A-3型松褐天牛引诱剂诱虫谱研究

2002～2004年,在广州地区应用A-3型松褐天牛Monochamus alternatus Hope(鞘翅目Coleoptera天牛科Cerambycidae)引诱剂诱捕鞘翅目昆虫,结果表明:A-3型松褐天牛引诱剂具有较广的诱虫谱,可以诱捕到鞘翅目中10个科48种昆虫;松树的主要蛀干害虫是松褐天牛、赤梗天牛Arhopalus unicolor Ganhan、马尾松角胫象Shirahoshizo patruelis Voss、松瘤象Hyposipalus gigas Fabricius和松纵坑切梢小蠢Tomicus piniperda Linnaeus等小蠹虫;进一步分离所诱捕的松褐天牛及其他松树主要蛀干害虫携带松材线虫Bursaphelenchus xylophilus Nickle的情况,发现松褐天牛与赤梗天牛均携带松材线虫,其中松褐天牛是松材线虫病最重要的传播媒介.     

云南松树冠受害表征与有害生物复合危害的关系

【目的】云南松Pinus yunnanensis Franch是我国西南地区重要的生态林造林树种之一。钻蛀性害虫松墨天牛Monochamus alternatus Hope、几种切梢小蠹Tomicus spp.、微红梢斑螟Dioryctria rubella Hampson和一种病害松针褐斑病Lecanosticta acicola能在云南松人工林内严重发生,对森林健康构成威胁。本研究选取树冠枯梢率作为云南松树势的评价标准,筛选出引起树冠枯梢的主要因子,建立云南松树冠受害表征与不同种类(数量)有害生物复合危害之间的关系,以期探索对云南松有害生物进行遥感监测预警的精准判别方法。【方法】设置标准地,抽样选择35株受害状为局部枝梢枯萎和29株系统性萎蔫的云南松,分别调查其上有害生物的种类和数量。使用Pearson相关性分析等方法研究云南松枯梢率与各致害因子(松墨天牛、切梢小蠹、微红梢斑螟和松针褐斑病)之间的关系。通过多元线性逐步回归的方法,筛选出导致云南松树冠局部枯梢的主要因子,建立枯梢率关于主要有害生物种群数量的反演模型。【结果】局部枝梢枯萎植株的树冠枯梢率与两种切梢小蠹的种群数量均呈高度正相关,与树木胸径和其他致害因子呈较弱或无相关性。分析标准地每木调查结果发现,树冠有无病梢不能显著影响枯梢率情况。建立了通过枯梢率(Y)反演云南松树冠两种切梢小蠹混合种群数量(X)的回归模型:Y=12.0984+0.9835 X,Adj-R2=0.8081。明确了在蛀梢阶段,云南松树势随着切梢小蠹种群数量上升而下降。在蛀干阶段,切梢小蠹和松墨天牛的钻蛀活动主要集中在濒死木和枯立木上。【结论】引起树冠局部枯梢、树势下降的主要因子为横坑切梢小蠹和云南切梢小蠹成虫的蛀梢活动;引起树冠系统性萎蔫、树木死亡的主要原因是松墨天牛与切梢小蠹的蛀干活动。应用本研究模型可通过判别云南松树冠枯梢率估算两种切梢小蠹在蛀梢期的混合种群数量,为航天遥感或无人机监测虫情提供可靠的理论基础。     

利用引诱剂监测林木主要蛀干害虫

于2004~2006年间对浙江省乐清市林木蛀干害虫种类进行调查,结果显示该辖区共有47种蛀干害虫,隶属于8科41属。重点对松墨天牛Monochamus alternatus Hope、削尾材小蠹Xyleborus mutilatus Blandford等的成虫活动期林间种群数量动态进行监测。结果表明,松墨天牛林间活动期为4月下旬至11月中旬,6月上旬为高峰期,其诱获的成虫数占监测总数的41.1%,初步显示该虫在浙南地区松林内的种群数量变化规律。同时,还初步了解到削尾材小蠹成虫的活动规律。     

