Reproductive strategy of the sugi bark borer,Semanotus japonicus (Coleoptera: Cerambycidae) on Japanese cedar,Cryptomeria japonica

The inner bark of Japanese cedar,Cryptomeria japonica D. Don., is the main food of the sugi bark borer,Semanotus japonicus Lacordaire, but may also be involved in resistance to attack by the borer. I used newly hatched larvae to inoculate cedar logs that had been cut 2-weeks to 12-months earlier, and undamaged living cedar trees. On living trees, all larvae were killed by resin flow from the traumatic resin canals between the outer- and inner bark or between the inner bark and cambium. In logs that were cut more than 4 months prior to inoculation, larvae were unable to complete development. In logs cut 2 weeks prior to inoculation, almost all larvae were able to reach the adult stage but they were smaller in size than adults from living trees damaged by this borer. These results suggest that poor nutrient conditions in the inner bark of logs affected development and survival of the borer. Because of its nutritional advantage, living cedars provide a better environment for the sugi bark borer. However, all larvae are killed by resin flow, suggesting that this insect is “in between” being primary and secondary with respect to living trees, or a “weak” primary insect. The sugi bark borer seems to develop early in the season so that early instar larvae encounter reduced amounts of resin flow and so that late-instar larvae feed mostly in summer when nutrient levels in the inner bark are at their highest.     

白蜡吉丁柄腹茧蜂的寄生和繁殖生物学

白蜡吉丁柄腹茧蜂Spathius agrili Yang是我国天津地区寄生白蜡窄吉丁幼虫的一种重要天敌。本研究通过林间调查并结合室内观察,测定了该寄生蜂在不同营养条件下的存活时间和不同时期的产卵量,调查了不同寄主大小对寄生蜂后代生长发育的影响,以及寄生蜂对不同深度树皮下的寄主利用情况。结果表明：不同营养条件下白蜡吉丁柄腹茧蜂的存活时间差异很大,补充20％蜂蜜水的成蜂存活时间明显延长,最长可达3个月。相同条件下雌蜂的存活时间比雄蜂略长。在补充营养的条件下,茧蜂的产卵时间最长可达8周,产卵的高蜂在羽化后第2周前后,平均每雌每周产卵量在整个产卵期内基本保持在8～12粒上下,没有大的波动。茧蜂低龄幼虫也可能分泌毒素主动攻击寄主,提高了寄生蜂后代的生存能力。寄主个体大,营养量也大,寄生其上的茧蜂幼虫成功完成发育的数量随之增加,表明寄主营养资源的多少直接影响到寄生蜂后代的生长发育和存活。白蜡吉丁柄腹茧蜂对1～6.5 mm树皮深度范围内的适龄寄主幼虫均能够寄生利用,约92％的被寄生白蜡窄吉丁幼虫个体分布于1～4 mm深度的树皮下,在3 mm厚的树皮下分布的数量最多。茧蜂数量与树皮深度大致上呈抛物线关系,理论上在树皮深度为3.97 mm处茧蜂分布数量最多。     

The impact of phloem nutrients on overwintering mountain pine beetles and their fungal symbionts

In the low nutrient environment of conifer bark, subcortical beetles often carry symbiotic fungi that concentrate nutrients in host tissues. Although bark beetles are known to benefit from these symbioses, whether this is because they survive better in nutrient-rich phloem is unknown. After manipulating phloem nutrition by fertilizing lodgepole pine trees (Pinus contorta Douglas var. latifolia), we found bolts from fertilized trees to contain more living individuals, and especially more pupae and teneral adults than bolts from unfertilized trees at our southern site. At our northern site, we found that a larger proportion of mountain pine beetle (Dendroctonus ponderosae Hopkins) larvae built pupal chambers in bolts from fertilized trees than in bolts from unfertilized trees. The symbiotic fungi of the mountain pine beetle also responded to fertilization. Two mutualistic fungi of bark beetles, Grosmannia clavigera (Rob.-Jeffr. & R. W. Davidson) Zipfel, Z. W. de Beer, & M. J. Wingf. and Leptographium longiclavatum Lee, S., J. J. Kim, & C. Breuil, doubled the nitrogen concentrations near the point of infection in the phloem of fertilized trees. These fungi were less capable of concentrating nitrogen in unfertilized trees. Thus, the fungal symbionts of mountain pine beetle enhance phloem nutrition and likely mediate the beneficial effects of fertilization on the survival and development of mountain pine beetle larvae.     

