Suitability of some southern and western pines as hosts for the pine shoot beetle, Tomicus piniperda (Coleoptera: Scolytidae)

The pine shoot beetle, Tomicus piniperda (L.), is an exotic pest that has become established in North America. Discovered in Ohio in 1992, it has since been found in at least 13 states and parts of Canada. The beetle can cause significant growth loss in pines, and it represents a potential threat to trees in areas where it has not yet become established. To evaluate this threat to native pines, field and laboratory tests were conducted on several common and important southern and western species to determine whether they are acceptable hosts for T. piniperda. Comparisons with Pinus sylvestris L., Scots pine, a preferred natural host for the beetle, were made where possible. Measurements of beetle attack success on southern pine billets showed that Pinus taeda L., Pinus echinata Miller, Pinus elliottii var. elliottii Engelmann, Pinus palustris Miller, and Pinus virginiana Miller (loblolly, shortleaf, slash, longleaf, and Virginia pine, respectively) and two western pines, Pinus ponderosa Lawson and Pinus contorta Douglas (ponderosa and lodgepole pine, respectively), were acceptable for breeding material, but brood production was highly variable. Among the southern pines, P. taeda and P. echinata were susceptible to shoot feeding by T. piniperda, whereas P. elliottii was highly resistant and P. palustris seemed to be virtually immune. Shoot feeding tests on the western pines were conducted only in the laboratory, but there was moderate-to-good survival of adults feeding on both species. It seems that if T. piniperda is introduced into the south and west it will likely establish and may cause some damage to native pines. P. taeda may be affected more than other southern pines because it is the most abundant species, it is readily attacked for brood production, which can result in moderately large broods, and the beetle survives well during maturation feeding on P. taeda shoots.     

Acceptance and suitability of novel trees for <Emphasis Type="Italic">Orthotomicus erosus</Emphasis>, an exotic bark beetle in North America

To predict whether an herbivorous pest insect will establish in a new area, the potential host plants must be known. For invading bark beetles, adults must recognize and accept trees suitable for larval development. The preference-performance hypothesis predicts that adults will select host species that maximize the fitness of their offspring. We tested five species of North American conifers and one angiosperm for adult acceptance and suitability for reproduction of the Mediterranean pine engraver, Orthotomicus erosus (Wollaston). Red pine, Pinus resinosa Aiton, and white spruce, Picea glauca (Moench) Voss, were accepted by adult beetles and suitable for reproduction to the extent of adult replacement. Others, such as balsam fir, Abies balsamea (L.) Mill., eastern hemlock, Tsuga canagensis (L.) Carrière, and tamarack, Larix laricina (Du Roi) Koch, were acceptable but unsuitable. The presence of tree species that are acceptable to adults but unsuitable for reproduction may affect the ability of O. erosus to establish across North America.     

An RFLP linkage map for loblolly pine based on a three-generation outbred pedigree

A genetic linkage map for loblolly pine (Pinus taeda L.) was constructed using segregation data from a three-generation outbred pedigree consisting of four grandparents, two parents, and 95 F₂ progeny. The map was based predominantly on restriction fragment length polymorphism (RFLP) loci detected by cDNA probes. Sixty-five cDNA and three genomic DNA probes revealed 90 RFLP loci. Six polymorphic isozyme loci were also scored. One-fourth (24%) of the cDNA probes detected more than 1 segregating locus, an indication that multigene families are common in pines. As many as six alleles were observed at a single segregating locus among grandparents and it was not unusual for the progeny to segregate for three or four alleles per locus. Multipoint linkage analysis placed 73 RFLP and 2 isozyme loci into 20 linkage groups; the remaining 17 RFLP and 4 isozyme loci were unlinked. The mapped RFLP probes provide a new set of codominant markers for genetic analyses in loblolly pine.     

