纵坑切梢小蠹对云南松蛀害研究

在昆明地区,纵坑切梢小蠹Tomicus piniperda L.表现出枝梢聚集、树干蛀害等重要的行为学特征,形成三种基本蛀害模式。横坑切梢小蠹、蓝色伴生真菌参与了纵坑切梢小蠹危害过程,并在其中发挥积极作用。上述因素的综合影响,加强了纵坑切梢小蠹对云南松Pinus yunnanensis寄主树木的危害能力。     

Attack dynamics of the pine shoot beetle, Tomicus piniperda (Col.; Scolytinae) in Scots pine stands defoliated by Bupalus piniaria (Lep.; Geometridae)

Abstract 1 After a 1‐year, extensive pine looper (Bupalus piniaria) outbreak, plots were laid out to study tree susceptibility to attack, and performance of Tomicus piniperda in pine trees suffering from varying levels of defoliation. 2 Tomicus piniperda was the dominating stem‐attacking species among the primary stem colonizers, and 82% of all trees that died had been colonized by T. piniperda. 3 Beetle attacks primarily struck severely defoliated trees, i.e. trees that suffered from 90% to 100% defoliation. 4 Beetle attacks peaked in the second year after cessation of the outbreak, and suppressed trees were both more frequently attacked and more susceptible to beetle attack than intermediate and dominant trees. 5 Trees surviving beetle attacks carried more foliage than trees that did not survive the attacks. 6 A single year of severe defoliation is enough to render pine trees susceptible to secondary pests, such as T. piniperda.     

云南横坑切梢小蠹生物学研究

横坑切梢小蠹Tomicus minor (Hartig)是云南松Pinus yunnanensis Franchet的主要次期性害虫之一。1980年以来,该虫与纵坑切梢小蠹T. piniperda（L.）一起在中国西南部大量发生,导致数十万公顷云南松林受害。本文报道了横坑切梢小蠹在云南地区的生活史、生长、发育、繁殖等生物学特征。横坑切梢小蠹年生活史为一代,前后两代在冬春季有部分重叠。成虫羽化于4月下旬开始陆续,5 月下旬结束。成虫羽化后即飞到树冠上蛀食枝梢,直到11月发育成熟,开始繁殖。在此期间,每头成虫可以蛀食4～6个枝梢。横坑切梢小蠹在云南没有越冬习性。繁殖期从11月至次年3月。成虫主要在已经受到纵坑切梢小蠹危害的树木的中、下部产卵。繁殖期较纵坑切梢小蠹约迟1周。由于横坑切梢小蠹从枝梢到树干对云南松持续危害,对树木的危害性较在其它地区更为严重。横坑切梢小蠹利用受到纵坑切梢小蠹蛀害的树木繁殖产卵,加强了蠹虫对云南松树的危害,加速了受害树木的死亡进程。横坑切梢小蠹的上述生物生态学特征是该虫对云南松造成严重危害的重要原因。从横坑切梢小蠹虫体和虫坑中检测到伴生真菌云南半帚孢Leptographium yunnanensis。横坑切梢小蠹对该菌的带菌率在蛀梢期为11.5%;在蛀干中期约为10%～26%。     

Impacts of Tomicus minor on distribution and reproduction of Tomicus piniperda (Col., Scolytidae) on the trunk of the living Pinus yunnanensis trees

