@article {13301,
	title = {Population dynamics in changing environments: the case of an eruptive forest pest species},
	journal = {Biological Reviews (Cambridge)},
	volume = {87},
	number = {1},
	year = {2012},
	month = {Feb},
	pages = {34-51},
	abstract = {In recent decades we have seen rapid and co-occurring changes in landscape structure, species distributions and even climate as consequences of human activity. Such changes affect the dynamics of the interaction between major forest pest species, such as bark beetles (Coleoptera: Curculionidae, Scolytinae), and their host trees. Normally breeding mostly in broken or severely stressed spruce; at high population densities some bark beetle species can colonise and kill healthy trees on scales ranging from single trees in a stand to multi-annual landscape-wide outbreaks. In Eurasia, the largest outbreaks are caused by the spruce bark beetle, Ips typographus (Linnaeus), which is common and shares a wide distribution with its main host, Norway spruce (Picea abies Karst.). A large literature is now available, from which this review aims to synthesize research relevant for the population dynamics of I. typographus and co-occurring species under changing conditions. We find that spruce bark beetle population dynamics tend to be metastable, but that mixed-species and age-heterogeneous forests with good site-matching tend to be less susceptible to large-scale outbreaks. While large accumulations of logs should be removed and/or debarked before the next swarming period, intensive removal of all coarse dead wood may be counterproductive, as it reduces the diversity of predators that in some areas may play a role in keeping I. typographus populations below the outbreak threshold, and sanitary logging frequently causes edge effects and root damage, reducing the resistance of remaining trees. It is very hard to predict the outcome of interspecific interactions due to invading beetle species or I. typographus establishing outside its current range, as they can be of varying sign and strength and may fluctuate depending on environmental factors and population phase. Most research indicates that beetle outbreaks will increase in frequency and magnitude as temperature, wind speed and precipitation variability increases, and that mitigating forestry practices should be adopted as soon as possible considering the time lags involved.},
	keywords = {Scolytinae},
	isbn = {1464-7931},
	author = {Kausrud, Kyrre and Okland, Bjorn and Skarpaas, Olav and Gregoire, Jean-Claude and Erbilgin, Nadir and Stenseth, Nils Chr}
}
@article {10877,
	title = {A host monoterpene influences Ips typographus (Coleoptera: Curculionidae, Scolytinae) responses to its aggregation pheromone},
	journal = {Agricultural and Forest Entomology},
	volume = {9},
	number = {2},
	year = {2007},
	month = {May},
	pages = {135-140},
	abstract = {1 Host tree terpenes can influence attraction of conifer-infesting bark beetles to their aggregation pheromones, and both synergistic and inhibitory effects have been reported. 2 We tested a gradient of ratios of (-)-a-pinene, the predominant monoterpene in Norway spruce, to the pheromone of Ips typographus, a major pest of Norway spruce. 3 Attraction of I. typographus increased as the release rate of (-)-a-pinene increased. The two highest (-)-a-pinene : pheromone ratios (526 : 1 and 2595 : 1) attracted twice as many I. typographus as pheromone alone, whereas low to intermediate ratios (56 : 1, 274 : 1) did not differ from pheromone alone. 4 Our results are in agreement with a proposed model, which suggests that bark beetles display unique response profiles to host terpenes depending on the physiological condition of the host trees that they typically colonize. Ips typographus, which is an aggressive species capable of colonizing and killing healthy trees, showed an increased attraction to monoterpene : pheromone ratios, and this may be high enough to inhibit attraction of less aggressive beetle species typically colonizing dead, dying or stressed trees. 5 Attraction of associates of I. typographus was also modified by (-)-a-pinene. Ips duplicatus, a competitor of I. typographus, showed increased attraction to the pheromone of I. typographus across all concentrations of (-)-a-pinene},
	keywords = {Ips typographus},
	isbn = {1461-9555},