Comparing the influences of ecological and evolutionary factors on the successful invasion of a fungal forest pathogen

The fungal forest pathogen Heterobasidion annosum has been introduced from North America into Italy and is now associated with high mortality of Italian stone pines. Due to the presence of a closely related native H. annosum taxon, this pathosystem presents an unusual opportunity to test specific ecological and evolutionary factors influencing fungal invasions. Comparative inoculation experiments on Scots pine cuttings and on seedlings of European and North American pines failed to identify significant increased pathogenicity of North American genotypes on European hosts congruent with lack of host-pathogen co-evolution. However, spore trappings indicate that while reproductive potential of native H. annosum was significantly reduced in the dry season, that of the invasive taxon was consistently high regardless of season. Ecological differences between the native and exotic taxon may therefore facilitate this invasion. Understanding which factors enhance this emerging forest disease is important both for biotic invasion theory and for disease control.     

萧氏松茎象危害与松树松脂量关系研究初报

萧氏松茎象HylobitelusxiaoiZhang是近年来暴发性松树害虫 ,主要危害 3种松树 :湿地松 (PinuselliottiiEngelm)、火炬松 (P .taeda)、马尾松 (P .massoniaanaLamb) ,其中以湿地松受害最为严重。为明确萧氏松茎象的危害与松脂流量的关系 ,作者对萧氏松茎象危害前后 3种松树 (湿地松、马尾松、火炬松 )松脂流量变化进行了研究。结果显示 ,在松树受害植株和未受害植株间松脂总流量间存在一定差异 ,其中以马尾松松脂流量变化最大 ,对受害株和未受害株松脂流量t-测验 ,差异达到显著水平 ;而湿地松和火炬松松脂总流量在受害植株和未受害植株间没有显著差异。对上述 3种松树松脂流量随时序动态变化的分析显示 ,松脂流量在 1年中以 5月到 6月之间为松脂流量高峰期 ,此后逐渐下降 ,到 3月中旬以后松脂流量又开始上升。就松脂流量时序动态而言 ,萧氏松茎象为害对马尾松松脂流量影响最大 ,对其它2个松树影响不明显。另外 ,不同松树树种在松脂流量及其时序动态上也存在一定差异 ,其中以马尾松脂流量较高。     

The red turpentine beetle, <Emphasis Type="Italic">Dendroctonus valens</Emphasis> LeConte (Scolytidae): an exotic invasive pest of pine in China

An exotic invasive pest of pines, the red turpentine beetle, Dendroctonus valens LeConte (Scolytidae) (RTB), was first detected in Shanxi Province, northern China, in 1998 and started causing widespread tree mortality there in 1999. This outbreak continues and has spread to three adjacent provinces, causing unprecedented tree mortality. Although it is considered a minor pest of pines in North America, RTB has proven to be an aggressive and destructive pest of Pinus tabuliformis, China’s most widely planted pine species. The bionomics and occurrence, distribution, response to host volatiles, and host preference of this pine beetle in China are compared with what is known of the beetle in its native range in North America. Factors likely contributing to D. valens success in China and control of the beetle outbreak are discussed. (−)-β-pinene was shown to be the most attractive host volatile for D. valens from the Sierra Nevada of California, whereas 3-(+)-carene is the most attractive host volatile for beetles in China. Monocultures of Pinus tabuliformis, several consecutive years of drought conditions and warm winters have apparently factored D. valens invasion and establishment in China.     

Performance of the potentially invasive Siberian moth Dendrolimus superans sibiricus on coniferous species in Europe

