松突圆蚧危害时间与危害程度关系的初步探讨

马尾松林受松突圆蚧危害的轻重与危害时间的长短有密切的关系。试验结果表明:松突圆蚧侵害的时间越长,马尾松受害程度也越严重。根据这两者的关系,可以预测马尾松林遭松突圆蚧危害后的发展趋势,在生产上有一定的实用意义。     

调整松林密度控制清源山松突圆蚧危害的试验

通过对发生区内松林进行间伐、修枝等营林措施将郁闭度调整至0 5左右,松林中松突圆蚧的虫口密度从调整松林密度前的每束2 61头下降至0 63头,虫口密度下降75 86%,表明调整松林密度能有效地控制松突圆蚧对松林的危害;同时发现,阳坡上松林的虫口密度较阴坡上松林的虫口密度大,从阳坡向阴坡逐步过渡,松突圆蚧的虫口密度也随之下降,表明松突圆蚧的虫口密度与坡向有关,在景区绿化规划设计上应针对不同的坡向营造不同的树种,以防止松突圆蚧的发生和危害。     

西江林业局直属林场松突圆蚧危害调查

连续3年对广东省西江林业局直属9个林场的马尾松林分设立标准地进行松突圆蚧的虫情调查,同时调查胸径生长情况。结果表明：被调查标准地所在的高要、德庆、云城、新兴、云安、郁南等区县均为松突圆蚧发生区;各标准地因受害时间及危害程度不同,造成虫口密度有极显著差异;不同龄组的马尾松均受到松突圆蚧的危害,同一时期,林龄越大,虫口密度越大;除通门林场外,其他各标准地由于受到松突圆蚧的危害,森林资源增长缓慢。建议将西江林业局受松突圆蚧危害的马尾松林纳入广东省林分改造工程建设范畴,间伐或皆伐后套种或全面更新阔叶树种,从根本上遏制松突圆蚧的虫情升级和蔓延。     

松突圆蚧危害与森林植被特征关系的调查研究

本文从马尾松林植被特征这一生态因子分析了它与受松突圆蚧危害程度的关系,结果表明森林植被类型(以群丛为单位)的不同可以反映出林分的被危害类型;而林分郁闭度在0.5～0.65时,马尾松林受危害程度最轻,说明合理调整林分郁闭度是控制松突圆蚧危害的重要措施之一。     

广东松突圆蚧发生类型区分析及防控对策

松突圆蚧是一种危害松林的外来有害生物.为寻求以生物防治为主的综合治理措施,分析了广东松突圆蚧发生类型区,分别介绍了松突圆蚧低虫口分布区、不稳定区、严重危害区3种发生类型区的分析情况,同时提出发挥本地寄生天敌对松突圆蚧的防控作用,并进一步探讨利用花角蚜小蜂的有效途径等综合治理对策.     

松突圆蚧生物学特性的研究

松突圆蚧(HemiberlesiapitysophilaTakagi)是松类的重要检疫性害虫。文中以福建某试验地松林为研究点,对松突圆蚧的生物学特性进行了系统观察研究。4～7月份是虫口密度最大、危害最严重的时期。松突圆蚧有完整的生活周期即有有性世代,每雌平均产卵量为93粒,林间自然雌雄性比为2 05∶1。1a发生4代,世代重叠。     

广东省松突圆蚧发生区划研究

依照松突圆蚧Hemiberlesia pitysophila Takagi的灾害特点,将广东省松突圆蚧发生区以县级为单位进行了发生区划,并构建了基于气象因子的灾害程度判别模型,依据该模型结合林分构成和林业经营特点研究了松突圆蚧发生区划,将广东省松突圆蚧发生区划分为轻度分布、中度发生和重度危害3个区域,并提出了各区域松突圆蚧防治策略.     

松突圆蚧种群数量的调查与分析

松突圆蚧(Hemiberlesia pitysophila Takagi)自1982年5月首次在我国珠海市毗邻的马尾松林内被发现以来,到1988年,危害面积已超过650万亩。由于马尾松林所处生态环境的差异,表现了受害程度的不同,对这些危害类型不同的林地,我们在惠东、新会、博罗、中山、深圳、珠海6县(市)设置标准地,对虫口数量、天敌、气象、土壤、植被和林分结构等进行了多学科的调查研究。现把松突圆蚧在不同危害类型和郁闭度中的种群数量整理如下。     

浙江省松突圆蚧入侵风险分析

根据松突圆蚧的生物学特性、分布状况、潜在风险性和奇主经济重要性等,对浙江省松突圆蚧入侵风险进行了分析评估,结果表明,浙江省为松突圆蚧生态适生区和易爆发流行区,松突圆蚧入侵风险值达2.092 4,为高度危险的外来林业有害生物,并提出了加强检疫和进行松林林相改造的营林措施来有效减少入侵风险.     

