Mountain pine beetle (Dendroctonus ponderosae) can produce its aggregation pheromone and complete brood development in naïve red pine (Pinus resinosa) under laboratory conditions (original) (raw)
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Environmental Entomology, 2008
Subtle differences in pheromone components of sympatric species should be attractive only to the producing species and unattractive or repellent to the nonproducing species, and thereby maintain reproductive isolation and reduce competition between species. Bark beetles Dendroctonus brevicomis and D. frontalis (Coleoptera: Curculionidae) are known to have common pheromone components, except for exo-brevicomin, which is produced by D. brevicomis. We predicted that D. frontalis would not respond to exo-brevicomin outside of the zone of sympatry with D. brevicomis. We conducted a Þeld experiment to determine the effect of exo-brevicomin on attraction of D. frontalis and associated species in Mississippi. We determined whether D. frontalis pheromone production differed inside and outside the sympatric zone and compared the pheromone proÞles with D. brevicomis within the sympatric zone. Trapping studies revealed that D. frontalis can perceive and respond positively to exo-brevicomin, an aggregation pheromone of a sympatric congener (D. brevicomis), at locations hundreds of kilometers outside the sympatric zone. Qualitative pheromone proÞles showed that both species emit similar pheromone components: frontalin, endo-brevicomin, exobrevicomin, trans-verbenol, verbenone, and myrtenol. Although not previously reported, D. frontalis males from Arizona produced exo-brevicomin. The predator Thanasimus dubius did not discriminate traps baited with exo-brevicomin and was most attracted to traps with frontalin. Hylastes beetles were signiÞcantly attracted to traps baited with exo-brevicomin in combination with other compounds. Our results raise new practical and evolutionary questions on the role of exo-brevicomin in the behavioral ecology of D. frontalis. The addition of exo-brevicomin to the current lure might increase the efÞciency of trapping programs in the southeastern United States. KEY WORDS pheromones, interspeciÞc communication, reproductive isolation, exo-brevicomin, trapping Pheromone-mediated communication in bark beetles (Coleoptera: Curculionidae: Scolytinae) enables host and mate location, aggregation, and resource partitioning (Wood D. L. 1982, Borden et al. 1986, Byers 2004). InterspeciÞc interactions occur when het-erospeciÞc beetles (Svihra et al. 1980), predators (Byers et al. 1984, Reeve 1997), and parasitoids cue into a colonized resource (Ayres et al. 2001, Dahlsten et al. 2004) that is usually rare or patchy in distribution. When two or more species are sympatric and inhabit the same tree, pheromones serve to partition the resource and minimize the deleterious effects of inter-speciÞc competition (Byers and Wood 1980, 1981, Light et al. 1983, Rankin and Borden 1991) by maintaining adequate spacing among galleries. The genus Dendroctonus includes major killers of pine trees that often occur in outbreaks, during which they can overcome and kill healthy trees (Wood S. L. 1982). Females initiate attack, excavate galleries in the phloem, and release aggregation pheromones that are attractive to both sexes (Borden et al. 1986, Raffa et al. 1993). In most Dendroctonus species, females are joined by males that may also produce aggregation pheromones that further facilitate aggregation. Successful colonization and reproduction by beetles in living trees thus requires release of enough aggregation pheromone to ensure the attraction of sufÞcient conspeciÞcs to overwhelm host defenses (Raffa et al. 1993). Many bark beetle species have common pheromone components, although the sex that produces them and their function varies. For example, frontalin is the female-produced aggregation pheromone in the southern pine beetle, D. frontalis (Kinzer et al. 1969, Renwick and Vité 1969), the Douglas-Þr beetle, D.