1 The native range of the Siberian moth extends from the Pacific Ocean (Russian Far East, Japan and Northern Korea) across Siberia, Northern China and Mongolia to the Ural Mountains. At the beginning of the 21st Century, this species was documented west of the Ural Mountains in the Republic of Mari El, indicating range extension toward the west.
2 The Siberian moth has recently been suggested for regulation as a quarantine pest for European and Mediterranean Plant Protection Organization member countries. However, no specific report on European host plants for this pest has been published so far.
3 In the present study, larval host plant choice and performance was tested for the first time on coniferous tree species that are widely distributed and of commercial value in Europe.
4 Based on dual-choice tests on neonates and mortality, developmental duration and relative growth rates of the first- to sixth-instar larvae, we found European larch Larix decidua to be the most suitable host for the moth larvae, whereas European black pine Pinus nigra and Scots pine Pinus sylvestris were the poorest hosts. The remaining conifer species tested, European silver fir Abies alba , Nordmann fir Abies nordmanniana , and Norway spruce Picea abies , were intermediate host plants. Douglas-fir Pseudotsuga menziesii , originating from North America, was chosen by the larvae to the same extend as European larch, and was also highly suitable for larval development.
5 If the moth is introduced to European countries, it will become damaging in stands of European larch and Douglas-fir, mixed stands of fir and spruce; however, it will be less damaging in forests dominated by two-needle pines.
6 We predict that Dendrolimus superans sibiricus will be able to survive and develop on the main European coniferous tree species, including non-native coniferous tree species, resulting in severe damage to large areas of forests.     

Argentine ant invasion associated with loblolly pines in the southeastern United States: minimal impacts but seasonally sustained

Invasive ants are notorious for directly displacing native ant species. Although such impacts are associated with Argentine ant invasions (Linepithema humile) worldwide, impacts within natural habitat are less widely reported, particularly those affecting arboreal ant communities. Argentine ants were detected in North Carolina mixed pine-hardwood forest for the first time but were localized on and around loblolly pines (Pinus taeda), probably because of association with honeydew-producing Hemiptera. We explored the potential impacts of L. humile on arboreal and ground-foraging native ant species by comparing interspersed loblolly pines invaded and uninvaded by Argentine ants. Impacts on native ants were assessed monthly over 1 yr by counting ants in foraging trails on pine trunks and in surrounding plots using a concentric arrangement of pitfall traps at 1, 2, and 3 m from the base of each tree. Of floristics and habitat variables, higher soil moisture in invaded plots was the only difference between plot types, increasing confidence that any ant community differences were caused by Argentine ants. Overall patterns of impact were weak. Composition differed significantly between Argentine ant invaded and uninvaded trunks and pitfalls but was driven only by the presence of Argentine ants rather than any resulting compositional change in native ant species. Native ant abundance and richness were similarly unaffected by L. humile. However, the abundance of individual ant species was more variable. Although numbers of the arboreal Crematogaster ashmeadi (Myrmicinae) declined on and around invaded pines, epigeic Aphaenogaster rudis (Myrmicinae) remained the most abundant species in all plots. Argentine ant densities peaked in late summer and fall, therefore overlapping with most native ants. Unexpected was their continued presence during even the coldest months. We provide evidence that Argentine ants can invade and persist in native North Carolina forests, probably mediated by pine-associated resources. However, their localized distribution and minimal impact on the native ant fauna relative to previously described invasions requires further resolution.     

Beneath the bark: associations among Sirex noctilio development,bluestain fungi,and pine host species in North America

1. Invasive species with global distributions encounter unique environmental and biotic variables that can greatly affect the magnitude of their impact. The European woodwasp, Sirex noctilio Fabricius, is a prime example that has invaded climatically and ecologically distinct ecosystems across the Southern Hemisphere and, more recently, North America. 2. Northeastern North America presents a unique set of conditions, including pine host species, native parasitoids, a diverse assemblage of native co‐colonising insects, and fungal associates of these co‐colonisers. In North America, S. noctilio attacks both a naturalised ancestral host (Pinus sylvestris L.) from Europe and a naïve native host (P. resinosa). A large assemblage of insects and their associated bluestaining ophiostomatoid fungi colonise these pines. Competition between S. noctilio and this group is a hypothesised mechanism of biotic resistance in the invaded region of North America, possibly via superior resource capture abilities or alteration of host tissue by bluestain fungi. 3. Investigating these ecological interactions is challenging because they manifest deep in the xylem tissue. To overcome this, 30 experimentally stressed trees were systematically dissected with an electric log splitter to investigate the effects of bluestain fungi and tree factors on S. noctilio development and parasitism by native hymenopterans. 4. Body size and colonisation density were affected by pine species, with S. noctilio being 25% larger and densities three‐fold greater in P. sylvestris than P. resinosa. Survivorship was slightly negatively correlated with the proportional volume of bluestain infection. Interestingly, rhyssine (Rhyssa and Megarhyssa spp.) parasitism responded positively to greater S. noctilio density, but there was no density relationship with Ibalia leucospoides ensiger parasitism. Pine host species appears to play a strong role in S. noctilio development, which is important considering uninvaded regions of North America have a diversity of pine species that likely vary in their susceptibility to this woodborer.     

