一种花瘿蚊(双翅目:瘿蚊科)与其寄主植物对萼猕猴桃Actinidia valvata的相互关系(英文)

猕猴桃属植物Actinidia spp,自然分布于中国的亚热带地区。对萼猕猴桃A.valvata的花芽受Pseudasphond ylia 瘿蚊属一未知种的寄生而形成花芽虫瘿,这种花芽瘿由于近年来在制药工业上的应用而受到重视。在中国中南地区研究对萼猕猴桃—瘿蚊的相互关系过程中,我们的记载表明该造瘿昆虫在一定情形下可能改变其寄主植物的雌雄异株之生殖模式。野外调查与实验证明寄主植物受寄生而形成虫瘿的比例很高。但虫瘿密度却于不同沟谷间,或同一沟谷内不同植株间有异。在二条沟谷内,92％和75％植株分别被寄生,而在第3条沟谷内没有植株受寄生。受寄生的雄性植株只产生虫瘿,而受寄生的雌性植株则产生正常果与虫瘿。有迹象显示当寄主植株有虫瘿形成时其正常果数量也更多。作者认为这可能是昆虫诱导功能上雌雄异株植物形成雄性异株雌雄同株之生殖模式的少数例子     

Detectability of the emerald ash borer (Coleoptera: Buprestidae) in asymptomatic urban trees by using branch samples

The emerald ash borer, Agrilus planipennis Fairmaire, is an exotic invasive insect causing extensive mortality to ash trees, Fraxinus spp., in Canada and the United States. Detection of incipient populations of this pest is difficult because of its cryptic life stages and a multiyear time lag between initial attack and the appearance of signs or symptoms of infestation. We sampled branches from open-grown urban ash trees to develop a sample unit suitable for detecting low density A. planipennis infestation before any signs or symptoms are evident. The sample unit that maximized detection rates consisted of one 50-cm-long piece from the base of a branch ≥6 cm diameter in the midcrown. The optimal sample size was two such branches per tree. This sampling method detected ≈75% of asymptomatic trees known to be infested by using more intensive sampling and ≈3 times more trees than sampling one-fourth of the circumference of the trunk at breast height. The method is less conspicuous and esthetically damaging to a tree than the removal of bark from the main stem or the use of trap trees, and could be incorporated into routine sanitation or maintenance of city-owned trees to identify and delineate infested areas. This research indicates that branch sampling greatly reduces false negatives associated with visual surveys and window sampling at breast height. Detection of A. planipennis-infested asymptomatic trees through branch sampling in urban centers would provide landowners and urban foresters with more time to develop and implement management tactics.     

THE RELATIONSHIP BETWEEN A FLOWER GALL MIDGE PSEUDAS-PHONDYLIA SP. (DIPTERA: CECIDOMYIIDAE) AND ITS HOST PLANT ACTINIDIA VALVATA*

Abstract Kiwifruit plants, Actinidia sp., are native to subtropical China. The flower-bud gall of A. valvata, which is induced by an undescribed gall midge in the genus Pseud as phond ylia, is valued by the pharmaceutical industry. When studying the biology of the Actinid ia/Pseud as phond ylia interaction in Central-south China we found evidence suggesting that under certain circumstances the gall insect modifies the reproductive mode of the dioecious host plant. Surveys and field experiments in the National Hupingshan Natural Reserve showed a high frequency of galled trees. The density of galled trees varied among valleys and among trees within the valleys. In two valleys, 92% and 75%, respectively, of all trees were attacked, while in a third valley no trees were attacked. When infested, staminate tree only produced galls, whereas pistillate plants produced normal fruits as well as galls. Gall shape differed between male and female trees. Trees with galls tended to produce more fruits than treea without galls. We speculate that this is one of a few documented examples of an insect that induces androdioecy in an otherwise functionally dioecious plant.     