	author = {Erbilgin, Nadir and Krokene, Pal and Kvamme, Torstein and Christiansen, Erik}
}
@article {10873,
	title = {Acetophenone superior to verbenone for reducing attraction of western pine beetle Dendroctonus brevicomis to its aggregation pheromone},
	journal = {Agricultural and Forest Entomology},
	volume = {10},
	number = {4},
	year = {2008},
	month = {November},
	pages = {433-441},
	type = {Article},
	abstract = {1 The western pine beetle Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae) is one of the most damaging insect pests of ponderosa pines Pinus ponderosa Douglas ex P. \& C. Lawson in Western U.S.A. We compared the effect of verbenone, a well known bark beetle anti-aggregation pheromone, with that of acetophenone on the attraction of D. brevicomis to its aggregation pheromone in a ponderosa pine forest in northern California. We tested the D. brevicomis aggregation pheromone alone and with three different release ratios of the aggregation pheromone (attractant) to verbenone or acetophenone (1 : 1, 1 : 2 and 1 : 5).2 All treatments containing acetophenone or verbenone resulted in a significant reduction in the catch of D. brevicomis relative to the aggregation pheromone alone. When beetle responses to the three verbenone or three acetophenone treatments were pooled, the pooled verbenone treatment caught more D. brevicomis than the pooled acetophenone treatment.3 There was no significant difference in the number of D. brevicomis caught among the three release rates of verbenone. By contrast, the 1 : 2 attractant : acetophenone ratio attracted significantly more D. brevicomis than the traps with the 1 : 5 attractant : acetophenone ratio.4 Attraction of a major predator, Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae), to the aggregation pheromone of D. brevicomis was reduced by verbenone, but not by acetophenone. Moreover, the T. chlorodia : D. brevicomis ratio for the pooled acetophenone treatment was 1.7-fold greater than that for the attractant alone and two-fold greater than the ratio for the pooled verbenone treatment, suggesting that acetophenone would not disrupt populations of this natural enemy. The importance of anti-attractants in the biology of D. brevicomis and other bark beetles is discussed.},
	keywords = {Dendroctonus brevicomis},
	isbn = {1461-9555},
	author = {Erbilgin, Nadir and Gillette, Nancy E. and Owen, Donald R. and Mori, Sylvia R. and Nelson, Andrew S. and Uzoh, Fabian and Wood, David L.}
}
@article {10874,
	title = {Bark beetle-mediated fungal infections of susceptible trees induce resistance to subsequent infections in a dose dependent manner},
	journal = {Agricultural and Forest Entomology},
	volume = {11},
	number = {3},
	year = {2009},
	month = {August},
	pages = {255-263},
	abstract = {1 Experiments were conducted to determine whether propagule loads on the twig beetles Pityophthorus setosus and Pityophthorus carmeli (Coleoptera: Scolytidae) influence the pathogen infection of the host tree in the Monterey pine-Fusarium circinatum system.2 On an average, F. circinatum was isolated from 2.6\% and 3.3\% of trapped P. setosus and P. carmeli, respectively, although the isolation percentages varied over the season, being highest in the spring and lowest in late summer and fall for both species. Mean pathogen load was 13.4 and 22.6 propagules per beetle, on P. setosus and P. carmeli, respectively, and decreased from May to November for both species. The pathogen was also isolated from approximately 55\% of both beetle species that emerged from infected branches. Mean propagule load on emerged P. setosus and P. carmeli was 39 and 66.5, respectively.3 On the basis of these data, beetle species were treated with one of three propagule loads (low, medium, high) and caged onto live branches to determine whether they could transmit the pathogen. At all propagule loads, both species transmitted the pathogen, and transmission percentage and lesion length, a measure of tree susceptibility, were positively correlated with propagule load.4 To investigate further whether the previous transmission by beetles could affect response of the same trees to subsequent infection with F. circinatum, different branches were inoculated on the same trees used in the transmission study, and lesion lengths were measured. Lesion lengths were lower on trees that had been previously exposed to beetles treated with high or medium propagule loads than on trees that had previously been exposed to beetles treated with low propagule loads. This suggests that the initial infection by beetles carrying high or medium propagule loads induced resistance to subsequent infections of the host, whereas infections caused by beetles with low propagule loads did not.},