Environmental Entomology, 2008
Subtle differences in pheromone components of sympatric species should be attractive only to the producing species and unattractive or repellent to the nonproducing species, and thereby maintain reproductive isolation and reduce competition between species. Bark beetles Dendroctonus brevicomis and D. frontalis (Coleoptera: Curculionidae) are known to have common pheromone components, except for exo-brevicomin, which is produced by D. brevicomis. We predicted that D. frontalis would not respond to exo-brevicomin outside of the zone of sympatry with D. brevicomis. We conducted a field experiment to determine the effect of e:w-brevicomin on attraction of D. frontalis and associated species in Mississippi. We determined whether D. frontalis pheromone production differed inside and outside the sympatric zone and compared the pheromone profiles with D. brevicomis within the sympatric zone. Trapping studies revealed that D. frontalis can perceive and respond positively to exo-brevicomin, an aggregation pheromone of a sympatric congener (D. brevicomis) , at locations hundreds of kilometers outside the sympatric zone. Qualitative pheromone profiles showed that both species emit similar pheromone components: frontalin, endo-brevicomin, exobrevicomin, trans-verbenol, verbenone, and myrtenol. Although not previously reported, D. frontalis males from Arizona produced exo-brevicomin. The predator Thanasimus dubius did not discriminate traps baited with exo-brevicomin and was most attracted to traps with frontalin. Hylastes beetles were significantly attracted to traps baited with exo-brevicomin in combination with other compounds. Our results raise new practical and evolutionary questions on the role of exo-brevicomin in the behavioral ecology of D. frontalis. The addition of exo-brevicomin to the current lure might increase the efficiency of trapping programs in the southeastern United States. KEY WORDS pheromones, interspecific communication, reproductive isolation, exo-brevicomin, trapping Pheromone-mediated communication in bark beetles (Coleoptera: Curculionidae: Scolytinae) enables host and mate location, aggregation, and resource partitioning (Wood D. L 1982, Borden et al. 1986, Byers 2004). Interspecific interactions occur when heterospecific beetles (Svihra et al. 1980), predators (Byers et al. 1984, Reeve 1997), and parasitoids cue into a colonized resource (Ayres et al. 2001, Dahlsten et al. 2004) that is usually rare or patchy in distribution. When two or more species are sympatric and inhabit the same tree, pheromones serve to partition the re~ source and minimize the deleterious effects of interspecific competition (Byers and Wood 1980, 1981,
2015
The secondary compounds of pines (Pinus) can strongly affect the physiology, ecology and behaviour of bark beetles (Coleoptera: Curculionidae, Scolytinae) that feed on host subcortical tissues. Jack pine (Pinus banksiana) has a wide distribution range in North America and thus variations in its secondary compounds, particularly monoterpenes, could affect the host expansion of mountain pine beetle (Dendroctonus ponderosae), which has recently attacked jack pine as a novel host and expanded its range into the boreal forest. I analyzed variations in monoterpene composition of jack pine foliage and phloem from natural and provenance stands representing populations from Alberta to the Atlantic coast. Additionally, the effects of variations in phloem monoterpene composition on pheromone production by mountain pine beetle were analyzed. Throughout its range, jack pine foliage monoterpenes were classified into three chemotypes characterized by high proportions of the monoterpenes α-pinene, β-pinene, or limonene. Expression of these chemotypes was controlled by both genetic and environmental factors and individual monoterpenes were correlated with climatic variables differently. Conversely, phloem monoterpenes were classified into groups characterized by high amounts of the monoterpenes (+)-α-pinene, 3-carene or no notably high individual compound and beetle aggregation and anti-aggregation pheromone production varied with these groups. Furthermore, pheromone production also varied between provinces, with the most aggregation pheromone produced in trees from Manitoba and Quebec. These results indicate that pheromone production by D. ponderosae will vary with host chemistry but remain a viable and important aspect of its survival and persistence in the boreal forest. iii Preface This document presents two studies (Chapters 2 and 3) intended for publication and represent collaborative work led by Dr Nadir Erbilgin of the University of Alberta. I was responsible for data collection and analyses, literature review and manuscript composition and writing throughout this document. Dr Erbigin was involved with concept formation and manuscript composition throughout the work. Additionally, Ahmed Najar of the University of Alberta was responsible for developing chemical analyses described in Chapters 2 and 3. For Chapter 2, Drs Jean Bousquet and Julie Godbout of Université Laval carried out field work and provided samples and manuscript edits. All research presented in this thesis was conducted in accordance with all applicable laws and rules set forth by provincial and federal governments and the U of A and all necessary permits were in hand when the research was conducted.
