, the MPB galleries are sometimes difficult to describe.

4. Important Review Topics: 1.MPBs have a sophisticated host selection scheme; 2. Populations disperse out of their host trees in spring and go into a down- wind-random-dispersal flight; 3. Pioneering females find a weakened pine and expel a population-attracting pheromone – cis-verbenol. 4. When the MPB attack density of a selected pine reaches a point where the sexes are 50:50 the tree is no longer attractive. Why? At mating males expel a masking pheromone – verbenone. 5. The switching mechanism takes over if the MPB population is high.

5. There are scattered susceptible lodgepole pines across the landscape – focus trees. So let’s look at an endemic MPB population

6. The members of a low MPB population have the tough task of being able to find & colonize these scattered, water-stressed focus trees. What they have is a super host- selection scheme.

7. Flying MPB Adults MPB population is in a down-wind random dispersal flight. Susceptible pine (focus tree) Pioneer cis-verbenol MPB population now flies up-wind in a concentrated flight. Dispersal loss drops significantly. Mass Attack 1 st 2 nd

8. Flying MPB Population Susceptible pine (focus tree) Pioneer cis-verbenol 1 st 2 nd Random dispersal Dispersal mortality is huge Directed concentration Low mortality

9. Dispersal flight: Search the landscape for susceptible hosts – focus trees. Mixes the gene pool and this is important: a period when the fittest are selected. Provides a huge source of dispersal-mortality. Concentration flight: Provides a beacon to the formerly-dispersing beetles. Ends a major source of population mortality. Even dumb beetles survive when their sense the aggregant. Thoughts on Dispersal & Concentration Flights.

10. When the MPB population is low the host selection flight is desperately important in finding these scattered hosts. Remember there are few scattered focus trees across the landscape. Few MPB Latent Population

11. B.C. Long term drought pattern 2009 10yr October Drought Index of NOAA

12. As a drought continues, more and more trees are stressed and more focus trees are created. As more weakened trees are attacked, the higher goes the MPB population – exponentially!

13. “Once the population is high look out for the switching mechanism?”

14. When MPB population is high example A focus tree is attracting males and females via the pheromone cis- verbenol produced by attacking females. Host volatiles also play a role in the bouquet of attraction. But just at mating males produce the anti-aggregant, verbenone.

15. Hours/minutes Accumulative attack Focus tree Hundreds of males & females attacking the focus tree When the sexes are paired Time 1 The tree is no longer attractive. Time 2 Recipient tree Time 3 Neighboring tree is attacked

16. Spread of an MPB Spot in Lodgepole Pine: the switching mechanism. The formerly concentrating MPB, switch to the next largest tree(s) F R1R1 R2R2 R2R2 R3R3

17. More spread of an MPB-Lpp Spot: the switching mechanism continues and beetles keep on picking-off the biggest recipient tree. F1F1 R1R1 R2R2 R2R2 R3R3 F2F2 R2R2 R3R3

18. In lodgepole pine, why do the MPBs switch attacks to the largest recipient trees? The phloem of Lpp is thin! Whereas the phloem of ponderosa pine is thick.

19. During the first years of the outbreak the MPB population suffers “normal curve” mortality. All 98.8% 69.9% Tree DBH % Mortality Good Survival FrFr Why? Lodgepole pines have thin bark! The trees with small DBH have the thinnest phloem & highest brood mortality.

20. “…look at the variance.”

21. In lodgepole pine the MPBs that were concentrating on a focus tree switch their attacks to the next biggest recipient-tree. Ultimately they do a “diameter-limit cut.” Switching mechanism (continued) Meanwhile, the drought continues

22. (1)More and more focus trees & recipient trees are created: this increase is coupled with -- (2)Continuing use of the switching mechanism in host selection – less selection of the keenest beetles, (3)Switching behavior signifies more and more brood trees are established & MPB populations go even higher.

23. The drought continues! 2015

24. Myriad of focus trees across the watersheds right at the time beetles start to emerge in spring!

25. Early spring flight (…for whatever reason some emerge first.) Main spring flight Time (days) % Emergence

26. Flying Pop. Freshly attacked trees are common since they were infested by the small early emergence 1. Barley significant dispersal flight. Cis-verbenol Massive general spring emergence is pointed in the right direction and any tree is attacked. 1 Remember, lots of focus trees.

27. There is synchrony between MPB emergence and attraction to new pheromone source. There is no synchrony and MPB population disperses until susceptible hosts are found. Any Lpp Susceptible Lpp Concentration Dispersal Population Low High Huge outbreaks have a synchrony between spring emergence and aggregating pheromone

28. No Dispersal Just Synchrony Between Emergence and Aggregants – Any Pine Is Attacked Can you all see that inbreeding is rampant?

29. So where have we been in this discussion? Mountain Pine Beetle Outbreaks Population Characteristics Host Selection BehaviorStand/Host Conditions (1) Initial Phase Normal Dispersal flights Aggregant production Concentration flights Brood establishment 70-90 yrs old lodgepole – scattered drought stressed trees (focus trees) Stagnant growth (intra specific competition high) Fire exclusion for many yrs No silvicultural treatments Drought conditions continue (2) Tree to tree spread Normal Dispersal flights Aggregant production Concentration flights Brood establishment Switching behavior wide- spread 70-90 yr old trees in drought stress Focus trees wide-spread No fires and stand thinnings Drought continues Massive stand mortality (3) Population eruption No dispersal flights Aggregants in synchrony with emergence common Any tree attacked Population inbreeding occurs leading to population decline All 70-90 yr old trees in drought stress Focus trees ubiquitous Stand replacement fires possible Landscape-wide pine mortality Pine regeneration begins across landscape after outbreak and fires

30. “…ok, from the top.”