This study investigated the impacts of Tomicus minor on Tomicus piniperda when the two Tomicus species coexist in the trunks of living Yunnan pine (Pinus yunnanensis L.) trees growing in the Kunming region, in south-western China. Tomicus piniperda mostly locates in the mid- and upper trunks of Yunnan pine tree; whereas T. minor mainly attacks the mid- and lower trunks. In the mid-trunk area from 1.0 to 5.0 m above ground, there are overlapping attack zones for the two Tomicus species, which accounts for an average of 80% of the entire zone occupied by T. piniperda and an average of 70% of the zone occupied by T. minor. In correspondence with their attack distributions, the average attack densities of the two species varied with height along the trunk, with 165.3 egg galleries per m² at a height of 6 m for T. piniperda, and 138.2 egg galleries per m² at the 1 m height for T. minor. It is suggested that T. minor adjusts its attack pattern with respect to T. piniperda, and thereby minimizes interspecific competition. No remarkable difference of average T. piniperda egg gallery length was found between the zone in which only T. piniperda occurred and the zone in which T. piniperda and T. minor coexisted; this is suggested to be due to low host quality in the upper trunk region where only T. piniperda was present. The number of T. piniperda larval galleries was highest when only T. piniperda was present, and decreased as T. piniperda and T. minor coexisted, particularly in the case when the density of T. piniperda was less than that of T. minor. Average larval density was 1649 larval galleries per m² where only T. piniperda occurred. However, when T. piniperda coexisted with T. minor, T. piniperda larval density averaged 1010 per m² when T. piniperda density was higher than T. minor, and averaged 442 per m² when T. piniperda density was less than T. minor, which led to the conclusion that T. minor makes a negative impact on T. piniperda reproduction when the two Tomicus species jointly colonize the same trunk of Yunnan pine tree.     

Attraction of the bark beetle Tomicus piniperda to Scots pine trees in relation to tree vigor and attack density

The attraction of Tomicus piniperda (L.) (Coleoptera: Scolytidae) to Scots pine trees of low and higher vigor with and without previous attacks was monitored with sticky traps. Somewhat higher numbers of beetles were caught on low vigor trees than on trees of higher vigor, indicating differences in olfactory stimuly between the two classes of trees.Many more beetles were caught on trees attacked by T. piniperda and on trees with simulated bark beetle galleries (manually drilled holes) than on control trees with no or only a few attacks. The strong attraction of beetles to attacked trees is attributed to the beetles responding to host volatiles released from the galleries.

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Zusammenfassung Der Anflug von Tomicus piniperda (L.) (Coleoptera: Scolytidae) an Kiefern in schlechtem oder besserem Gesundheitszustand, mit oder ohne vorherigen Befall, wurde mit Hilfe von Leimfallen untersucht. An Bäumen in schlechtem Zustand wurden etwas mehr Käfer gefangen als an Bäumen in besserem Gesundheitszustand. Das deutet auf Unterschiede in Geruchsreizen zwischen den beiden Klassen des Baumzustands hin.An Kiefern, die von T. piniperda befallen waren oder simulierte Einbohrungen (von Hand gebohrte Löcher) hatten, wurden viel mehr Käfer gefangen als an Kontrollbäumen ohne oder mit sehr geringem Befall. Der starke Anflug von Käfern an befallene Bäume wird gedeutet als Reaktion auf Duftstoffe des Wirts, die aus den Borkenkäfergängen abgegeben werden.

     

Colonization of disturbed Scots pine trees by bark‐ and wood‐boring beetles

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Distribution and population genetic structure of the Mediterranean pine shoot beetle Tomicus destruens in the Iberian Peninsula and Southern France

1 The Mediterranean pine shoot beetle Tomicus destruens has long been indistinguishable from its congeneric Tomicus piniperda. Both species attack pines, and can be found in sympatry. The geographical distribution of T. destruens is still unclear in most of the Mediterranean Basin. 2 We aimed to describe the geographical distribution and zones of sympatry of both species in the Iberian Peninsula and France, and to study the molecular phylogeographical pattern of T. destruens. 3 Tomicus spp. adults were sampled in Portugal, Spain and France, and a portion of the mitochondrial genes COI and COII was sequenced for 84 individuals. Sequences were aligned to a data set previously obtained from French localities. 4 Tomicus destruens was found in all populations, except for one locality in Portugal and in the Landes (France). It was in sympatry with T. piniperda in two locations on Pinus pinaster and one location on Pinus radiata. 5 Within‐population genetic diversity was high, but we found a significant pattern of spatial distribution of genetic variation, as well as a significant effect of the host tree. 6 The data suggest the existence of two glacial refugia, from which T. destruens recolonized its current range. One refugium was located in Portugal where the beetle probably evolved on P. pinaster. The corresponding haplotypes show a West–East frequency gradient. The other refugium was probably in the eastern range, where the beetles evolved on Pinus halepensis and P. pinea. The corresponding haplotypes show an East–West frequency gradient.     

