Frost Injury as a Possible Inciting Factor in Bud and Shoot Necroses of Fraxinus excelsior L.

Large numbers of European ash have died in Poland in all age classes during the last ten years. The characteristic symptom occurring on shoots of planted and self‐sown seedlings was bark necroses starting from the shoot apex, necrotic buds, or leaf and twig scars. The results showed that in the bud tissue of cold acclimated European ash extracellular and intracellular ice formation occurred at approximately ?9 and ?32°C, respectively. In deacclimated plants in spring water supercooling is limited by the heterogenous ice nucleation temperature and consequently the cold tolerance is ?9 to ?4°C for bud tissues and ?13 to ?9°C for shoots. Isolations of fungi were performed from dead buds and from necroses occurring on the main stem. Alternaria alternata, Fusarium lateritium and Phomopsis scobina were among the fungi occurring in both these organs at frequencies of more than 7%. Cylindrocarpon heteronemum, Diplodia mutila and Tubercularia vulgaris from necroses were only isolated in frequencies; 3.3, 1.2 and 5.4%, respectively. It seems likely that freezing injury is the inciting factor, which combined with fungal colonization manifests itself as fatal damage to European ash buds and shoots.     

Egg weight, batch size and fecundity of the spotted stalk borer, Chilo partellus in relation to weight of females and time of oviposition

The egg laying pattern of the spotted stalk borer on sorghum and maize, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) was studied during the first three nights of oviposition under laboratory conditions. More than 50% of both eggs and egg batches are laid during the first night of oviposition. Batch size decreases with time, whereas mean egg weight remains constant.Larger females lay both larger eggs and egg batches than smaller ones. They are also more fecund but it is only the second night of oviposition that contributes significantly to this difference.The reproductive effort decreases much with time. Allocation of reproductive reserves to early eggs seems more important than having eggs evenly distributed over time. Larger females use proportionally more resources to the production of late eggs. Large eggs are likely to contain more yolk which could be of importance for the ballooning behaviour of newly hatched larvae.

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Résumé La ponte de C. partellus Swinhoe a été étudiée au laboratoire pendant les trois premières nuits de la ponte. Plus de 50% des ooplaques et des oefs ont été pondus pendant la première nuit. La taille des ooplaques diminue avec le temps, tandis que le poids moyen des oeufs reste constant.Les grosses femelles pondent des ooplaques et des oeufs plus grands que les petites. Elles sont aussi plus fécondes, mais c'est seulement à la seconde nuit de ponte qu'est due cette différence.Le reproduction diminue beaucoup avec le temps. L'affectation aux premiers oeufs des réserves utilizées pour la reprodution semble plus importante que l'émission d'oeufs régulièrement répartis dans le temps. Les grosses femelles utilisent proportionnellement plus de ressources à la production d'oeufstardifs. Les gros oeufs contiennent vraisemblablement plus de vitellus que pourrait être nécessaire pour le comportement aérostatique des chenilles néonates.

     

Tylenchulus graminis n. sp. and T. palustris n. sp. (Tylenchulidae), from Native Flora of Florida,with Notes on T. semipenetrans and T. furcus

Tylenchulus graminis n. sp. and T. palustris n. sp. are described and illustrated from broomsedge (Andropogon virginicus L.) and pop ash (Fraxinus caroliniana Mill.), respectively. T. graminis resembles T. furcus in having a distinct anus, but T. graminis second-stage juveniles (J2) do not have a bifid tail. T. semipenetrans does not have a perceptible anus. The mature female of T. graminis has a mucronate pointed terminus while T. semipenetrans has a smooth and round terminus. T. graminis males have wider stylet knobs and basal bulb and a longer tail than T. semipenetrans males. T. graminis J2 have a longer posterior body portion (without large fat globules) than T. semipenetrans J2. T. palustris resembles T. semipenetrans in having an undetectable anus but differs by the short and conoid mature female postvulval section. The male of T. palustris has larger stylet knobs and basal bulb than those of T. semipenetrans and a bluntly rounded tail terminus, which is tapered in T. semipenetrans. T. palustris differs from T. furcus and T. graminis in having an undetectable anus, by the conoid postvulval section of mature females, by the shorter and rounded tail of males, and the shorter J2 posterior body section without large fat globules. T. graminis and T. palustris are parasites of indigenous flora of Florida.     