In vitro ectomycorrhizal specificity between the Asian red pine Pinus densiflora and Tricholoma matsutake and allied species from worldwide Pinaceae and Fagaceae forests

Tricholoma matsutake produces commercially valuable, yet uncultivable, mushrooms (matsutake) in association with pines in the Far East and Scandinavia and with both pines and oaks in the foothills of Tibet. Other matsutake mushrooms, such as Tricholoma anatolicum from the Mediterranean regions and Tricholoma magnivelare and Tricholoma sp. from the North Pacific Coast area of Canada and North America as well as Mexico, respectively, are associated with pines or oaks in their natural habitats. Tricholoma bakamatsutake and Tricholoma fulvocastaneum from Asia produce moderately valuable matsutake mushrooms and are solely associated with Fagaceae in nature. In this study, we demonstrate for the first time that matsutake mushrooms from Scandinavia, Mediterranean regions, North America, and Tibet form ectomycorrhizae with Pinus densiflora similar to the Far East T. matsutake. In general, worldwide T. matsutake and the symbionts of Pinaceae colonize the rhizospheres of P. densiflora as well as T. matsutake isolated from the host plant. However, T. fulvocastaneum and T. bakamatsutake formed a discontinuous Hartig net and no Hartig net, respectively, and colonized to a lesser extent as compared to T. matsutake. The data suggest that conifer-associated matsutake mushrooms in their native habitat will associate symbiotically with the Asian red pine.     

Population structure and diversity of an invasive pine needle pathogen reflects anthropogenic activity

Dothistroma septosporum is a haploid fungal pathogen that causes a serious needle blight disease of pines, particularly as an invasive alien species on Pinus radiata in the Southern Hemisphere. During the course of the last two decades, the pathogen has also incited unexpected epidemics on native and non‐native pine hosts in the Northern Hemisphere. Although the biology and ecology of the pathogen has been well documented, there is a distinct lack of knowledge regarding its movement or genetic diversity in many of the countries where it is found. In this study we determined the global population diversity and structure of 458 isolates of D. septosporum from 14 countries on six continents using microsatellite markers. Populations of the pathogen in the Northern Hemisphere, where pines are native, displayed high genetic diversities and included both mating types. Most of the populations from Europe showed evidence for random mating, little population differentiation and gene flow between countries. Populations in North America (USA) and Asia (Bhutan) were genetically distinct but migration between these continents and Europe was evident. In the Southern Hemisphere, the population structure and diversity of D. septosporum reflected the anthropogenic history of the introduction and establishment of plantation forestry, particularly with Pinus radiata. Three introductory lineages in the Southern Hemisphere were observed. Countries in Africa, that have had the longest history of pine introductions, displayed the greatest diversity in the pathogen population, indicating multiple introductions. More recent introductions have occurred separately in South America and Australasia where the pathogen population is currently reproducing clonally due to the presence of only one mating type.     