The role of host tree condition in attack of white oaks by the twolined chestnut borer,Agrilus bilineatus (Weber) (Coleoptera: Buprestidae)

Summary The twolined chestnut borer, Agrilus bilineatus (Weber) (Coleoptera: Buprestidae), attacks stressed oaks (Quercus spp.) and is associated with extensive mortality of trees in the eastern deciduous forests of North America. We examined host location by the insect and subsequent host mortality in experimentally stressed trees. A. bilineatus adults were able to rapidly and specifically locate stressed oak trees. Up to 160 beetles per week were captured on sticky band traps on the trunks of stressed trees, while beetles rarely landed on unstressed control trees. This suggests that adult borers have an acute perception of host tree quality, and that this perception is from a distance. One mechanism of host location may be detection of volatile compounds produced by stressed trees.The condition of the host tree appears to regulate both beetle attraction and successful colonization. Mortally wounded (xylem-girdled) trees attracted beetles only until the cambium died. Xylem-girdled trees were attacked early in the beetle flight season, but larvae did not survive to emerge as adults from these trees. In contrast, phloemgirdled trees continued to attract beetles throughout the flight period. Phloem-girdled trees which were heavily attacked by A. bilineatus died late in the season in which they were attacked. Lightly attacked trees survived until the following growing season, and were then heavily attacked and killed. In one stand, phloem-girdled trees were not attacked, healed over the girdling wounds and were still alive three years after girdling. These results indicate that oak trees are only attractive to A. bilineatus within a narrow range of physiological conditions following stress but prior to mortality. A. bilineatus appears to be a proximate agent of mortality in stressed oaks in eastern North America.This paper (85-7-8-216) resulted from a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director     

Ecosystem engineering and manipulation of host plant tissues by the insect borer Oncideres albomarginata chamela

Ecosystem engineering by insect herbivores occurs as the result of structural modification of plants manipulated by insects. However, only few studies have evaluated the effect of these modifications on the plant responses induced by stem-borers that act as ecosystem engineers. In this study, we evaluated the responses induced by the herbivory of the twig-girdler beetle Oncideres albomarginata chamela (Cerambycidae: Lamiinae) on its host plant Spondias purpurea (Anacardiaceae), and its relationship with the ecosystem engineering process carried out by this stem-borer. Our results demonstrated that O. albomarginata chamela branch removal induced the development of lateral branches increasing the resources needed for the development of future insect generations, of its own offspring and of many other insect species. Detached branches represent habitats with high content of nitrogen and phosphorous, which eventually can be incorporated into the ecosystem, increasing nutrient cycling efficiency. Consequently, branch removal and the subsequent plant tissue regeneration induced by O. albomarginata chamela represent key mechanisms underlying the ecosystem engineering process carried out by this stem-borer, which enhances arthropod diversity in the ecosystem.     

柑桔爆皮虫羽化孔的空间分布

通过调查柑桔爆皮虫成虫羽化孔的分布,经空间分布型检验和聚集度指标的测定以及Taylor幂法则和m*- m（Iwao）回归分析,结果表明,柑桔爆皮虫的羽化孔在柑桔树树体内和桔园内均呈聚集分布: 在枯树内呈负二项分布,在半枯树内呈负二项分布或奈曼A型分布,在桔园内呈负二项分布,在树体内和桔园内分布的基本成分均为为个体群,个体间相互吸引。树势较差的柑桔树容易受柑桔爆皮虫危害,在树势强的树体内不能完成世代发育。因此,柑桔爆皮虫采用多次聚集攻击的策略攻击寄主。在桔园内聚集危害部分寄主,在树体内聚集危害寄主主枝的中下部,主枝的死亡导致整株树势下降,下一代虫源进而再次攻击寄主,在树势下降的树体内柑桔爆皮虫完成世代发育并羽化出孔,成虫继续为害健康的柑桔树。     

Potential management strategies for the linden borer (Coleoptera: Cerambycidae) in urban landscapes and nurseries

The linden borer, Saperda vestita Say (Coleoptera: Cerambycidae), is a native insect species that is common throughout north central and northeastern North America. Over the past decade, increasing occurrence of damage associated with the linden borer has been reported on Tilia spp. in city street trees and nurseries throughout Wisconsin, probably because of increased use of these trees. Our objective was to gain a better understanding of the seasonal biology and potential management strategies for this important pest. We evaluated the effectiveness of three systemic insecticides, imidacloprid, thiamethoxam, and disulfoton, and a mechanical control method of chipping linden borer-infested wood as a means of reducing S. vestita larval survival, subsequent emergence, and oviposition. Autumn and spring soil injections of imidacloprid to linden borer-infested Tilia cordata'Greenspire' nursery stock (< 11.4 cm in diameter at breast height [dbh]) provided >90% control. Autumn soil injections of imidacloprid and thiamethoxam and a spring granular soil application treatment of disulfoton applied to larger (>22 cm dbh) Tilia spp. did not effectively control linden borer at the application rates tested. Chipping infested Tilia spp. effectively destroyed linden borer larvae, pupae, and adults. Arborists and landscape managers should consider chipping felled Tilia spp. trees infested with S. vestita to prevent adults from potentially attacking nearby susceptible trees.     