太阳能光源和引诱剂对松墨天牛的组合诱捕效果

[目的]为明确不同太阳能光源波长对松墨天牛Monochamus alternatus诱捕效果的影响,并评价太阳能光源与引诱剂联合应用对松墨天牛引诱剂的促进作用,以应用于松墨天牛的绿色防控.[方法]选择波长为365-370、370-375、380-385、390-395、395-400、400-405、405-420、515-520、580-590和600-610nm的10种太阳能LED光源,测定不同光源对松墨天牛的林间诱捕效果,并筛选出诱捕效果最好的光源波长,选择此波长与引诱剂组合对松墨天牛进行诱捕试验.[结果]10种不同波长太阳能光源对松墨天牛均表现出一定的引诱作用,其中波长为380-385 nm的太阳能光源对松墨天牛诱捕效果最好,诱捕量为(12.00±6.53)头,其次是390-395nm,显著优于波长为365-370、370-375、390-395、395-400、400-405、405-420、515-520、580-590和600-610 nm;与单独使用引诱剂相比,太阳能光源与引诱剂组合对松墨天牛诱捕效果具有显著的促进作用(P＜0.05).太阳能光源与引诱剂诱捕量均值为(21.83±10.65)头,比单独引诱剂诱捕效果提高35％,为单独太阳能光源诱捕效果的5.9倍;引诱剂诱、太阳能光源和太阳能光源与引诱剂联合应用捕到的松墨天牛雌雄性比分别为2.4∶1、1.7∶1和3.3∶1,均具有显著的偏雌性.[结论]太阳能光源与引诱剂联合应用具有比单独引诱剂诱捕更好的诱捕效果.这一结论对降低松墨天牛种群密度和减少松材线虫病传播几率具有重要意义.     

云南切梢小蠹对云南松树的蛀干危害及致死机理

蛀干危害是云南切梢小蠹致死云南松树的关键环节。通过控制云南切梢小蠹蛀干密度,对云南切梢小蠹在自然条件下蛀干行为与危害进行了首次探讨。结果表明,云南切梢小蠹蛀干密度与云南松存活率呈负相关,蛀干密度直接决定云南松死亡或存活。研究发现,蛀干密度115坑/m2是云南松树的最低致死密度阈值,云南松树在蛀干密度低于26.4坑/m2情况下存活,在26.4-115坑/m2有部分存活,超过115坑/m2以后将被害致死。云南切梢小蠹对树干攻击形成有卵和无卵两类坑道。形成无卵坑道的蛀干攻击可导致树势衰弱,形成有卵坑道的蛀干危害严重破坏了韧皮组织,是导致云南松死亡的直接原因。     

松树皮下节肢动物种群动态研究初报

报道用环剥和砍伐模拟松树树势减弱和失水干枯的受害情况,同时观察松树皮下害虫侵入动态。环剥和砍伐对马尾松树皮下昆虫的入侵有完全不同的影响。松树失水,渐趋干枯是蛀干害虫得以入侵的主要原因。马尾松树皮下有多种蛀干害虫先后侵入、同时发生,其中松墨天牛为先锋虫种,依入侵先后顺序为松墨天牛、纵坑切梢小蠹、马尾松角胫象、小松角胫象、家白蚁。有多种捕食性和寄生性天敌跟随进入树干,虫种包括长线阎甲、根露尾甲、管氏肿腿蜂、黄隐翅虫、花绒穴甲、茧蜂、囊螨。     

APF-Ⅰ型松墨天牛引诱剂的应用技术研究

为完善APF-Ⅰ型松墨天牛引诱剂及诱捕器的林间应用技术,本研究开展了诱捕器不同悬挂高度、不同坡位与不同设置密度诱捕松墨天牛效果的调查。结果表明:诱捕器不同悬挂高度对松墨天牛的诱捕效果影响显著,随着诱捕器布设高度的增加,松墨天牛诱捕量增多,其中4.5 m处诱捕松墨天牛效果最好,诱虫量均值为245.5头/诱捕器。诱捕器不同坡位对松墨天牛的诱捕量无显著影响,其中山顶诱捕量最多,诱虫量均值72.3头/诱捕器。诱捕器设置密度加大,总诱捕量增多,林间死树株率下降,建议每6.67 hm~2(100亩)至少设置6个诱捕器。     