The effect of larval aggregation behaviour on larval growth of the spruce bark beetle Dendroctonus micans

1. The great spruce bark beetle Dendroctonus micans is a primary pest of spruce in Europe. It is unusual among Eurasian scolytids in that apparently healthy trees are attacked by solitary adults, but larvae feed en masse , in response to a larval aggregation pheromone.
2. The effect of brood size on larval growth was determined in experiments on detached bark, logs and living trees. A positive relationship was found between brood size and larval growth in experiments started with either eggs or larvae up to fifth instar. The relationship appeared to be independent of the effects of both preformed and induced defences in bark.
3. No evidence was found to support the hypothesis that larvae feeding in groups spend a greater proportion of time feeding. Addition of resin to egg chambers in detached bark pieces resulted in high mortality of first-instar larvae. A possible role for larval aggregation in minimizing the effects of host defences is discussed.     

Phenology and laboratory rearing procedures of an Asian longicorn beetle, Glenea cantor (Coleoptera: Cerambycidae: Lamiinae)

Clenea cantor (F.) (Coleoptera: Cerambycidae: Lamiinae) is an Asian longicorn beetle whose larvae bore under the bark of living trees of at least seven plant families and enter the wood for pupation. Here, we determined the phenology of this beetle on its natural host, kapok [Bombax ceiba L. = Cossampinus malabaricus (DC.) Merr], in an uncontrolled insectary at ambient environmental conditions, and we compared the efficiency of four larval rearing procedures at 25 +/- 2 degrees C, 75 +/- 5% RH, and a photoperiod of 14:10 (L:D) h in the laboratory. It had five generations, including an overwintering generation, a year in southern China, with overlaps between generations and no diapause. Adults were present in early March-early December; eggs in early April-early December; larvae almost year-round, and pupae in mid-February-mid-April as well as mid-May-late November. All larvae of the overwintering generation and the larvae of the fourth generation that hatched in and after mid-November overwintered. The longevity of females and males was 71.94 +/- 1.21 d and 46.87 +/- 1.11 d, respectively, and mean fecundity was 106.65 +/- 3.61 eggs. Four larval rearing procedures using kapok twigs were tested: (1) 10 neonate larvae were left in the original host twig, (2) 10 neonate larvae were removed from the original bark and transferred to a new host twig, 3) 10 neonate larvae embedded in the original bark were transferred to a new host twig, and 4) a single neonate larva embedded in the original bark was transferred to a new host twig. We observed the survival of 300 neonate larvae for each rearing procedure. Approximately 81-85% of neonate larvae successfully developed to adult stage when neonate larvae were transferred together with the original bark to new host twigs; when neonate larvae were transferred without the original bark, only approximately 38% of the inoculants became adults, and when larvae were left in original twigs, approximately 52% of them reached adult stage. Resulting adults from different rearing methods and collected from the field had similar body weight and sex ratio. In terms of time, labor, and the number of resulting adults, procedure 3 is the most effective method for maintaining a laboratory colony.     

Oviposition schedules,survivorship curves,and mortality factors within trees of two cerambycid beetles (Coleoptera: Cerambycidae), the Japanese pine sawyer,Monochamus alternatus hope,and sugi bark borer,Semanotus japonicus lacordaire