Shoot damage by Tomicus sp. (Coleoptera: Scolytidae) and effect on Pinus yunnanensis resistance to subsequent reproductive attacks in the stem

Abstract 1 In South‐western China, Yunnan pines Pinus yunnanensis, suffer considerable damage from an undescribed Tomicus sp. previously thought to be T. piniperda. 2 To assess the effect of shoot maturation feeding (during which an aggregation process appears to occur) on host resistance to attacks on the bole, the relationships between shoot damage, bole attack density and tree survival were studied. 3 Attack distribution in the crown and in the stem did not vary between killed and surviving trees, indicating that mortality is determined by the quantity of attacks. 4 The level of shoot damage and bole attack density were positively and linearly correlated. This can be explained by the fact that bole attacks are caused by beetles coming from the crown of the same tree. 5 A critical threshold of bole attack density (around 80 attacks/m²) above which trees die was observed. However, because attacks continue after this threshold is reached, the density of failed attacks on the killed trees was used as an estimator of the threshold density. It decreased when shoot damage increased. 6 The existence of a critical threshold of shoot damage (60% damaged shoots) was also demonstrated. Above this threshold, stem attack density was always sufficiently high to kill trees. 7 The results emphasize that concentration of shoot attacks is the main reason for the extensive tree damage observed in China. 8 A model of relationships between shoot and stem attacks is proposed, suggesting that management to reduce shoot attacks would protect trees from dying by both decreasing the number of bole attacks and raising the threshold for successful attack density on the bole to levels that could not be attained.     

Development of an improved attractive lure for the pine shoot beetle, Tomicus piniperda (Coleoptera: Scolytidae)

Abstract 1 The pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), is an exotic pest of pine, Pinus spp., and was first discovered in North America in 1992. 2 Although primary attraction to host volatiles has been clearly demonstrated for T. piniperda, the existence and role of secondary attraction to insect‐produced pheromones have been widely debated. 3 Currently, commercial lures for T. piniperda include only the host volatiles α‐pinene in North America and α‐pinene, terpinolene and (+)‐3‐carene in Europe. Several potential pheromone candidates have been identified for T. piniperda. 4 We tested various combinations of host volatiles and pheromone candidates in Michigan, U.S.A., and Ontario, Canada, to determine an optimal blend. 5 Attraction of T. piniperda was significantly increased when trans‐verbenol (95% pure, 3.2%cis‐verbenol content) was added with or without myrtenol to α‐pinene or to blends of α‐pinene and other kairomones and pheromone candidates. 6 Our results, together with other research demonstrating that trans‐verbenol is produced by T. piniperda, support the designation of trans‐verbenol as a pheromone for T. piniperda. A simple operational lure consisting of α‐pinene and trans‐verbenol is recommended for optimal attraction of T. piniperda.     

Effects of green tree retention and prescribed burning on the crown damage caused by the pine shoot beetles (Tomicus spp.) in pine-dominated timber harvest areas