	keywords = {Pityophthorus carmeli, Pityophthorus setosus},
	isbn = {1461-9555},
	author = {Erbilgin, Nadir and Gordon, Thomas R. and Wood, David L. and Storer, Andrew J.}
}
@article {10084,
	title = {Tree-mediated interactions between the jack pine budworm and a mountain pine beetle fungal associate},
	journal = {Ecological Entomology},
	volume = {36},
	number = {4},
	year = {2011},
	month = {Aug},
	pages = {425-434},
	abstract = {1. Coniferous trees deploy a combination of constitutive (pre-existing) and induced (post-invasion), structural and biochemical defences against invaders. Induced responses can also alter host suitability for other organisms sharing the same host, which may result in indirect, plant-mediated interactions between different species of attacking organisms. 2. Current range and host expansion of the mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) from lodgepole pine-dominated forests to the jack pine-dominated boreal forests provides a unique opportunity to investigate whether the colonisation of jack pine (Pinus banksiana Lamb.) by MPB will be affected by induced responses of jack pine to a native herbaceous insect species: the jack pine budworm (Choristoneura pinus pinus Freeman; JPBW). 3. We simulated MPB attacks with one of its fungal associates, Grosmannia clavigera Robinson-Jeffrey \& Davidson, and tested induction of either herbivory by JPBW or inoculation with the fungus followed by a challenge treatment with the other organism on jack pine seedlings and measured and compared monoterpene responses in needles. 4. There was clear evidence of an increase in jack pine resistance to G. clavigera with previous herbivory, indicated by smaller lesions in response to fungal inoculations. In contrast, although needle monoterpenes greatly increased after G. clavigera inoculation and continued to increase during the herbivory challenge, JPBW growth was not affected, but JPBW increased the feeding rate to possibly compensate for altered host quality. 5. Jack pine responses varied greatly and depended on whether seedlings were treated with single or multiple organisms, and their order of damage.},
	keywords = {Dendroctonus ponderosae},
	isbn = {0307-6946},
	author = {Colgan, Lindsay J. and Erbilgin, Nadir}
}
@article {8554,
	title = {Role of stressed mango host conditions in attraction of and colonization by the mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Curculionidae: Scolytinae) and in the symptom development of quick decline of mango trees in Pakistan},
	journal = {Entomological Research (Seoul)},
	volume = {40},
	number = {6},
	year = {2010},
	month = {Nov},
	pages = {316-327},
	abstract = {The mango sudden death syndrome has become a serious threat to the mango industry and caused significant decline in mango production worldwide. The bark beetle Hypocryphalus mangiferae (Stebbing) (Coleoptera: Curculionidae: Scolytinae) has been suggested as a potential vector of the disease based primarily on field observations with little or no supporting empirical data. In this study, we investigated the role of infected mango trees in host attraction and colonization by H. mangiferae to determine if beetle attack and colonization contributes to the disease progression on mango trees. Initially, the role of various stress factors on beetle attraction and disease progression was assessed under lathe house conditions from 2008 to 2009. Results suggest that symptomatic or recently inoculated mango trees (without any obvious symptoms) are preferentially colonized by H. mangiferae. Although not significant, high numbers of beetles attacked stressed or wounded mango trees, compared to healthy or dead mango trees. Disease symptoms after beetle colonization, such as bark splitting, wilting and oozing, were further evaluated. These symptoms showed positive correlation with the degree of disease severity and host plant condition. Furthermore, two fungi, Ceratocystis fimbriata and Lasiodiplodia theobromae, were frequently isolated from the beetle and beetle-colonized trees. Based on these findings, they suggests that H. mangiferae can vector multiple fungi associated with mango sudden decline disease and play a significant role in outbreaks of this disease.},