两种切梢小蠹危害云南松的时空生态位

【目的】云南切梢小蠹Tomicus yunnanensis KirkendallFaccoli和横坑切梢小蠹Tomicus minor(Hartig)是中国云南地区两种危害松属Pinus L.植物的钻蛀性害虫,常在云南松Pinus yunnanensis Faranch.上共同危害,通过蛀梢和蛀干为害造成树木衰弱死亡,生态破坏,带来经济损失。【方法】通过样地调查和树木解析,对两种小蠹在"梢转干"及"干转梢"时期的时间和空间生态位进行了研究。【结果】"梢转干"时期之后,横坑切梢小蠹主要分布在主干中下部,云南切梢小蠹分布在主干中上部;侧枝上主要分布着云南切梢小蠹,而横坑切梢小蠹数量很少;5月中旬进入"干转梢"阶段,两种小蠹同时进入羽化期,云南切梢小蠹在6月1日左右到达羽化高峰期,横坑切梢小蠹则比其晚10 d左右到达羽化高峰期;两种小蠹成虫转梢危害后随机分布。两种小蠹的时间和空间生态位宽度均较大,发生期较长,在云南松上分布范围较广。两种小蠹空间生态位重叠较小,在云南松上的分布趋于分离,对空间资源的需求具有较大差异;而时间生态位重叠较大,在云南松的生长季节能同时危害,且发生期较一致,危害期长。【结论】两种小蠹在空间生态位上的种间竞争强度较小,而在时间生态位上的竞争较大。通过研究比较两种切梢小蠹时间及空间生态位的特性及差异,为遥感监测云南松林的生物灾害提供了支撑依据。     

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%。     

松墨天牛在秦巴林区不同寄主上的危害规律

松墨天牛Monochamus alternatus是次期性蛀干害虫,也是松材线虫病的主要传播媒介,廓清该害虫在秦巴林区不同寄主上的危害程度和发生规律,对于控制松材线虫病的扩散蔓延具有重要意义.本研究对秦巴林区遭受松材线虫病严重危害的3种主要松树(油松Pinus tabuliformis、华山松P.armandii和马尾松P.massoniana)进行了冬季疫木野外解析,并在统计不同胸径、不同高度疫木树干上松墨天牛侵入孔和幼虫数量的基础上,采用聚集度指标分析方法,对该害虫在不同寄主上的危害差异进行了比较研究.结果表明,松墨天牛在3种寄主上的危害程度具有显著差异,以华山松受害最重,其次分别为马尾松和油松;越冬幼虫在油松上主要危害皮下1～2 cm的边材;在华山松和马尾松上危害比较多样,以髓心部位受害最重,其后依次为心材、边材和树皮;在油松和华山松上,松墨天牛主要在树干7m以下部分危害,而在马尾松上主要危害树干7m以上部分,且虫口数量均与寄主胸径呈显著正相关.松墨天牛侵入孔和越冬幼虫在不同寄主树干上均呈聚集性分布.本研究揭示了松墨天牛在秦巴林区3种主要寄主上的危害规律,对于进一步开展大尺度地理范围松墨天牛的寄主选择性及危害规律研究提供了基础信息,也为秦巴林区松墨天牛的有效防治和松材线虫病的蔓延控制提供了新的重要信息.     

Acetophenone superior to verbenone for reducing attraction of western pine beetle Dendroctonus brevicomis to its aggregation pheromone

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.     