Abstract: We explored how two recently introduced methods to promote biodiversity during the timber harvest in boreal forests – green tree retention and use of fire – may affect damages caused by pine shoot beetles (Tomicus piniperda and Tomicus minor; Col., Scolytinae) in the surrounding pine forests. The experimental design included 24 separate study sites, 3–5 ha each, which were assigned to different treatments according to factorial design. Retention levels included 0, 10, 50 m³/ha and uncut controls. Twelve of the sites were burned and thus there were three replicates of each treatment combination. Old and new fallen pine shoots were counted from transects in adjacent pine‐dominated forests 2 and 3 years after the treatments. Populations of Tomicus spp. in the sites were monitored using window traps before and after the treatments, and by examining felled sample trees. Numbers of fallen shoots returned to background levels around unburned and burned clearcuts with no retention trees in 3 years after the treatments, but remained still at increased level in burned harvested sites with 10 and 50 m³ of retained trees per hectare. Numbers of fallen shoots in burned uncut forests increased in one site only, where the fire was intense enough to kill large pine trees, but the damage did not extend outside the burned area. Shoot numbers remained at such low levels (<18 000 shoots/ha) in all treatment combinations that growth losses were not likely. Numbers of egg galleries of Tomicus spp. in trees killed by fire were low, indicating that burnings that take place after the swarming of Tomicus beetles create dead wood that is not optimal for the breeding of these pests. We conclude that green tree retention and prescribed use of fire do not automatically affect populations of Tomicus spp. more than traditional forestry operations (thinnings and clearcuttings) do.     

纵坑切梢小蠹对云南松蛀害研究

在昆明地区,纵坑切梢小蠹Tomicus piniperda L.表现出枝梢聚集、树干蛀害等重要的行为学特征,形成三种基本蛀害模式。横坑切梢小蠹、蓝色伴生真菌参与了纵坑切梢小蠹危害过程,并在其中发挥积极作用。上述因素的综合影响,加强了纵坑切梢小蠹对云南松Pinus yunnanensis寄主树木的危害能力。     

Niche‐based relationship between sympatric bark living insect pests and tree vigor decline of Pinus yunnanensis

Forest stands of Pinus yunnanensis Franch in southwestern China are seriously damaged by several bark living insect pests. These pests commonly exist in the same host tree and exploit limited phloem resources. In this study, we hypothesized that sympatric pests would occupy different ecological niches to reduce interspecific competition, and their coordinated attack would aggravate the tree vigor decline of P. yunnanensis. To quantify the ecological niches, we used a sampling method involving three dimensional divisions of tree resource states: (a) sample plot dimension (to evaluate the extent of pest colonization at plot scale), (b) trunk height dimension, and (c) tree vigor dimension. Those attacked pine canopies and colonized trunks were analysed in the field study. The results showed that Tomicus minor and Tomicus yunnanensis both widely and uniformly distributed in lightly, moderately and heavily damaged canopies while they aggregated on particular trunks of dying and withered trees. Lower and middle trunk sections (1–4 m) were mainly occupied by Monochamus alternatus and T. minor, yet T. yunnanensis dominated the upper parts (5–6 m). There was an overlap of the pine shoot beetles in the middle sections (2–4 m), whereas all three species were ecologically segregated in other trunk sections. During the shoot feeding phase, tree vigor declined with pine shoot beetles' increasing shoot feeding density. They coexisted in the same host tree, while M. alternatus only attacked dying and withered tree trunks, causing a greater infestation. Colonization of pine shoot beetle then followed by M. alternatus could be the major causes of tree mortality. This study highlights the resource utilization pattern of sympatric bark living insect pests corresponding with tree vitality. Those findings would help to understand the mechanisms of pest outbreak in P. yunnanensis ecosystem and provide potential guidance for developing an early monitoring pest warning system.     