Branch regeneration induced by sever damage in the brown alga <Emphasis Type="Italic">Dictyota dichotoma</Emphasis> (dictyotales,phaeophyceae)

Tissue wounds are mainly caused by herbivory, which is a serious threat for macro-algae, and brown algae are known to regenerate branches or buds in response to wounding. In the present paper, we describe a branch regeneration system, induced by sever damage, in the brown alga Dictyota dichotoma. Segmentations of juvenile thalli induced branch regenerations unless explants possessed apical cells. Apical excisions in distinct positions elucidated that disruption of an apical cell or disconnection of tissue with an apical cell triggered the branch regeneration. Furthermore, spatial positions of regenerated branches seemed to be regulated by the apical region, which was assumed to generate inhibitory effects for lateral branch regeneration. Mechanical incision, which disrupted tissue continuity with the apical region, induced branch regeneration preferentially below the incision. Although we were unable to identify the candidate inhibitory substance, our results suggested that the apical region may have an inhibitory effect on lateral branch regeneration. Additionally, observations of branch regeneration showed that all epidermal cells in D. dichotoma possess the ability to differentiate into apical cells, directly. This may be the first report of algal transdifferentiation during the wound-stress response.     

Hybrid aspen is not preferred by the large poplar borer (Saperda carcharias)

An industrially valuable tree, aspen, suffers from several fungal diseases and insect pests such as the large poplar borer (Saperda carcharias). The role of the beetle as a pest of aspen and hybrid aspen was investigated in five aspen and three hybrid aspen stands in Finland. Approximately 50% of the trees in the study had signs of the large poplar borer. Of these trees, 5% had insect exit holes. Approximately 70% of the trees with larval galleries had only one or two larval galleries. The trees with larval galleries were on average 2 m shorter than those without larval galleries. No significant difference could be detected in the diameter growth between these two groups. The proportion of decay was greater in hybrid aspen (27%) than in aspen (14%). These results show that the large poplar borer is an important pest of both aspen and hybrid aspen in Finland. No significant difference was observed between the aspen and hybrid aspen stands in the number of trees with larval galleries. Hybrid aspen therefore does not appear to be more sensitive to damage caused by the large poplar borer. Thus, a change from hybrid aspen to regular aspen in aspen cultivation is unnecessary, presuming that healthy saplings and an optimal rotation time are used.     

The transition from vegetative to fertile tissue in Fucus vesiculosus

At various stages of receptacle development, segments of Fucus vesiculosus thallus subtending the fertile tips have been grown in culture. At the times of gamete maturation and gamete shedding a number of both reproductive and vegetative branches are regenerated from the wound callus. This is the only region of the Fucus thallus which has been found capable of regenerating fertile receptacles. The effects of a number of growth regulatory substances were studied. 1-naphthoxyacetic acid stimulated budding but no substance increased the proportion of fertile branches. Extracts prepared from mature receptacles did not induce the regeneration of fertile branches from vegetative thallus, but they markedly inhibited the regeneration of any branches. Subsequent estimations of the growth regulatory substances in the receptacles showed that there was a marked increase in growth inhibitors during gamete development. Growth stimulatory substances were also present but these were masked in crude extracts by the amount of inhibitors.     

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.     

警惕果树重大害虫——苹楔天牛

苹楔天牛Saperda candida Fabricius(鞘翅目Coleoptera:天牛科Cerambycidae)原产北美,主要危害果树,300多年来被认为是原产地果园最具毁灭性的害虫。2008年该害虫首次传入欧洲(德国费马恩岛),因而受到许多国家的重视。该害虫的寄主植物苹果、梨、李、山楂等果树在我国种植非常广泛,具有十分重要的经济价值。该天牛会随着寄主植物的引进、调运进行远距离传播,我国应加强对该害虫的检疫。文章就其形态特征、危害特点、生物学特性及潜在风险作一阐述。     

Evaluation of transgenic Bt corn for resistance to the Asian corn borer (Lepidoptera: Pyralidae)