Summary Oviposition schedules under laboratory conditions, survivorship curves, and mortality factors within trees of two cerambycid beetles, Japanese pine sawyer (JPS),Monochamus alternatus Hope, and sugi bark borer (SBB),Semanotus japonicus Lacordaire, were investigated. Average longevities of reared adults of JPS were 38.1 days for males and 42.3 days for females; those of SBB were 15.7 days for males and 23.8 days for females. It was confirmed that the JPS must feed on the pine branches for full maturation after emergence, but SBB need not; they are able to lay eggs soon after emergence. The average fecundities of JPS and SBB were 32.9 and 90.5, respectively. Thus, the JPS lay fewer eggs for a long time with continuous maturation feeding, whereas the SBB lay more eggs for short time without maturation feeding. Average survivorship curves of JPS within dead pine trees in 8 pine forests were theDeevey's B type, showing a constant mortality through the pre-imaginal stages in the trees. On the other hand those of SBB in 4 cedar stands approached theDeevey's type, suggesting that the high mortality occurred at an early stage in the trees. Average mortalities of JPS between the appearance of oviposition scars and adult emergence in 8 forests ranged from 62.3% to 95.2%. Intraspecific ompetition of JPS resulting from overcrowding in dead pine trees appeared to be main mortality factor. For SBB, as most larvae were killed by resin flow in living trees, this appeared to be the main mortality factor for this species.     

果实种类及发育阶段对梨小食心虫幼虫钻蛀率和蛹重的影响

【目的】明确梨小食心虫Grapholitha molesta在寄主果实上的钻蛀率和蛹重与寄主种类和果实发育阶段的关系,为其田间预测预报和综合防控提供技术依据。【方法】在室内条件下测定了接卵后72 h梨小食心虫初孵幼虫在不同发育阶段的3个种共6个品种水果［苹果Malus pumila (嘎啦苹果), 桃Amygdalus persica (大久保毛桃、丰白毛桃和霞光油桃), 梨Pyrus bretschneideri (砀山酥梨和玉露香梨)］果实上的钻蛀率以及在不同果实状态的4个水果品种(大久保毛桃、丰白毛桃、砀山酥梨和玉露香梨)果实上72 h的钻蛀率;比较了接卵后24 h和72 h初孵幼虫在不同发育阶段的3个苹果品种(嘎啦苹果、富士苹果和金冠苹果)果实上的钻蛀率;并测定了不同发育阶段的金冠苹果、富士苹果、嘎啦苹果、砀山酥梨和丰白毛桃上的梨小食心虫蛹重。【结果】接卵后72 h梨小食心虫初孵幼虫在6个不同水果品种果实上的钻蛀率从高到低依次为：霞光油桃＞嘎啦苹果＞砀山酥梨＞玉露香梨＞大久保毛桃＞丰白毛桃;除霞光油桃外,其他5个水果品种果实的发育阶段显著影响初孵幼虫钻蛀率。对于嘎啦苹果,接卵后72 h初孵幼虫在其幼果上的钻蛀率最高(73.69%),在其着色期果实上钻蛀率最低(32.51%);在大久保毛桃、丰白毛桃、砀山酥梨和玉露香梨上,接卵后72 h初孵幼虫的钻蛀率均随果实生长发育而增加。初孵幼虫在3 个苹果品种着色期和成熟期果实上的钻蛀率随处理时间的增加而显著下降,而在其幼果上变化不显著。寄主种类及其发育阶段也显著影响梨小食心虫蛹重,成熟毛桃和梨饲养的雌、雄蛹重显著高于未成熟果实饲养的蛹重,着色期苹果不利于蛹重的增加。【结论】果实种类及发育阶段显著影响梨小食心虫初孵幼虫钻蛀率和蛹重,取食成熟期梨和桃的梨小食心虫初孵幼虫钻蛀率和蛹重显著高于取食未成熟果实的个体。     

萧氏松茎象的生活史、产卵和取食习性

萧氏松茎象Hylobitelus xiaoi是严重蛀害国外松的新害虫。在江西赣南地区两年发生一代,以幼虫在蛀道、成虫在蛹室或土中越冬。卵和蛹的发育起点温度分别为8.4℃和7.5℃,有效积温分别为215.9和345.3日·度。各虫态历期：13～28℃间,卵为52.9～11.4天;13～30℃间,蛹为60.1～16.4天; 25℃恒温下,幼虫128.9天。成虫靠爬行活动,极少飞翔。成虫具夜出性活动节律：即傍晚上树行取食、交配和扩散等活动,早晨回到树干基部或土缝中。成虫需取食松枝作为补充营养,产卵前期46.3天,产卵期 105.3天,卵产于近表土的寄主树皮内,每雌产卵35.7粒。幼虫5～7龄,以幼树危害最烈。     