Host resistance in defoliated pine: effects of single and mass inoculations using bark beetle-associated blue-stain fungi

1 In 1996, 7000 ha of pine forests were defoliated by the pine looper Bupalus piniaria in south‐western Sweden. 2 The susceptibility of trees of different defoliation classes (0, 30, 60, 90 and 100% defoliation) to beetle‐vectored blue‐stain fungi was tested in inoculation experiments. Forty and 120‐year‐old Scots pine trees were inoculated with ‘single’, i.e. a few inoculations of Leptographium wingfieldii and Ophiostoma minus, two blue‐stain fungi associated with the pine shoot beetle Tomicus piniperda. The young trees were also ‘mass’ inoculated with L. wingfieldii at a density of 400 inoculation points per m² over a 60 cm stem belt. 3 Host tree symptoms indicated that only trees with 90–100% defoliation were susceptible to the mass inoculation. 4 Single inoculations did not result in any consistent differences in fungal performance between trees of different defoliation classes, regardless of inoculated species or tree age class. 5 Leptographium wingfieldii produced larger reaction zones than O. minus, and both species produced larger lesions in old than in young trees. 6 As beetle‐induced tree mortality in the study area occurred only in totally defoliated stands, mass inoculations seem to mimic beetle‐attacks fairly well, and thus seem to be a useful tool for assessing host resistance. 7 As even severely defoliated pine trees were quite resistant, host defence reactions in Scots pine seem to be less dependent on carbon allocation than predicted by carbon‐based defence hypotheses.     

Evolving Management Strategies for a Recently Discovered Exotic Forest Pest: The Pine Shoot Beetle, Tomicus Piniperda (Coleoptera)

Established populations of the Eurasian pine shoot beetle (Tomicus piniperda (L.); Coleoptera: Scolytidae) were first discovered in North America in Ohio in 1992. As of 31 December 2000, T. piniperda was found in 303 counties in 12 US states (Illinois, Indiana, Maine, Maryland, Michigan, New Hampshire, New York, Ohio, Pennsylvania, Vermont, West Virginia, and Wisconsin) and in 43 counties in 2 Canadian provinces (Ontario and Quebec). A federal quarantine imposed in November 1992 regulates movement of pine (Pinus) trees, logs, and certain pine products from infested to uninfested areas within US. The forest products, Christmas tree, and nursery industries are affected by the quarantine. This paper summarizes information on the discovery and spread of T. piniperda in North America, survey efforts, recent interception history, development and changes in the federal quarantine, development of a national compliance management program, and extension and research efforts.     

纵坑切梢小蠹蛀梢期空间分布

在昆明地区,纵坑切梢小蠹(Tomicus piniperda)成虫蛀梢多集中在蛀干木附近。 种群密度以蛀干木为中心向周围呈指数递减,散布半径约30m。在蛀梢过程中,该种群逐渐向新区扩张。在树冠内,纵坑切梢小蠹主要分布在4-10轮枝上。第7轮枝虫口百分率最高。6-7轮枝受害率最大。 树冠上层受害较其下层严重。从树冠水平层次考察,树冠外层虫量相对集中,约为树冠中、内层虫量之和。 树冠内层虫量最少。纵坑切梢小蠹在树冠内的种群分布系由梢径、种群密度、蛀梢行为、降落方式、光照等因素综合影响的结果。     

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.     

Induced defence reaction in Scots pine following stem attacks by Tomicus piniperda

The induced defence reaction of Scots pine Pinus sylvestris to stem attacks by the common pine shoot beetle, Tomicus piniperda (Col, Scolytidae), was studied by inducing natural attacks on young Scots pine trees of different vigour Pruned trees were more heavily attacked by T piniperda than unpruned ones Vigorous trees successfully contained the attacking beetles within resinous lesions, whereas less vigorous trees failed to defend themselves The content of resin acids increased dramatically in the lesions on all trees, and the resin acid composition differed somewhat between some treatments Starch accumulation in the inner bark of the main stem was lower in pruned trees than in unpruned ones, and starch reserves were depleted in the most heavily attacked trees All but one of the unpruned trees survived the attack, whereas most of the severely pruned ones died following attack by beetles at densities exceeding c 300 egg galleries m⁻²     

Morphological and genetic identification of the three pine pests of the genus Tomicus (Coleoptera, Scolytidae) in Europe