Interspecific phylogenetic analysis enhances intraspecific phylogeographical inference: a case study in Pinus lambertiana

Pinus lambertiana (sugar pine) is an economically and ecologically important conifer with a 1600-km latitudinal range extending from Oregon, USA, to northern Baja California, Mexico. Like all North American white pines (subsect. Strobus), sugar pine is highly susceptible to white pine blister rust, a disease caused by the fungus Cronartium ribicola. We conducted a chloroplast DNA (cpDNA) survey of Pinus subsect. Strobus with comprehensive geographical sampling of P. lambertiana. Sequence analysis of 12 sugar pine individuals revealed strong geographical differentiation for two chloroplast haplotypes. A diagnostic restriction site survey of an additional 72 individuals demarcated a narrow 150-km contact zone in northeastern California. In the contact zone, maternal (megagametophtye) and paternal (embryo) haplotypes were identified in 31 single seeds, demonstrating bidirectional pollen flow extending beyond the range of maternal haplotypes. The frequencies of the Cr1 allele for white pine blister rust major gene resistance, previously determined for 41 seed zones, differ significantly among seed zones that are fixed for the alternate haplotypes, or contain a mixture of both haplotypes. Interspecific phylogenetic analysis reveals that the northern sugar pine haplotype belongs to a clade that includes Pinus albicaulis (whitebark pine) and all of the East Asian white pines. Furthermore, there is little cpDNA divergence between northern sugar pine and whitebark pine (dS = 0.00058). These results are consistent with a Pleistocene migration of whitebark pine into North America and subsequent chloroplast introgression from whitebark pine to sugar pine. This study demonstrates the importance of placing phylogeographical results in a broader phylogenetic context.     

Comparative mapping in Pinus: sugar pine (Pinus lambertiana Dougl.) and loblolly pine (Pinus taeda L.)

The majority of genomic research in conifers has been conducted in the Pinus subgenus Pinus mostly due to the high economic importance of the species within this taxon. Genetic maps have been constructed for several of these pines and comparative mapping analyses have consistently revealed notable synteny. In contrast, little genomic research has been conducted on the Pinus subgenus Strobus, even though these pines have strong ecological relevance. We report a consensus genetic linkage map for sugar pine (Pinus lambertiana Dougl.) constructed with 399 single nucleotide polymorphisms markers derived from annotated genes. The map is 1,231 cM in length and organized into 19 linkage groups. Two of the mapping populations were derived from trees that were segregating for the major gene of resistance (Cr1) to Cronartium ribicola, the fungal pathogen responsible for white pine blister rust. The third mapping population was derived from a full-sib cross segregating for partial resistance to white pine blister rust. In addition, we report the first comparative mapping study between subgenera Strobus and Pinus. Sixty mapped markers were found in common between sugar pine and the loblolly pine reference map with 56 of them (93%) showing collinearity. All 19 linkage groups of the sugar pine consensus map coaligned to the 12 linkage groups of the loblolly pine reference map. The syntenic relationship observed between these two clades of pines provides a foundation for advancing genomic research and genetic resources in subgenus Strobus.     

Cronartium orientale, sp. nov., segregation of the pine gall rust in eastern Asia fromCronartium quercuum

The Asian pine gall rust, which has hitherto been assigned toCronartium quercuum distributed in North America, is described asC. orientale, sp. nov. The spermogonial and aecial states occur on hard pines, and the uredinial and telial states occur on various oaks.Cronartium orientale has globose, almost hyaline basidiospores in contrast to the ellipsoid, yellow-orange ones of North AmericanC. quercuum s.l. Characteristics of the new rust species in morphology, DNA analysis, and host alternation are discussed.     