Girdling by notodontid caterpillars: distribution and occurrence

Girdling insects produce a circular groove around a stem or petiole typically before ovipositing or feeding on the distal section. We documented that seven of the 11 species of notodontid caterpillars that we studied, including members of five genera in two subfamilies, chewed girdles in seven families of trees including species of birch, hickory, oak, elm, cherry, willow, and maple. The frequency of girdling varied with notodontid species, tree species, month, and year. Free-ranging final instar larvae of Schizura leptinoides on pecan (Carya illinoensis) spent 4?C11?% of their time cutting and reinspecting girdles over 5-h and 12-h observation periods. Feeding occurred proximal as well as distal to girdles, a result not expected by most hypotheses for the function of girdling. Histological examination of S. leptinoides girdles on river birch (Betula nigra) revealed that only the xylem remained intact; however, on pecan, both the xylem and phloem remained mostly uncut by the girdle. S. leptinoides larvae often rubbed their mouthparts over the surface of finished girdles, anointing them with fluid from the labial salivary glands or possibly the ventral eversible gland. After feeding, S. leptinoides and other notodontids sometimes severed the petiole even when the leaf was only partially eaten; these leaf-clipping larvae were similarly observed rubbing their mouthparts over the severed petiole stub. We propose that notodontids cut girdles and clip leaves at least in part to introduce secretions or their enzymatic products into the vascular system to suppress host defenses and/or enhance nutrition.     

Girdling affects carbohydrate-related gene expression in leaves,bark and roots of alternate-bearing citrus trees

Effects of girdling on carbohydrate status and carbohydrate-related gene expression in citrus trees were investigated. Alternate-bearing 'Murcott' (a Citrus reticulata hybrid of unknown origin) trees were girdled during autumn (25 Sep. 2001) and examined 10 weeks later. Girdling brought about carbohydrate (soluble sugar and starch) accumulation in leaves and shoot bark above the girdle, in trees during their fruitless, 'off' year. Trees during their heavy fruit load, 'on' year did not accumulate carbohydrates above the girdle due to the high demand for carbohydrates by the developing fruit. Girdling caused a strong decline in soluble sugar and starch concentrations in organs below the girdle (roots), in both 'on' and 'off' trees. Expression of STPH-L and STPH-H (two isoforms of starch phosphorylase), Agps (ADP-glucose pyrophosphorylase, small subunit), AATP (plastidic ADP/ATP transporter), PGM-C (phosphoglucomutase) and CitSuS1 (sucrose synthase), all of which are associated with starch accumulation, was studied. It was found that gene expression is related to starch accumulation in all 'off' tree organs. RNA levels of all the genes examined were high in leaves and bark that accumulated high concentrations of starch, and low in roots with declining starch concentrations. It may be hypothesized that changes in specific sugars signal the up- and down-regulation of genes involved in starch synthesis.     

Intraspecific variation in beech scale populations and in susceptibility of their host Fagus sylvatica

ABSTRACT.

• 1 Within a seed orchard in southern England, beech trees (Fagus sylvatica L.) belonging to three clones were artificially infested by introducing beech scale larvae (Cryptococcus fagisuga Lind. Homoptera: Coccidae) into small cages attached to the bark.
• 2 Some larvae developed to fecund adults on trees of two susceptible clones but all failed to develop on a third, resistant clone.
• 3 Within susceptible clones, survival of larvae on individual trees was positively related to their degree of natural infestation.
• 4 Larvae deriving from several separate trees differed significantly in their ability to survive when inoculated onto trees of susceptible clones.
• 5 Five forest trees which acted as both donors of larvae and as hosts for artificial inoculation were each inoculated with larvae from all five trees.
• 6 There was significant variation in survival of inoculated larvae both between the host trees and between sources of larvae on each host.
• 7 Survival of larvae reinoculated onto their original host was significantly higher than that of larvae originating from other trees.
• 8 Fecundity of adults on the forest trees was positively correlated with the probability of inoculated larvae surviving to the adult stage.