Abstract

• 1 Morphological characters were elaborated and part of the mitochondrial COI gene was sequenced in order to facilitate the determination of the three European pine bark beetles Tomicus piniperda, T. destruens and T. minor. The sequence information also provided the first information on the phylogenetic and phylogeographical relationships of these species.
• 2 Three hair rows were found on the antennal club of T. destruens between the second and third suture. Tomicus piniperda had only one row. Three different hair types were detected on the elytra – two hair types were found on T. piniperda, whereas the third hair type was only detected on the elytra of T. destruens.
• 3 The COI region (445 bp) revealed high sequence divergence among T. destruens, T. piniperda and T. minor. The three species proved to be monophyletic species with 16.98–19.23% sequence divergence. A phylogenetic approach placed T. minor and T. destruens as sister taxa, which contradicts the morphological findings.
• 4 European populations of T. piniperda shared two haplotypes, indicating a homogenous distribution of the genotypes. In the American populations only one of these European haplotypes was found. The Greek, Italian and Spanish T. destruens populations revealed three population‐specific haplotypes, indicating restricted gene flow.
• 5 Species‐specific primers were designed to allow a rapid and definitive determination of the two sibling Tomicus species by PCR.

     

Threats to pine stands by the pine shoot beetles Tomicus piniperda (L.) and Tomicus minor (Hart.) (Col., Scolytidae) around a sawmill in southern Poland

Forest stands growing around sawmills are especially exposed to damage due to the feeding by the pine shoot beetles Tomicus piniperda (L.) and Tomicus minor (Hart.) (Col., Scolytidae) in the pine shoots, causing a considerable loss of increment. The purpose of this study was to determine the relation of the distance zone of a stand from a sawmill to the density of the pine shoot fall, width of annual rings, and pine stand quality. The investigations were carried out between 1992 and 1996 in a Pinus silvestris – Abies alba stand adjacent to a sawmill in the Zagnańsk Forest District. In the investigated stand, eight zones situated at different distances from the sawmill were marked out, in which the fallen pine shoots were collected and dendrometric measurements taken. The study results showed that the pine shoot fall in the area up to 300 m away from the sawmill was significantly greater than the fall in zones situated further away. In addition, the mean current annual and 10-year radial increments at breast height were significantly smaller, and the pine stand quality class was lower within that area. The radial increment at breast height in the area up to 300 m away from the sawmill was almost twice as low as that in the control area, and about 40% lower than the increment in the area situated 300–900 m away. The increment pattern of pine in this area differed from that of fir, suggesting that the incremental loss and lower pine stand quality are the result of long-term feeding of the pine shoot beetles in the pine shoots. These results indicate that other causes, such as differences in site class, climatic factors or air pollution, can be excluded.     

Evidence of interaction between Sirex noctilio and other species inhabiting the bole of Pinus

• 1 Sirex noctilio is a woodwasp native to Eurasia and Northern Africa and has recently been found infesting pines in eastern North America. Its pest status in this new range is not yet known, although it is an important pest in other areas where it has been introduced. Pinus spp. in North America are hosts to several native and alien species of subcortical insects. Interactions between the woodwasp and these species may influence its distribution or the characteristics of its life history, thus affecting its population dynamics over time.
• 2 Sixty S. noctilio‐infested Pinus spp. were felled in Ontario, Canada, and all phloem‐feeding and woodboring insects were collected and identified from each 1‐m section of the tree.
• 3 Sirex noctilio was in a tree alone 10% of the time but commonly shared the tree with subcortical beetles, such as Tomicus piniperda, Pissodes nemorensis, Ips grandicollis, Gnathotrichus materiarius and Monochamus carolinensis. The woodwasp was distributed throughout the tree stem and this distribution overlapped with that of the beetles.
• 4 Fewer but larger S. noctilio males emerged from trees with beetles compared with those without, although there was no statistical difference in females.
• 5 These findings suggest that co‐habiting beetles could negatively affect S. noctilio population dynamics over time. The potential mechanisms for this interaction are discussed.