The Canadian Entomologist, 2014
The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), outbreak in British Columbia and Alberta, Canada, currently extends over 18.3 million ha of pine forest. The principal host of the insect is lodgepole pine, Pinus contorta var. latifolia Englemann (Pineaceae) although it is a generalist herbivore on pines. Mountain pine beetles do not typically colonise spruce. However, during the current outbreak, several instances of mountain pine beetle attack on interior hybrid spruce, Picea glauca (Moench) Voss×Picea engelmannii Parry ex. Engelmann (Pinaceae) have been noted in areas where severe lodgepole pine mortality has occurred. Occasionally, beetle reproduction within spruce has been successful. Reproductive behaviours of mountain pine beetles reared from pine and spruce, such as female host acceptance and male joining behaviour, were studied on bolts of pine and spruce in laboratory bioassays. Females more readily accepted spruce host material relativ...
Dose-Dependent Pheromone Responses of Mountain Pine Beetle in Stands of Lodgepole Pine
Environmental Entomology, 2005
We conducted seven behavioral choice tests with Lindgren multiple-funnel traps in stands of mature lodgepole pine in British Columbia, from 1988 to 1994, to determine the dosedependent responses of the mountain pine beetle, Dendroctonus ponderosae Hopkins, to its pheromones. A multifunctional dose-dependent response was exhibited by D. ponderosae to the pheromones cisand trans-verbenol in areas with low population numbers. In an area with a high population level of D. ponderosae, the response was directly proportional to release rates. No dose-dependent response was exhibited by D. ponderosae to exo-brevicomin at low release rates. At rates of release Ͼ0.5 mg/d, exo-brevicomin interrupted the attraction of D. ponderosae in a dose-dependent fashion. The bark beetle predators, Enoclerus sphegeus (F.) and Thanasimus undatulus (Say), showed dose-dependent responses to only a few pheromones, with trap catches directly proportional to release rates. The multi-functional response of D. ponderosae to verbenols is consistent with an optimal attack density hypothesis.
Agricultural and Forest Entomology, 2015
Mountain pine beetle (Dendroctonus ponderosae) is an important disturbance agent in Pinus ecosystems of western North America, historically causing significant tree mortality. Most recorded outbreaks have occurred in mid elevation lodgepole pine (Pinus contorta). In warm years, tree mortality also occurs at higher elevations in mixed species stands. 2 Mountain pine beetle's relative preference for and performance in Pinus species that either commonly or less frequently encounter this insect has received little direct testing. Further, knowledge of the relative proportions of secondary compounds, which can differ among Pinus species and play important roles in attack rates and outcomes, is important to understanding host suitability. 3 We monitored mountain pine beetle attacks, adult emergence timing and reproductive capacity in lodgepole and whitebark (Pinus albicaulis) pines growing in mixed stands at relatively high elevation. Phloem monoterpene chemistry of trees prior to and during attack was compared within and between species. 4 Although beetles attacked lodgepole pine more frequently, lodgepole pines also resisted attacks more frequently. Overall, there were equal numbers of lethal attacks between species. Brood production and adult emergence timing did not differ between tree species. 5 The relative composition of secondary compounds differed by tree species, although both species contained compounds that affect mountain pine beetle attack and reproductive success.