     

Host activity and wasp experience affect parasitoid wasp foraging behaviour and oviposition on nematode‐infected larvae of the forestry pest Hylobius abietis

1. Entomopathogenic nematodes (EPN) are currently being used as introduced biological control agents against the larvae of the native European forestry pest Hylobius abietis L. which develop under the bark of stumps and roots of newly dead conifer trees. 2. The potential for resource competition between gregarious ectoparasitoid Bracon hylobii Ratz and EPN by recording oviposition and related behaviours of B. hylobii females on EPN‐infected H. abietis larvae was investigated. Wasps did not parasitise EPN‐infected host larvae that were dead when presented, but naÏve and experienced wasps parasitised live EPN‐infected hosts. NaÏve wasps parasitised live EPN‐infected hosts significantly less frequently than healthy hosts only when the infected larvae were close to death (i.e. died during 24‐h trial). Parasitism by experienced wasps was unaffected by host infection. 3. Wasp probing and oviposition were positively associated with the amount of host movement. Preventing H. abietis larvae from chewing on bark significantly reduced parasitism by naÏve, but not experienced wasps. 4. The number of eggs per clutch was not affected by bark chewing or EPN‐infection of H. abietis larvae. 5. NaÏve and experienced B. hylobii parasitised two abnormal hosts (larvae of coleopteran Rhagium bifasciatum Fabricius and lepidopteran Galleria mellonella L.), both of which moved and chewed on bark during trials. 6. It was concluded that B. hylobii can use vibrational cues generated by host movement and feeding to locate hosts at short range and accepts unsuitable (EPN‐infected or abnormal) hosts as long as these create such cues. The implications for competition between B. hylobii and EPN and possible ways of minimising it when applying EPN are discussed.     

Inhibition of premature leaf abscission by a leafminer and its adaptive significance

We tested the possibility that a lepidopteran leafminer, Coptotriche japoniella Puplesis and Diskus, inhibits the host plant Eurya japonica Thunberg from abscising mined leaves prematurely to increase its survivorship in immature stage. We monitored abscission patterns of mined leaves with sacrificed larvae, mined leaves with living larvae, and unmined leaves from April to July 2004 and 2005 until leafminers emerged as adults. Unmined leaves rarely abscised before July. Mined leaves with sacrificed larvae fell at a constant rate after May, abscising significantly more than unmined leaves. In contrast, mined leaves with living larvae rarely fell before adult emergence; afterward they abscised rapidly. We also examined larval/pupal survivorship and mortality sources on the ground and trees after leafminers completed larval development. Leafminers on the ground suffered a higher mortality from predation than those on trees, and thus they emerged as adults on the ground less successfully. These findings suggest that the leafminer C. japoniella prevents the host plant from abscising mined leaves prematurely until adult emergence, thereby increasing their survivorship.     

平腹小蜂防治荔枝蝽象试验研究

20 0 0年 2～ 8月 ,在广西北流潮塘、荔宝、花果山等果场进行了平腹小蜂防治荔枝蝽象试验 ,总面积约2 0 hm2 ,8～ 1 0年生龙眼、荔枝树约 4 0 0 0株。根据当地荔枝蝽象的生活习性及发生规律 ,共放蜂 2次 ,结果为 :在放蜂区和对照区内 ,荔枝蝽象卵寄生天敌平腹小蜂、跳小蜂的总寄生率分别为 94 .3%和 1 8.9% ,相比效果明显 ,同时 ,果园中若虫数量显著降低 ,控制在经济危害阈值之下。     

The biology ofRoptrocerus xylophagorum [Hym.: Torymidae], with a note on its taxonomic status

The biology of the bark beetle parasitoidRoptrocerus xylophagorum (Ratzeburg) from Georgia, U.S.A., was studied under controlled conditions in Australia. Parasitoids were presented withIps grandicollis Eichhoff in the isolated bark ofPinus radiata D. Don. Females lived up to 24 days at 24°C, and could parasitize up to 11 hosts in a single day. Usually only 1 egg was laid on each paralyzed host. Both larvae and pupae were parasitized, but the former appeared to be preferred. The species was arrhenotokous, and tended to produce more males when parasitizing smallerIps larvae. Males and females required 158D^o and 179D^o respectively, above a threshold of 13.8°C, to complete development, and their size was dependent on the host stage. Insects in a 2nd culture ofRoptrocerus from California differed in appearance, although supposedly being the same species. A preliminary cross-breeding experiment provided evidence that the 2 cultures are reproductively isolated.     