Integration of visual and olfactory cues of hosts and non-hosts by three bark beetles (Coleoptera: Scolytidae)

Abstract.  1. There has been a long-standing pre-occupation with how phytophagous insects use olfactory cues to discriminate hosts from non-hosts. Foragers, however, should use whatever cues are accurate and easily assessed, including visual cues.
2. It was hypothesised that three bark beetles, the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, the Douglas-fir beetle (DFB), D. pseudotsugae Hopkins, and the western balsam bark beetle (WBBB), Dryocoetes confusus Swaine, integrate visual and olfactory information to avoid non-host angiosperms (e.g. paper birch, trembling aspen), that differ in visual and semiochemical profile from their respective host conifers (lodgepole pine, Douglas-fir, interior fir), and tested this hypothesis in a series of field trapping experiments.
3. All three species avoided attractant-baited, white (non-host simulating) multiple-funnel traps, and preferred attractant-baited black (host-simulating) traps. In experiments combining white, non-host traps with non-host angiosperm volatiles, bark beetles were repelled by these stimuli in an additive or redundant manner, confirming that these species could integrate visual and olfactory information to avoid non-host angiosperms while flying.
4. When antiaggregation pheromones were released from white traps, the DFB and MPB were repelled in an additive-redundant manner, suggesting that beetles can integrate diverse and potentially anomalous stimuli.
5. The MPB demonstrated the most consistent visual preferences, suggesting that it may be more of a 'visual specialist' than the DFB or WBBB, for which visual responses may be more contingent on olfactory inputs.     

Plant volatiles moderate response to aggregation pheromone in Colorado potato beetle

Abstract:  The orientation of the Colorado potato beetle, Leptinotarsa decemlineata , to a male-produced aggregation pheromone, ( S )-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol, a three-component plant attractant blend [comprised of ( Z )-3-hexenyl acetate + (±)-linalool + methyl salicylate], and other potato volatiles (nonanal and 2-phenylethanol) were tested. All compounds were previously shown to be active in coupled gas chromatography/electroantennogram experiments. Both the three-component plant attractant blend and 2-phenylethanol were attractive to adult beetles. While male beetles oriented preferentially to both plant attractants vs. a control, females showed little preference. Combining the plant attractants with the pheromone resulted in sexually dimorphic responses similar to those seen with either plant attractant alone. Addition of nonanal abolished the sexually dimorphic response to the pheromone + 2-phenylethanol blend; the new three-component blend was attractive to both sexes. In both laboratory bioassays and field experiments, a combination of the pheromone + the three-component plant attractant was preferred over the plant attractant alone. Thus, it seems likely that combinations of pheromone + plant volatiles may be the most efficacious for field use.     

Nonhost angiosperm volatiles and verbenone disrupt response of western pine beetle, Dendroctonus brevicomis (Coleoptera: Scolytidae), to attractant-baited traps

Nonhost angiosperm volatiles and verbenone were tested for their ability to disrupt the response of western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae), to attractant-baited multiple funnel traps. Verbenone significantly reduced attraction; however, no difference was observed between 4 and 50 mg/24-h release rates. Combinations of six bark volatiles (benzyl alcohol, benzaldehyde, trans-conophthorin, guaiacol, nonanal, and salicylaldehyde), three green leaf volatiles [(E)-2-hexenal, (E)-2-hexen-1-ol, and (Z)-2-hexen-1-ol], and the nine compounds combined did not significantly reduce D. brevicomis response to attractant-baited traps. However, a significant effect was observed when the bark and green leaf volatiles were combined with verbenone. The nine nonhost angiosperm volatiles (NAVs) significantly augmented the effect of both release rates of verbenone, reducing trap catches to levels significantly below that of either release rate of verbenone alone. trans-Conophthorin, a compound reported to have behavioral activity in a number of other scolytids, was not critical to the efficacy of our NAV blend. Our results suggest that the addition of nonhost angiosperm volatiles to verbenone could be important for developing successful semiochemical-based management techniques for D. brevicomis.     