Forest Ecology and Management, 2020
Mountain pine beetle has expanded its host range into naïve lodgepole pine forests in western Canada and killed a large number of pine trees. Synthetic attractants mainly bark beetle pheromones and host monoterpenes attached to traps are typically used to monitor beetle populations within its range. Despite well-established differences in beetle host selection behavior between endemic and outbreak population densities, the influence of population density on the response of mountain pine beetle to the synthetic attractants is poorly understood. Over three years, we tested the effects of different release rates of female mountain pine beetle aggregation pheromone (trans-verbenol) and two host monoterpenes (terpinolene and mycrene) and local beetle population density on trap catches of mountain pine beetle. We estimated local mountain pine beetle population densities using the number of dead trees observed in the previous year's aerial detection survey. During the first three weeks of the flight period, the lures with low release rates of all components captured more mountain pine beetle with increasing beetle population density and the lures with a high release rate of trans-verbenol plus a low release rate of host monoterpenes were preferred by beetles in low population density sites. We also found a temporal shift in attraction patterns. As the flight period progressed, the preference for low trans-verbenol release rate lures was less pronounced at high mountain pine beetle densities. No sex-specific responses of mountain pine beetles, along with number of competitor and predatory beetles of mountain pine beetle, were found for a particular attractant. These results provide evidence that mountain pine beetle has a density dependent response to attractants and can assess available semiochemicals cues to ensure successful host colonization depending on their density and the flight period. Overall, this study can improve the efficacy of current semiochemical-based monitoring tools, which are essential to implementing informed mitigation strategies for mountain pine beetle especially while they are in a sub-outbreak stage in the expanded distribution.
Forest Ecology and Management, 2019
Introductions of alien forest insects can exert substantial ecological and economic impacts on natural forest systems. The mountain pine beetle, Dendroctonus ponderosae Hopkins, an aggressive bark beetle native to western North America, kills mature pines at outbreak levels and is currently expanding its geographic, altitudinal and host ranges across the continent. Its oligophagous feeding behavior and its ability to kill novel hosts in newly invaded areas of Alberta, Canada suggest that this insect could threaten pine forests in other regions of the world. Little is known of the susceptibility of Scots pine, Pinus sylvestris L., to mountain pine beetle. Scots pine is a potential novel host common to forests across Eurasia and introduced to North America. Laboratory studies indicate the insects can colonize and reproduce in harvested logs of the host. We measured outcomes of an outbreak by mountain pine beetle in mixed stands of mature Scots pine and ponderosa pine, P. ponderosa Dougl. ex. Laws. var. scopulorum Engelm., a historical host for the insect, in the Black Hills of South Dakota, U.S.A. We conducted a retrospective assessment of beetle attack and tree mortality of 165 trees (54 Scots pine and 111 ponderosa pine) of similar size and proximity that experienced high beetle pressure for three to four years ending in 2015. Our results show that mountain pine beetle can detect and attack live trees of Scots pine. Notably, we found that nearly 90% of Scots pines showed signs of attack, while no evidence of attack was found on the historical host in mixed stands. However, we found that Scots pines received half the attack density and demonstrated fifteen fold less likelihood of mortality in one year's time relative to ponderosa pine in nearby stands. These results are important for assessing the potential for mountain pine beetle to kill trees in Eurasia and North America in Scots pine stands.
Forests
The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), recently underwent a notable range-expansion event in western Canada, resulting in access to the novel host jack pine, Pinus banksiana Lamb. We assessed the suitability of jack pine for mountain pine beetle, as well as the historic host lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm., and the non-Pinus host white spruce, Picea glauca (Moench) Voss, to help inform an assessment of the risk of future spread into Canada’s boreal forest and to further our understanding of host use in bark beetles. Several performance traits we measured were similar between lodgepole pine and jack pine, but gallery length and productivity indicated that lodgepole pine was the more suitable host. Development appeared to be faster in jack pine; however, in contrast to previous studies, we attribute it to oviposition arresting earlier in the novel host compared to the other hosts and not a difference in devel...