Digestion of Bacillus thuringiensis var. israelensis spores by larvae of Aedes aegypti.

The larvicidal activity of Bacillus thuringiensis var. israelensis against mosquitoes and the blackfly is included in parasporal crystalline bodies which are produced during sporulation. Following ingestion, the crystals are solubilized in the larval midgut and induce death within a short time; the spores germinate in the dead larvae and complete a growth cycle. The fate of the spores in surviving live larvae was elucidated by using a nonlarvicidal B. thuringiensis var. israelensis mutant. When introduced as the only food source, spores of this mutant support development to the adult stage of newly hatched Aedes aegypti larvae at a rate directly related to spore concentration. The conclusion that spores of B. thuringiensis var. israelensis are digested in the larval gut was substantiated by following the incorporation of [35S]methionine-labeled spores into larval tissues.     

Spatial and temporal dynamics of bark beetles in Chinese white pine in Qinling Mountains of Shaanxi Province, China

Spatial and temporal dynamics of bark beetles in single tree trunks of Pinus armandi were studied in Qinling Mountains, Shaanxi Province, China. Ten species of engraver bark beetles attacked from healthy to withered Chinese white pines, but seven species were commonly detected every year in Qinling forest ecosystem. Dendroctonus armandi and Hylurgops longipilis were common species at the lower of trunks, and Ips acuminatus, Polygraphus sinensis, and Pityogenes japonicus primary distributed in the middle of trunks, whereas population densities of Cryphalus lipingensis and C. chinlingensis centralized at the upper trunks and branches of Chinese white pines. On the time series, D. armandi, as a dominant species in Chinese white pines of Qinling forest ecosystem, mainly attacked healthy and weakened trees and cooperated with blue stain fungus that resulted in the declining abruptly resistance and triggered the secondary bark beetles to attack the infected or withered host trees. Attacking and colonizing phenology of bark beetles in Qinling forest ecosystem are caused by complex interactions among spatial and trophic competition and cooperation and exhibit particular spatial and temporal patterns. Our results support the view that competition and cooperation within bark beetles are a critical factor to influence bark beetles spatial and temporal distribution, and stability of bark beetles' ecosystem, D. armandi, I. acuminatus, P. japonicus, P. sinensis, C. lipingensis, C. chinlingensis, and H. longipilis in Chinese white pine of Qinling forest ecosystem.     

中国白蜡窄吉丁研究进展

白蜡窄吉丁Agrilus planipennis Fairmaire是近年来发生和影响比较严重的国际性检疫害虫,主要危害白蜡属(Fraxinus spp.)树木。它以幼虫在树木的韧皮部、形成层和木质部浅层蛀食,从而切断树木的营养输导组织,导致树木衰弱死亡。为了深入了解该害虫,探索合理的治理策略,本文对国内外有关白蜡窄吉丁的生物学特性,包括生活习性、生活史、分布与危害、寄主范围等方面以及防治技术的研究进展进行了系统总结,并讨论了白蜡窄吉丁今后的研究方向和研究趋势。     

Maternal transfer of cadmium tolerance in larval Oreochromis mossambicus

Exposing female tilapia to Cd did not affect reproduction and egg quality, nor the survival of their offspring. The LT ₅₀ of Cd-exposed larvae (within 24 h post hatching) from Cd-treated female Oreochromis mossambicus (mean ±S.E.=10·9±0·5 days, n =4) was greater than that of Cd-exposed larvae from control females (6·9± 1·2 days, n =4). A substantial amount of metallothionein mRNA (MT mRNA) was found in both oocytes and newly hatched larvae from Cd-treated females, but MT mRNA levels were low in newly fertilized eggs. The amount of MT mRNA was very low in all these stages in the control group. Cadmium could not be detected at any stage for either control or Cd-treated group, and metallothionein protein levels were also very low in both groups. The early appearance of MT mRNA in oocytes and newly hatched larvae from Cd-treated females may result in early translation after hatching and explain their tolerance to Cd.