The Asian corn borer, Ostrinia furnacalis (Guenée), is the most important insect pest on corn in China. Bt transgenic corn provides a new tool for Asian corn borer control. Monsanto's YieldGard Bt transgenic corn expressing Cry1Ab protein, and a non-Bt control, were evaluated in Beijing. Laboratory bioassays were carried out by exposing neonates to an agar-free diet containing Bt corn whorl leaves, tassels, and anthers, or by exposing neonates directly to fresh silk and pollen. These are the tissues initially attacked by neonates in the field. All of these tissues, with the exception of pollen, contained sufficient insecticidal protein to kill > or = 95% of larvae within 7 d. Surviving larvae had also not grown beyond first instar and weighed < or = 0.1 mg. Although larvae feeding on Bt corn pollen were significantly smaller than those on non-Bt corn pollen, there was no significant difference in mortality. Field trials were also conducted with artificial infestations of Asian corn borer at mid whorl, late whorl, and silking stages. Damage ratings and number of larvae surviving per plant indicated that Bt corn was highly resistant to Asian corn borer. Therefore, YieldGard offers the potential for season-long protection against first- and second-generation Asian corn borer.     

Population structure of the tree Peltogyne purpurea (Cesalpinaceae) in an altered forest at Osa Peninsula, Costa Rica

The regeneration of the rain forest tree Peltogyne purpururea Pittier after selective logging was studied in Mogos, Osa Peninsula, Costa Rica. The distribution of all adult trees of P. purpurea according to diameter at breath height (dbh) categories revealed that the distribution of the adult trees followed a bell-shaped curve. The largest number of individuals was found in the 70 to 80 cm dbh category. We did not find any significant differences in the distribution of saplings around seed-producing trees. There were similar numbers of saplings in the four transects established around each reproductive tree following the four cardinal directions. Overall, the majority of the saplings were found in the first meters around each seed-producing tree. There was another peak in the number of saplings at the distance where the crown of the tree ended. Logging can negatively affect the regeneration of P. purpurea.     

Efficacy of systemic insecticides for protection of loblolly pine against southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae)

We evaluated the efficacy of the systemic insecticides dinotefuran, emamectin benzoate, fipronil, and imidacloprid for preventing attacks and brood production of southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae) on standing, stressed trees and bolt sections of loblolly pine, Pinus taeda L., in eastern Texas. Emamectin benzoate significantly reduced the colonization success of engraver beetles and associated wood borers in both stressed trees and pine bolt sections. Fipronil was nearly as effective as emamectin benzoate in reducing insect colonization of bolts 3 and 5 mo after injection but only moderately effective 1 mo after injection. Fipronil also significantly reduced bark beetle-caused mortality of stressed trees. Imidacloprid and dinotefuran were ineffective in preventing bark beetle and wood borer colonization of bolts or standing, stressed trees. The injected formulation of emamectin benzoate was found to cause long vertical lesions in the sapwood-phloem interface at each injection point.     

Winter starch reserves of white oak as a predictor of attack by the twolined chestnut borer,Agrilus bilineatus (Weber) (Coleoptera: Buprestidae)

Summary The twolined chestnut borer, Agrilus bilineatus (Weber) (Coleoptera: Buprestidae), attacks oaks (Quercus spp.) and is associated with extensive mortality of trees in the eastern deciduous forests of North America. We tested the hypothesis that winter starch reserves of oak roots are an indicator of tree vigor and that only trees low in stored starch would be attacked by A. bilineatus. We measured the levels of stored starch in the roots of 200 non-infested healthy white oaks during the dormant season and determined their correlation with A. bilineatus attacks the following spring. There was a significant increase in A. bilineatus captures on sticky traps with a decrease in winter starch reserves. Trees low in stored starch that were also stressed by phloem-girdling attracted 3.7 times as many beetles as did non-girdled trees that were low in starch. However, non-girdled trees that had low winter starch reserves were also attacked. Only oaks that had had extremely low winter root starch reserves (<5mg/g dry weight of root sapwood tissue) were heavily attacked by A. bilineatus and subsequently died. One third of non-girdled low starch trees and 67% of phloem-girdled low starch trees died, whereas none of the trees with root starch >5 mg/g dry wt died. These results indicate that winter starch reserves are a good predictor of A. bilineatus attack.The investigation reported in this paper (No. 87-7-8-118) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director     

Pollen limitation and fruit abortion in a declining rare tree,the Eurasian yew (Taxus baccata L.): A reproductive cost of ecological marginality