触目惊心的“洋害虫”

洋害虫危害不浅 自去年秋季以来,广东旅游名城肇庆市的“市肺”──北岭山松林遭到梢枯病、松突圆蚧、松墨天牛等病虫害袭击,６０年代造起的美丽生态风景林木大面积枯死。松突圆蚧是一种突发性强、传播迅速的虫害,由风、带虫树种和木材等途径传播．主要危害马尾松。松林遭松突圆蚧入侵后并发梢枯病,使树木枯黄致死。现今国内外还没找到有效遏制该虫害的办法。此虫害于１９８２年由海外经港澳传入珠海逐步蔓延到广州．佛山,江门等市．肇庆市北岭山于１９９７年开始发现松突圆蚧入侵林业部门曾采取施放虫害天敌花角蚜小蜂和清理病树等办…     

双江县华山松球蚜发生数量研究

华山松球蚜以成虫和若虫群集在华山松嫩枝，梢，针叶上吸食汁液。温度和湿度对华山松球蚜的发生影响较大；相对湿度在58%-70%，危害严重，相对湿度在75%以上时，华山松球蚜数量减少；5月为发生危害高峰期。     

Vascular tissue anatomy of Norway spruce needles and twigs in relation to magnesium deficiency

Vascular tissues of needles and twigs of Norway spruce with low foliar magnesium concentrations were examined by light microscopy. Observations were made on samples from (1) apparently healthy trees, (2) trees exhibiting progressive symptoms of decline, including the yellowing and fall of needles and the death of twigs and branches in the subapical canopy, and (3) trees recovering from symptoms of decline after fertilization with magnesium sulfate. Abnormalities in cambium and phloem anatomy, which were apparent in 2-year-old needles of declining trees, were seen only in needles at least 4 years old in healthy trees, suggesting that needles of declining trees are susceptible to precocious aging. Abnormalities in xylem anatomy were observed in needles 3 years or more in age in declining trees, but were never seen in needles of healthy trees. Over time, anatomical abnormalities in declining trees were seen in progressively younger twigs, which may explain the acropetal development of decline symptoms. After fertilization with magnesium sulfate, normal phloem and xylem were observed in the newly formed tissues.     

Seasonal differences in freezing stress resistance of needles of Pinus nigra and Pinus resinosa: evaluation of the electrolyte leakage method

Seasonal changes in freezing stress resistance of needles of red pine (Pinus resinosa Ait.) and Austrian pine (Pinus nigra Arnold) trees were measured by an electrolyte leakage method and by visual observation. During most of the year, freezing stress resistance determined by the two methods gave similar results. The electrolyte leakage method provided a good estimate of seasonal changes in freezing stress resistance except for red pine needles in their most winter-hardy state. To obtain a reliable estimate of freezing stress resistance in winter-hardy red pine needles it was necessary to combine the electrolyte leakage method with visual observations. When red pine needles survived exposure to -80 degrees C or lower, electrolyte leakage was never more than 30% even when the needles were exposed to a slow freeze-thaw stress of -196 degrees C. However, rapid freezing of red pine needles to -196 degrees C resulted in electrolyte leakage of over 80%. Red pine needles attained a much higher freezing stress resistance during the winter than Austrian pine. Red pine needles also acclimated and deacclimated faster than Austrian pine needles. An index of injury was developed based on the electrolyte leakage method ((R(2) + R(1))/2, where R(1) is the minimum % electrolyte leakage from noninjured tissue and R(2) is the maximum % electrolyte leakage at the highest injury) that reliably predicted freezing stress resistance of pine needles for most of the year. Important aspects for developing a successful index of injury for pine needles are: use of cut needles, vacuum infiltration and shaking during incubation in water.We conclude that: (1) during cold acclimation the cell wall properties of the pine needles changed and these changes, which appeared to differ in the two species, might explain the very low leakage of electrolytes from winter-hardy needles of red pine; (2) pine needles survive winter by developing the ability to tolerate extracellular ice formation, because after rapid freezing the needles were severely injured; and (3) red pine is adapted to a shorter growing season and colder winters than Austrian pine.     