Field response of non‐target beetles to Ips sexdentatus aggregation pheromone and pine volatiles

Although mass trapping cannot be a definitive control measure, it is one of the few ones available to contain the destruction of millions of cubic metres of conifer forests perpetrated every year worldwide by bark beetles. However, using bark beetle aggregation pheromones during both monitoring and control programs may negatively affect other saproxylic insects. The aim of this study was to describe the response of both Ips sexdentatus and its saproxylic beetle associates, especially predators, to traps baited with a commercial blend of I. sexdentatus aggregation pheromone. Furthermore, the usefulness of adding pine volatiles, such as (?)‐α‐pinene and ethanol, to the pheromone was discussed. The commercial blend proved to be attractive to I. sexdentatus adults, both when used alone and together with pine volatiles. Pheromone attractiveness, however, was lessened by the addition of the volatiles. The pheromone blend proved to be attractive to Thanasimus formicarius, as well as to other predator species. Overall, although during our study, traps baited only with (?)‐α‐pinene and ethanol attracted some predator specimens, I. sexdentatus pheromone traps were more attractive. Our study confirms that calendar differences in flight activity between the bark beetle and its predators are substantial; therefore, they should be taken into account when planning control measures. According to our data, the commercial blend of I. sexdentatus pheromone seems to be the most effective, among the baits used, in catching I. sexdentatus adults, while reducing the impact on T. formicarius.     

Sound production in scolytidae: 'rivalry' behaviour of male Dendroctonus beetles

Intrasex response of two males at the gallery of an attractive female included ‘rivalry’ stridulation that was distinct in certain acoustic properties from chirps evoked by the female attractant. With the southern pine beetle, Dendroctonus frontalis, comparison of chirps evoked by natural and synthetic chemostimulus confirmed that myrtenol is part of the female attractant, that verbenone is multifunctional according to its concentration, and that endo-brevicomin has a rivalry function as well as its anti-aggregative effect. Considerable acoustic specificity was apparent in tested chirps of three bark beetles.     

Semiochemical emission from individual galleries of the southern pine beetle, (Coleoptera: Curculionidae: Scolytinae), attacking standing trees

We collected, identified, and quantified volatiles arising from individual gallery entrances of the monogamous bark beetle Dendroctonus frontalis Zimmermann. Samples were collected while the insects were mass attacking mature loblolly pines (Pinus taeda L.) in an established infestation in western Mississippi, 1 August through 3 October 2005. Following volatile sample collection, the entrances were dissected and categorized according to those that 1) contained a solitary female (the gallery initiating sex), 2) contained a pair that had not yet produced an egg gallery, 3) led to an egg gallery with niches and/or eggs, or 4) represented failed attacks (either abandoned or containing dead beetles). The greatest mean release rate of the female-produced aggregation pheromone components frontalin (74 ng/h) and trans-verbenol (0.35 microg/h) was detected from entrances of solitary females, whereas the highest mean quantities of the male-produced multifunctional pheromone components endo-brevicomin (18 ng/h) and verbenone (0.15 microg/h) were detected from entrances of preoviposition beetle pairs. Alpha-pinene, a host-produced monoterpene that functions as a synergist for the aggregation attractant for D. frontalis, was detected from entrances of solitary females and preoviposition pairs at a rate of 0.6 mg/h, or 3-4 orders of magnitude greater than the insect-produced components of the attractant. Our results indicate that the release rates of pheromone components used in published field studies of the chemical ecology of D. frontalis (generally > 0.1 mg/h) represent thousands of 'attack equivalents' or production rates on the scale of a beetle mass attack on a single host. Additionally, our data suggest that the loss in attractiveness of host tissue fully colonized by D. frontalis is because of the disappearance of attractants rather than an increase in inhibitors.     

不同诱捕技术对松褐天牛的诱捕效果

通过不同引诱剂、不同诱芯、不同诱捕器和不同缓释量对松褐天牛的诱捕试验,结果表明,4种引诱剂对松褐天牛都有一定的引诱效果.其中,引诱剂MA2K 05的效果最好,引诱活性平均为26.3头/诱捕器,对其它鞘翅目和半翅目昆虫也有引诱作用;引诱剂MA2K 13活性次之,平均21.3头/诱捕器;MA2K 11最弱,平均13.8头/诱捕器.3种诱芯A、B和C的引诱效果分别为14.73、4.25和20.3头/诱捕器,其中诱芯C内引诱剂总量为诱芯A或诱芯B的2.5倍,且诱芯C内的引诱剂3～5 d需添加一次,而诱芯A和诱芯B的引诱活性能持续1个月以上,因此,诱芯B较为理想.宣州诱捕器引诱效果显著高于日式诱捕器,分别为36.4和9.7头/诱捕器.不同剂量诱捕结果表明,随着诱芯缓释量的增加,诱捕效果也相应提高,当剂量从20 ml上升至80 ml时,诱捕效果增加不显著;当诱剂达120 ml时,引诱效果显著增加.     