Populations of rare tree species such as the dioecious and anemophilous yew (Taxus baccata) are especially prone to extinction if they occupy marginal habitats. This is the case of yew populations growing in Mediterranean mountains under dry climate and a severe anthropogenic disturbance regime, which show insufficient regeneration. We examined two of the likely mechanisms driving this population decline. The study was conducted in a central Spanish yew population in 2005 and 2006. On one hand, we tested for the effect of the amount of pollen received by female flowers by means of a pollen addition experiment. On the other hand, we tested for the effect of initial fruit set on abortion and mature fruit production. Finally, we evaluated the effect of the spatial arrangement of male and female yew trees on realized fecundity. The success of fertilization and fruiting in the experimental population was pollen-limited. Female trees aborted ca. 70% of the fruit set in both years and treatments. Fruit set was significantly influenced by the females' neighbourhood, with fecundity decreasing exponentially with distance to the nearest male in both years. Overall, our results indicate that factors associated with ecological marginality have a strong influence on yew performance.     

狐尾藻属狭域种和广布种断枝的生长与再生能力比较研究

对比研究了广布种穗花狐尾藻(Myriophyllum spicatum L.)和狭域种扬子狐尾藻(M. oguraense Mikisubsp. yangtzense Wang)不同长度(5、10 和15 cm)和不同位置(顶枝、中枝和底枝)断枝的生长和再生能力。研究结果显示, 两物种由断枝生长所形成植株的总生物量、分枝生物量、分枝数均随断枝长度的增加而增大;在由不同位置的断枝生长所形成的植株中, 顶枝所形成植株的总生物量最大, 中枝所形成植株的分枝生物量、分枝数和平均分枝长最大。由断枝所形成植株的总生物量、分枝生物量、分枝数、平均分枝长和新分枝所处位置在种间均存在显著差异, 穗花狐尾藻顶枝和中枝的生物量较大, 顶枝所产生的分枝位于断枝基部; 扬子狐尾藻的分枝生物量、分枝数及平均分枝长较大, 新产生的分枝多位于断枝顶端附近。研究结果表明穗花狐尾藻和扬子狐尾藻断枝的再生对策不同, 前者是增加对断枝总生物量的投资, 而后者是增加对断枝产生新分枝的投资。研究结果可为进一步开展水生植物广布种与狭域种的生活史对策研究提供资料, 也为湿地物种多样性保护与管理提供科学指导       

Improved protoplast culture and stability of cytoplasmic traits in plants regenerated from leaf protoplasts of cauliflower (Brassica oteracea ssp.botrytis)

Nearly 1000 plants have been regenerated from leaf protoplasts of two cauliflower (Brassica oleracea ssp.botrytis) alloplasmic inbred lines. One line (7642A) carried the Ogura (R1) cms cytoplasm derived from radish; the other line (7642B) carried a normalBrassica cytoplasm and was the fertile maintainer for the cms line. The majority of regenerated plants displayed normal vegetative morphology; they formed normal cauliflower heads and retained the floral characteristics of seed-grown plants from which they were derived. We found no change in either male sterility or in the low temperature-induced chlorosis associated with the 7642A line. Mitochondrial DNA analysis by hybridization with five cloned mtDNA probes revealed no apparent alteration in 75 regenerated plants of both lines. These results indicate that cytoplasmic traits inBrassica oleracea are stable after one cycle of in vitro culture and regeneration.     

Carbon allocation to volatiles and other reproductive components in male Ficus carica (Moraceae)

Volatile compounds are often mediators of plant-pollinator interactions. Their emission is presumed to be costly, but this cost has seldom been quantified. Figs of Ficus carica (a dioecious species) release volatile compounds when receptive, thus attracting the agaonid wasp Blastophaga psenes. In dioecious fig species, wasps lay eggs inside male figs and pollinate female ones. For a male tree, we estimated carbon allocation to reproduction using the annual growth module (AGM) as the unit of measurement. Over the growing season, leaf and fig carbon exchange and construction costs were measured, as well as carbon investment in stamens, provisioning pollinators, and biosynthesis and release of volatile compounds. Representativity of the tree studied was evaluated by measuring some of these parameters on seven other male fig trees. The results show that 7.6-16.4% of the carbon assimilated by leaves and figs was invested in reproduction. Of the carbon invested in reproduction, pollinator attraction and feeding represented only 0.08-0.12% and 1.84-2.33%, respectively, while pollinator sheltering (fig construction and respiration) represented 97.6-98.0%. In this strict and coevolved plant-pollinator association, the main male reproductive investment was thus in the structures sheltering the associated pollinators.