SEASONAL TRENDS IN RATES OF PHOTOSYNTHESIS AND RESPIRATION OF LOBLOLLY PINE AND WHITE PINE SEEDLINGS

Mc Gregor , William H. Davis (Clemson Coll., Clemson, S.C.), and Paul J. Kramer . Seasonal trends in rates of photosynthesis and respiration of loblolly pine and white pine seedlings. Amer. Jour. Bot. 50(8): 760–765. Illus. 1963.—Seasonal trends in the rates of photosynthesis and respiration of potted loblolly and white pine seedlings were studied by measuring CO₂ exchange with an infra-red gas analyzer at intervals during a year. The seedlings were kept out-of-doors, but measurements were made indoors at 25 C and 4000 ft-c of light. Beginning in February, the rate of photosynthesis per plant of both species increased, reaching a peak in mid-September for loblolly pine and in mid-July for white pine and then declining rapidly after mid-September for both species. The spring increase began before new needles emerged and the autumn decline was not accompanied by appreciable loss of foliage. The respiration rate of loblolly pine increased steadily throughout the year. Respiration of white pine increased until mid-May and then remained fairly constant through the remainder of the year. Maximum rate of photosynthesis per unit of fascicle length occurred in July for the white pine and in May for the loblolly pine, and rates declined after September in both species. Respiration rate per unit of fascicle length showed a marked increase as spring growth began in April, then decreased to a minimum in September and increased during the winter in both species. Total chlorophyll per seedling reached a maximum in September for both species and declined slightly during winter. Total chlorophyll per unit of fascicle length increased in the spring, declined slightly in midseason, and increased again in September. Photosynthesis per unit of chlorophyll reached a maximum in May for loblolly pine and in July for white pine. Stem elongation of white pine was 88% completed by May 15. On the same date, stem elongation of loblolly pine was only 42% completed.     

Walking Response of the Mediterranean Pine Engraver, <Emphasis Type="Italic">Orthotomicus erosus</Emphasis>, to Novel Plant Odors in a Laboratory Olfactometer

When an herbivorous insect enters a new geographic area, it will select host plants based on short and long distance cues. A conifer-feeding bark beetle that has been recently introduced to North America, the Mediterranean pine engraver, Orthotomicus erosus (Wollaston), has a potentially wide host range, especially among members of the Pinaceae. The long-distance response of the beetles to tree odors may be a key feature of the mechanism of host recognition and selection. We used a laboratory olfactometer to study the walking response of 1,440 O. erosus to odor cues from the bark and phloem of six North American tree species. The beetle moved toward the angiosperm non-host Betula papyrifera more than would be expected by chance, but had a neutral response to odors of two tree species that support reproduction and three species that do not. These results suggest that tree odors alone may not be adequate for O. erosus to recognize novel hosts.     

Cones structure and seed traits of four species of large‐seeded pines: Adaptation to animal‐mediated dispersal

Seed dispersal selection pressures may cause morphological differences in cone structure and seed traits of large‐seeded pine trees. We investigated the cone, seed, and scale traits of four species of animal‐dispersed pine trees to explore the adaptations of morphological structures to different dispersers. The four focal pines analyzed in this study were Chinese white pine (Pinus armandi), Korean pine (P. koraiensis), Siberian dwarf pine (P. pumila), and Dabieshan white pine (P. dabeshanensis). There are significant differences in the traits of the cones and seeds of these four animal‐dispersed pines. The scales of Korean pine and Siberian dwarf pine are somewhat opened after cone maturity, the seeds are closely combined with scales, and the seed coat and scales are thick. The cones of Chinese white pine and Dabieshan white pine are open after ripening, the seeds fall easily from the cones, and the seed coat and seed scales are relatively thin. The results showed that the cone structure of Chinese white pine is similar to that of Dabieshan white pine, whereas Korean pine and Siberian dwarf pine are significantly different from the other two pines and vary significantly from each other. This suggests that species with similar seed dispersal strategies exhibit similar morphological adaptions. Accordingly, we predicted three possible seed dispersal paradigms for animal‐dispersed pines: the first, as represented by Chinese white pine and Dabieshan white pine, relies upon small forest rodents for seed dispersal; the second, represented by Korean pine, relies primarily on birds and squirrels to disperse the seeds; and the third, represented by Siberian dwarf pine, relies primarily on birds for seed dispersal. Our study highlights the significance of animal seed dispersal in shaping cone morphology, and our predictions provide a theoretical framework for research investigating the coevolution of large‐seeded pines and their seed dispersers.     