31. (1) The Initial Phase of a MPB Outbreak Host Selection - Normal - Dispersal flights - Aggregants produced - Concentration flights - Broods established Stand/Host Conditions - 70-90 yr old Lpp, scattered drought stressed focus trees - Stagnant growth (intra specific competition high) - Fire exclusion for many yrs - No silvicultural treatments - Drought continues Initial Phase

32. As a forest manager, now is the time to thin these stands!! Why? (1) to prevent the switching mechanism (2) to increase stand vigor and, ultimately, reduce numbers of focus trees and (3) to strategically use synthetic semiochemicals (attractants and repellants) Distance between focus tree and recipient tree needed to prevent the switching mechanism.

33. (2) Rapid Tree to Tree Spread Host Selection - Normal - Dispersal flights - Aggregants produced - Concentration flights - Broods established - Switching behavior wide spread! Stand/Host Conditions - 70-90 yr old Lpp, scattered drought stressed focus trees - Stagnant growth (intra specific competition high) - Fire exclusion for many yrs - No silvicultural treatments - Drought continues - Massive stand mortality begins! - Massive MPB population explosion begins! Rapid Spread Phase

34. What can you do? (1)Worry about stand replacement fires, (2)Salvage for income and fire prevention, (3)Thin drastically those stands as yet un-infested (4) Forget the use of synthetic attractants or repellents – big waste of money.

35. Synchrony of emergence & attraction begins – Wham!!

36. (3) MPB population eruption Host Selection - No dispersal flights - Aggregants in synch with with beetle emergence - Any tree attacked - Population inbreeding occurs leading to population decline. Stand/Host Conditions - 70-90 yr old Lpp, focus trees ubiquitous - Stand replacement fires common - Drought probably continues - Landscape mortality - Pine regeneration begins across landscape after outbreaks and fires. Eruption Phase

37. What can you do? (1) Pray for good mkt. in forest products. (2) Salvage

38. Don’t concern yourself about Lpp – it’ll take off on its own.

39. Don’t worry about the MPB population, it’ll crash on it’s own. 1.Inbreeding 2.Dumb beetles - few fat bodies - poor responders - infertile Why?

40. We’ve actually studied barkbeetles to prove that within any population there are dumb beetles. Dumb Beetles for

41. Attractive bait (log with beetles imbedded) Fan Jar One of a group of 3 olfactometers – used to collect attracted beetles: studies on Ips paraconfusus 05 25 45 etc. Concentric release pts. of 05m – 2k m …and we collected beetles from within an outbreak and from an endemic area.

42. 20 05 15 10 25 30 0 05 25 45 100 500 1K 2K %Recovery Distance to Olfactometer (m) Beetles from endemic area Beetles from outbreak area Test to see if beetles from an endemic area were better responders to attractants.

43. Freshly emerged Caught responding Beetle launcher 10m Olfactometer Emergence cage Logs infested with beetles about to emerge.

44. Responding beetles Emerging beetles No. of re-runs % Recovery Responding beetles Emerging beetles No. of re-reruns A test to shows that beetles who responded previously were better suited to find attractants

45. Highest Qual. Food Lower Qual. Food Low Qual. Food (Dry and fermenting) Days 84161220 % Of Logs Infested Lpp logs attacked by Ips spp. and quickly caged.

46. Release and response of barkbeetles that fed on high-qual. food. Release and response of barkbeetles that fed on low-qual. food. Release and response of barkbeetles that fed on awful-qual. food. A test showing how food quality affects the ability of barkbeetles to respond to attractants.

47. Some Conclusions on MPB Population Dynamics When populations are latent, there is strong selection for the keenest beetles – strong flyers and response to host and pheromone plumes over long distances is the selection mechanism. There is a huge dispersal loss and only keenest survive. Population as well as individuals are tied in to the condition of the hosts – focus trees are stressed trees and many focus trees spells the beginning of population increase. Countless focus trees across the landscape ultimately eliminates the flight dispersal and selection of keen beetles as well as there is an increase in inbreeding -- all important causes of population collapse. Massive reduction in the quality of the MPB population and lack of host material is the end of the outbreak.

48. Outbreak collapse is due to lack of synchrony between spring emergence & response to volatile cues. Which, in turn, is due to lack of nearby susceptible host material. Any Lpp Susceptible Lpp Concentration Dispersal Population Low High No hosts nearby Pop. poor quality Residual MPB pop. is seed corn for next latent pop.

49. Initial Phase of MPB build up 1.Thinning is mandatory before many focus trees are created. 2. Use of synthetic attractants and repellents should be studied. - confusion technique - push-pull studies - trapping 3. Bring back fire into the ecosystem. As Forest Managers, What Do We Do?

50. Silvicultural studies in the South clearly show there is no control during the eruptive phase of a SPB outbreak. Makes sense

51. Thinning southern pines Thinning lodgepole pine

52. Bring fire back into the silvicultural equation

53. Well, I see it’s time to quit.