Within-tree distribution and attractant sampling of propagative pinewood nematode, Bursaphelenchus xylophilus: An early diagnosis approach

Early detection is of primary importance to enable rapid actions to prevent the spread and introduction of invasive species. The pinewood nematode (PWN), Bursaphelenchus xylophilus, a serious invasive and destructive species, is listed as a quarantine pest in the legislation of more than 40 countries. However, Baermann funnel extractions of wood from discs cut from trees at breast-height often do not detect the presence of PWN in infested trees. A serious consequence of such false negatives is the loss of the best window for implementation of eradication or quarantine measures to prevent establishment of incipient PWN infestations. Here we document the within-tree horizontal and vertical distribution of PWN in infested stands in China, using a newly developed kairomonal trapping technique. Our results provide a simple, effective, rapid and non-destructive sampling method that takes into account the changes of PWN within-tree distribution in relation to pine wilt disease (PWD) symptom development. When 60–80% of the foliage has become pale green, PWN is recovered from larger diameter branches. As disease symptoms progress, PWN moves into and down the trunk. As the needles turn yellow, PWN was recovered from the trunk at 1–2 m above the ground. The correlation between the within-tree distribution of PWN and the expression of symptoms indicated a strong association between the distribution of PWN and physiological and pathological changes that develop in attacked pines through the interaction between PWN and tree. This systematic sampling technique takes into account the within-tree distribution of the nematode and should greatly enhance early detection of PWN in field surveys, monitoring and phytosanitary inspections.     

果梢斑螟对马尾松球果和雄花序枝生长发育的影响

果梢斑螟Dioryctria pryeri Ragonot是我国马尾松雄花、球果和枝梢的重要钻蛀性害虫。幼虫钻蛀主梢,引起枯萎,树干弯曲,影响高生长和材质;钻蛀雄花枝,引起雄花枯萎,影响雌花受粉,雄花枝遭蛀大量折断后,枝基当年萌芽,形成众多的细枝,钻蛀球果,引起萎蔫、落果,造成马尾松种子园种子产量严重歉收。果梢斑螟在浙江省一年一代,以幼虫越冬。翌年3月上旬至5月中旬,是马尾松雄花含苞、开放和二年生球果逐渐膨大时期,果梢斑螟越冬幼虫随即蛀入雄花序枝和球果,但有关该虫对马尾松球果、雄花序枝生长发育的影响迄今未见报道。本文旨在探索果梢斑螟危害对马尾松增枝、枝的生长量等的关系,为确定该虫的防治指标的研究提供参考依据。     

利用引诱剂和肿腿蜂防治松墨天牛的研究*

松墨天牛是松树的主要蛀干害虫,亦是松材线虫病的主要传播媒介。利用引诱剂能够大量诱集松墨天牛,使用浓度以1:3较为经济实用。1号引诱剂诱虫能力最强,1、2号混合液及4号诱虫效果次之。诱虫量一般比对照提高17.8～54.9倍,比伐倒木提高1.2～3.2倍,比病虫枯死木提高5.8～7.2倍。诱集后可降低林木枯死率2％～32％,防治效果达70％～95％。施引诱剂的同时再施1:1的氧化乐果稀释液可毒杀62.4％～100％的天牛幼虫。每公顷释放管氏肿腿蜂28 142头,当代防治效果可达40％～50％,经3～4个月持续防治效果可达69.6％～85.3％。     

甘肃白水江林区落叶松球蚜红杉亚种发生及防治

落叶松球蚜红杉亚种以成虫和若虫群集在落叶松嫩枝、梢、针叶上吸食汁液。温度和湿度对红松球蚜的发生影响较大；相对湿度在58％-70％时，危害严重；相对湿度在75％以上时，落叶松球蚜数量减少；5月为发生危害高峰期。施药区相对防治效果可达92．4％。     

Feeding in the Crowns of Scots Pine Trees by the Pine Weevil Hylobius abietis

Hylobius abietis (L.) (Coleoptera:Curculionidae) is the major insect pest of forest regeneration in Europe, where adult weevils kill conifer seedlings by feeding on the bark. This study demonstrates that pine weevils also feed extensively in the crowns of mature coniferous trees. Crown feeding primarily took place during a limited period immediately after the migration to new breeding sites (roots of freshly cut coniferous trees). The weevils reached the crowns mainly by flight and tended to concentrate on trees in freshly cut-over areas. The proportion of sexually mature females successively increased during the crown-feeding period, indicating that they require a certain period of maturation feeding. The pine weevils fed on twigs of 3-20 mm thickness, and they consumed about 0.2-0.3% (200 cm²) of the total bark surface in the crowns of mature Scots pine trees. Calculations suggested that the amount of food consumed in the trees surrounding a fresh clear-cutting should have met the nutrient requirements of the weevil population in the area during the maturation feeding period. In the crowns of shelterwood trees, about 50 cm² of the bark was consumed per tree (0.63 m² ha-1). This level of consumption is not believed to be high enough to relieve the feeding pressure on seedlings and thereby explain the low level of damage usually found under shelterwoods.