High intercontinental migration rates and population admixture in the sapstain fungus Ophiostoma ips

Ophiostoma ips is a common fungal associate of various conifer-infesting bark beetles in their native ranges and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we used 10 microsatellite markers to investigate the population biology of O. ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin as well as patterns of spread of the fungus and its insect vectors. The markers resolved a total of 41 alleles and 75 haplotypes. Higher genetic diversity was found in the native populations than in the introduced populations. Based on the origin of the insect vectors, the populations of O. ips in Australia would be expected to reflect a North American origin, and those in Chile and South Africa to reflect a European origin. However, most alleles observed in the native European population were also found in the native North American population; only the allele frequencies among the populations varied. This admixture made it impossible to confirm the origin of the introduced Southern Hemisphere (SH) populations of O. ips. There was also no evidence for specificity of the fungus to particular bark beetle vectors or hosts. Although O. ips is thought to be mainly self-fertilizing, evidence for recombination was found in the four native populations surveyed. The higher genetic diversity in the North American than in the European population suggests that North America could be the possible source region of O. ips.     

Mountain Pine Beetles Use Volatile Cues to Locate Host Limber Pine and Avoid Non-Host Great Basin Bristlecone Pine

The tree-killing mountain pine beetle (Dendroctonus ponderosae Hopkins) is an important disturbance agent of western North American forests and recent outbreaks have affected tens of millions of hectares of trees. Most western North American pines (Pinus spp.) are hosts and are successfully attacked by mountain pine beetles whereas a handful of pine species are not suitable hosts and are rarely attacked. How pioneering females locate host trees is not well understood, with prevailing theory involving random landings and/or visual cues. Here we show that female mountain pine beetles orient toward volatile organic compounds (VOCs) from host limber pine (Pinus flexilis James) and away from VOCs of non-host Great Basin bristlecone pine (Pinus longaeva Bailey) in a Y-tube olfactometer. When presented with VOCs of both trees, females overwhelmingly choose limber pine over Great Basin bristlecone pine. Analysis of VOCs collected from co-occurring limber and Great Basin bristlecone pine trees revealed only a few quantitative differences. Noticeable differences included the monoterpenes 3-carene and D-limonene which were produced in greater amounts by host limber pine. We found no evidence that 3-carene is important for beetles when selecting trees, it was not attractive alone and its addition to Great Basin bristlecone pine VOCs did not alter female selection. However, addition of D-limonene to Great Basin bristlecone pine VOCs disrupted the ability of beetles to distinguish between tree species. When presented alone, D-limonene did not affect behavior, suggesting that the response is mediated by multiple compounds. A better understanding of host selection by mountain pine beetles could improve strategies for managing this important forest insect. Moreover, elucidating how Great Basin bristlecone pine escapes attack by mountain pine beetles could provide insight into mechanisms underlying the incredible longevity of this tree species.     

Breeding performance and longevity of Tomicus destruens on Mediterranean and continental pine species

The pine shoot beetle Tomicus destruens (Wollaston) (Coleoptera: Curculionidae: Scolytinae) is one of the main pests of Mediterranean forests, where it is oligophagous on Mediterranean pines. However, possible global warming may make the insect move to higher latitudes and altitudes, allowing it to attack new pine species. In this respect, the aim of the present article was to assess both the acceptance and performance of T. destruens offered host and non‐host pine species. A no‐choice breeding experiment was set up under laboratory conditions, using logs of three Mediterranean (Pinus pinea L., Pinus pinaster Miller, and Pinus halepensis Aiton) and two continental (Pinus nigra Arnold and Pinus sylvestris L.) pine species. Log debarking at the end of adult emergence assessed parent fecundity, egg, and larval mortality. The quality of callow adults emerging from each tested pine was evaluated on the basis of their longevity on a semiartificial diet. Tomicus destruens colonised all tested pine species, but did not reproduce in Scots pine, taking about 79 days to complete development with no differences among pines tested. The best breeding performance, evaluated as female fecundity and adult production, was observed in P. halepensis, and the lowest in P. pinaster. On average, adults emerging from P. pinea survived longer (83 days) than from other pines, and adult longevity was the lowest in males emerging from P. nigra. Austrian pine, which under natural conditions is usually not a host of T. destruens, allowed insect development and adult production similar to P. pinea and P. pinaster.