Ophiostomatoid fungi associated with hardwood-infesting bark and ambrosia beetles in Poland: Taxonomic diversity and vector specificity

Fungi in the orders Ophiostomatales and Microascales (Ascomycota), often designated as ophiostomatoid fungi, are frequent associates of scolytine bark and ambrosia beetles that colonize hardwood and coniferous trees. Several species, e.g., Ophiostoma novo-ulmi, are economically damaging pathogens of trees. Because little is known regarding the ophiostomatoid fungi in Europe, we have explored the diversity of these fungi associated with hardwood-infesting beetles in Poland. This study aims to clarify the associations between fungi in the genera Ambrosiella, Graphium (Microascales), Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in hardwood ecosystems. Samples associated with 18 bark and ambrosia beetle species were collected from 11 stands in Poland. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for five gene regions (ITS, LSU, ßT, TEF 1-α, and CAL) and phylogenetic analyses. In total, 36 distinct taxa were identified, including 24 known and 12 currently unknown species. Several associations between fungi and bark and ambrosia beetles were recorded for the first time. In addition, associations between Dryocoetes alni, D. villosus, Hylesinus crenatus, Ernoporus tiliae, Pteleobius vittatus and ophiostomatoid fungi were reported for the first time, and Sporothrix eucastanea was reported for the first time outside of the USA. Among the species of Ophiostomatales, 14 species were in Ophiostoma s. l., two species were in Graphilbum, nine species were in Sporothrix, and seven species were in Leptographium s. l. Among the species of Microascales, three species were in Graphium, and one was in Ambrosiella. Twenty taxa were present on the beetles and in the galleries, twelve only on beetles, and four only in galleries. Bark and ambrosia beetles from hardwoods appear to be regular vectors, with ophiostomatoid fungi present in all the beetle species. Most ophiostomatoid species had a distinct level of vector/host specificity, although Ophiostoma quercus, the most frequently encountered species, also had the greatest range of beetle vectors and tree hosts. Plant pathogenic O. novo-ulmi was found mainly in association with elm-infesting bark beetles (Scolytus multistriatus, S. scolytus, and P. vittatus) and occasionally with H. crenatus on Fraxinus excelsior and with Scolytus intricatus on Quercus robur.     

Mutualism is not restricted to tree-killing bark beetles and fungi: the ecological stoichiometry of secondary bark beetles,fungi, and a scavenger

1. All bark beetles are in symbiosis with fungi. Although obligate mutualisms with fungi are common with tree-killing bark beetles (primaries), fungi associated with non-tree-killing bark beetles (secondaries) are usually dismissed as commensals. 2. Using an ecological stoichiometric approach, we show secondaries are also involved in nutrition-based mutualisms, some of which appear obligate, and that differences in symbiont provisioning efficiency have a potent effect on beetle carbon (C): nitrogen (N): phosphorus (P) ratios. 3. Some secondary beetles have high P contents and require efficient P provisioning via fungi, while others have low P contents that may allow them to exploit less efficient fungi or a broader range of species with variable efficiencies. A co-occurring scavenger that feeds on nutrient-poor bark beetle frass (excrement/boring residues) exhibited the lowest phosphorus content yet recorded for an invertebrate. 4. Our results generally support the growth-rate hypothesis that posits differences in C:P and N:P ratios in consumers are due to differential allocation of P to P-rich RNA to support growth. However, while the beetle species that accumulated the most biomass was considerably enriched in P and that with the least biomass was P-poor, one beetle species that was P-rich was also small possibly due to limitation by an element other than P. 5. Our results indicate that fungi are important to a broader range of bark beetles than previously recognised. Additional research is needed to describe how these various symbioses influence forest ecosystems via differential effects of fungi on host beetle fitness.