	keywords = {Hypocryphalus mangiferae},
	isbn = {1738-2297},
	author = {Masood, Asad and Saeed, Shafqat and Erbilgin, Nadir and Kwon, Yong Jung}
}
@article {6000,
	title = {Host resistance elicited by methyl jasmonate reduces emission of aggregation pheromones by the spruce bark beetle, Ips typographus},
	journal = {Oecologia (Berlin)},
	volume = {167},
	number = {3},
	year = {2011},
	month = {Nov},
	pages = {691-699},
	abstract = {We treated Norway spruce (Picea abies) stems with methyl jasmonate (MeJA) to determine possible quantitative and qualitative effects of induced tree defenses on pheromone emission by the spruce bark beetle Ips typographus. We measured the amounts of 2-methyl-3-buten-2-ol and (S)-cis-verbenol, the two main components of the beetle{\textquoteright}s aggregation pheromone, released from beetle entrance holes, along with phloem terpene content and beetle performance in MeJA-treated and untreated Norway spruce logs. As expected, phloem terpene levels were higher and beetle tunnel length was shorter (an indication of poor performance) in MeJA-treated logs relative to untreated logs. Parallel to the higher phloem terpene content and poorer beetle performance, beetles in MeJA-treated logs released significantly less 2-methyl-3-buten-2-ol and (S)-cis-verbenol, and the ratio between the two pheromone components was significantly altered. These results suggest that host resistance elicited by MeJA application reduces pheromone emission by I. typographus and alters the critical ratio between the two main pheromone components needed to elicit aggregation. The results also provide a mechanistic explanation for the reduced performance and attractivity observed in earlier studies when bark beetles colonize trees with elicited host defenses, and extend our understanding of the ecological functions of conifer resistance against bark beetles.},
	keywords = {Ips typographus},
	isbn = {0029-8549},
	author = {Zhao, Tao and Borg-Karlson, Anna-Karin and Erbilgin, Nadir and Krokene, Paal}
}
@article {5521,
	title = {Trees Wanted-Dead or Alive! Host Selection and Population Dynamics in Tree-Killing Bark Beetles},
	journal = {Plos One},
	volume = {6},
	number = {5},
	year = {2011},
	month = {2011},
	pages = {e18274, 1-13},
	abstract = {Bark beetles (Coleoptera: Curculionidae, Scolytinae) feed and breed in dead or severely weakened host trees. When their population densities are high, some species aggregate on healthy host trees so that their defences may be exhausted and the inner bark successfully colonized, killing the tree in the process. Here we investigate under what conditions participating with unrelated conspecifics in risky mass attacks on living trees is an adaptive strategy, and what this can tell us about bark beetle outbreak dynamics. We find that the outcome of individual host selection may deviate from the ideal free distribution in a way that facilitates the emergence of tree-killing (aggressive) behavior, and that any heritability on traits governing aggressiveness seems likely to exist in a state of flux or cycles consistent with variability observed in natural populations. This may have implications for how economically and ecologically important species respond to environmental changes in climate and landscape (forest) structure. The population dynamics emerging from individual behavior are complex, capable of switching between {\textquoteright}{\textquoteright}endemic{\textquoteright}{\textquoteright} and {\textquoteright}{\textquoteright}epidemic{\textquoteright}{\textquoteright} regimes spontaneously or following changes in host availability or resistance. Model predictions are compared to empirical observations, and we identify some factors determining the occurrence and self-limitation of epidemics.},
	keywords = {Scolytinae},
	isbn = {1932-6203},
	url = {http://ukpmc.ac.uk/issues/116071/},
	author = {Kausrud, Kyrre L. and Gregoire, Jean-Claude and Skarpaas, Olav and Erbilgin, Nadir and Gilbert, Marius and Okland, Bjorn and Stenseth, Nils Chr}
}