用杀虫双大粒剂防治水稻二化螟和三化螟的研究

本文报告一种防治水稻螟虫的杀虫双新剂型和使用效果.含有效成份5%的杀虫双大粒剂,每公斤含2000粒左右,在每亩1—1.25公斤的用量下,药效显著优于六六六、呋喃丹及杀虫脒等残留和高毒性农药.处理一亩田只需数分钟.在七个县和四个农场共266440亩稻田的示范试验中,防治效果达84.5—100%.杀虫双在田水中扩散迅速,24小时内即可扩散分布到全田.持效期较长,可达两周之久.但在蝗虫已蛀入稻茎后施用大粒剂,有效施药期只有3—4天.本文对杀虫双大粒剂的使用技术进行了经济效益、社会效益和生态效益方面的评价.     

梳角窃蠹的生物学与防治(鞘翅目:窃蠢科)

梳角窃蠹(Ptilinus fuscus Geoffroy)在青海省东部对杨树房木的蛀损最高达78.43%,平均为36.67%;房屋平均蛀危年限为20.46±9.42年.青杨干材的抗弯强度(kg/cm²)与其表面的蛀孔量(孔/200cm²)呈幂函数曲线相关:Y=559.9X^-0.2042.本种窃蠹2年1代.成虫主要发生于6月中、下旬至7月上、中旬;海拔每升高100米,发生期约推迟3.6天左右.成虫发生期喷洒80%敌敌畏200—400倍液4—5次,毒杀成虫有效.管氏肿腿蜂(Scleroderma guani Xiao和Wu)对潜藏在干材深层的窃蠹幼虫和蛹,有较高的寄生力.     

The fate of immunoglobulin G fed to larvae of Ostrinia nubilalis

Since plants can be transformed genetically to produce functional antibodies, an immunological approach may be developed for controlling their arthropod pests. Specific antibodies would protect plants from arthropods if they could gain access to the pest antigen in sufficient amounts such that the normal function of the antigen is disrupted. In order to study the fate of ingested antibodies in the body of the European corn borer (ECB), Ostrinia nubilalis (Hübner), (Lepidoptera: Pyralidae), we fed the larvae on serum-containing diet. When larvae were fed on the serum-containing diet for various lengths of time between 12 and 96 h, no significant differences were noted in the immunoglobulin G (IgG) concentration in their body. Immediately after the larvae stopped feeding, the concentrations of the IgG in their midgut was about one half that of the diet itself, but it decreased significantly after 6 h and again after 18 h (about 3 and 10 fold, respectively). Immediately after the larvae stopped feeding, the concentration of the IgG in their hemolymph was about 1/500 that in the diet. The concentration of IgG in the hemolymph of ECB larvae was influenced directly by the titer of antibodies in their diet. During the first 6 h after the larvae stop feeding the concentration of IgG in their hemolymph did not decrease significantly; however, it did so after 18 h (about 6 fold). The possibility that specific antibodies will gain access to antigens in the ECB body is discussed.     

谷蠹生态学特性的研究

谷蠹Rhyzoperthadominica（F．）生态学特性的试验结果表明,温度、湿度、粮食含水量对其各发育历期影响非常显著;食物影响不显著。     

Micropropagation of Frazinus angustifolia from mature and juvenile plant material

Micropropagation of Fraxinus angustifolia Vahl has been successfully achieved both from mature and juvenile plant material using shoot tip and nodal explants. Several basal media supplemented with benzyladenine (BA) and indolebutyric acid (IBA) were tested for shoot proliferation. The most new explants per mature explant (5.3) was obtained on DKW medium plus 4.4 M BA+0.98 M IBA. The most new explants per juvenile explant (5.6) was produced on QL medium plus 8.9 M BA+0.49 M IBA. Rooting was achieved on WPM supplemented with 0.98–4.9 M IBA. Rooted plantlets were transferred to soil and acclimatized with 85% survival.Abbreviations BA benzyladenine - IBA indolebutyric acid - NAA 1-naphthaleneacetic acid     

Nutrient fluxes in the shifting cultivation system of south-west Côte d'Ivoire

At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.