Mineralization processes in some samples from the fossil forest of Dunarobba (Umbria, Central Italy)

 Two isolated twigs (samples A and B) from the site of the fossil forest of Dunarobba (Central Italy) were examined to assess both the degree of degradation of the organic fraction and the composition of the inorganic component. Sample A, although showing the presence of minute crystals, is mineralised only to little larger extent with respect to the trunks of the fossil forest and exhibits a wood composition almost comparable to that of the fossil forest. Main minerals are silica, calcite, chloroapatite, chloromagnesite, and clays. Residual terpenes perfectly match, as either components or proportions, those found in the fossil forest trunks. Sample B is much more mineralised and physical parts are hard (sample BII, 84% mineralisation) along with others that are quite loose (sample BI, 62% mineralisation). Goethite constitutes the major mineral in both parts. Calcite, on the contrary, is higher in BII than in BI. In agreement with the literature, goethite is present in the interstitial spaces of the cell walls whereas calcite is found in the cell lumina. The wood components are limited to lignin and terpenes; being absent cellulose or other polysaccharides. BI contains the same types of terpenes present in the fossil trunks, whereas only diterpenes have been found in BII. The samples B contain, with respect to either sample A or fossil trunks, a lower content of fully or partly aromatic sesquiterpenes and diterpenes. This fact is probably due to the oxidative environment of iron deposition. The difference in the mineralogical structures exhibited by the two samples must be searched in the different environmental conditions under which the samples were maintained. In particular, an essential role must have been played by water sources much richer in soluble salts and more differentiated than the current spring waters of the region. Received 6 March 1999     

From lethality to mortality: exploring the “grey area” of knockdown as an efficacy indicator of different insecticides against major storage insects using a lethality index

In the present work, a lethality index was applied for the evaluation of three insecticides with different modes of action, i.e., thiamethoxam, chlorfenapyr and lambda-cyhalothrin, as surface treatment against adults of Sitophilus oryzae (L.), Oryzaephilus surinamensis (L.) and Tribolium confusum Jacquelin du Val, in laboratory bioassays. The insecticides were applied at their highest label dose, while insect knockdown and mortality were evaluated after 1, 3, 5 and 7 days of exposure to the treated surfaces according to the Standardized Lethality Index, by ranking each insect from “0” to “4,” with “0” corresponding to insects moving normally and “4” corresponding to dead individuals. After the end of the exposure, the surviving insects were transferred to clean, untreated dishes and delayed mortality was assessed after an additional period of 1, 3, 5 and 7 days. Based on the results, initial knockdown was high for S. oryzae after exposure to thiamethoxam and lambda-cyhalothrin even after 1 day of exposure, whereas for longer exposures high mortality levels were recorded. In contrast, in the case of chlorfenapyr knockdown was low after 1 day of exposure; however, high mortality levels were noted after 3 and 5 days of exposure. Similar results were noted for O. surinamensis, which was highly susceptible to all three insecticides tested. The most tolerant insect species to the tested insecticides was T. confusum, since a noticeable number of T. confusum adults were still active at the end of the exposure (7 days). Our results indicate that knockdown is most likely to lead to mortality than to recovery, but there were important differences among the three insecticides tested.     

板栗兴透翅蛾的初步研究

板栗(Castanea mollissima)是河北省的主要经济树种，近年来，受到板栗兴透翅蛾(Synanthedon castanevora Yang et Wang)的严重危害，造成栗实减产，甚至树木死亡。     

异尾华枝虫生物学特性及防治

异尾华枝 虫 Sinophasma mirabile Günther在华东地区是一种新发现的危害壳斗科树木的重要食叶害虫。在浙江泰顺 1年发生 1代 ,以卵越冬 ,若虫和成虫大量取食寄主树叶造成树木生长衰弱甚至枯死。该文介绍了该虫的年生活史、发育过程、生活习性、取食量、天敌种类和防治方法 ,采用燃放烟剂、树干注药、地面喷药等措施 ,防治效果显著     

N concentration of old leaves and twigs is more sensitive to stand density than that of young ones in Chinese fir plantations: a case study in subtropical China

Young leaves are conventionally used in the analysis to study the nutrient status of evergreen plants and their responses to environmental changes, but the role of old leaves remains poorly understood. We selected two stand types in 31-year-old Chinese fir (Cunninghamia lanceolata) plantations with similar soil conditions but different stand densities, to test the hypothesis that nitrogen (N) concentration of old leaves and twigs is more sensitive to stand density than that of young ones. Leaves and twigs were sampled and sorted into young (one-year-old) and old (two- and three-year-old) groups. Significant differences in N concentration and carbon: nitrogen ratio between the low-density stand and high-density stand were only found in the old leaves and twigs but not in the young ones. Although the N resorption efficiency did not vary significantly with stand density, the annual N resorption rates were increased in old leaves and relatively young twigs at high stand density. These results show the potential use of old tissues in the nutrient analysis in Chinese fir plantations. Testing the generality of these results could improve the use of foliar analysis as an indicator of nutrient status and environmental changes in evergreen tree species.     

Temporal variations in endophytic fungal assemblages of Ginkgo biloba L.

We isolated endophytic fungi from living healthy leaves, petioles, and current-year twigs of Ginkgo biloba L. from April to November 2004 with the objective of identifying the dominant endophytic fungal taxa, and monitoring their occurrence and frequency. A total of 9 fungal taxa were identified to the genus level. Diversity measures inferred from the Shannon–Wiener, Morisita–Horn, and S?rensen indices indicated that leaves and petioles harbored more diverse endophytic fungal assemblages than twigs, and that fungal taxa involved in twigs shared less with those in leaves and petioles. Among the organs, the occurrence pattern of overall endophytic fungi differed significantly, and two taxa, Phomopsis sp. and Phyllosticta sp., were the most frequently isolated and thus regarded as the dominant endophytic fungi. Phomopsis sp. was isolated frequently from twigs (84.8%) but rather few from leaves (16.1%) and petioles (24.3%). Phyllosticta sp. was isolated frequently from leaves (72.9%) and petioles (65.7%) but was never isolated from twigs. Temporal changes in relative frequency of total endophytic fungi tended to differ among sampling dates for all three organs. The occurrence of Phyllosticta sp. in both leaves and petioles was first detected in August and peaked in October. Phomopsis sp. was detected in twigs throughout the growing season. These results suggest that the distribution of the two dominant endophytic fungi was organ-specific and differed within seasons.     

无患子单芽低位嫁接技术研究

对无患子进行了单芽嫁接技术试验。结果表明:不同季节和嫁接方法对无患子的嫁接成活率、抽梢率和抽梢长度的影响极为显著。以春季采用片芽腹接技术嫁接的平均成活率、抽梢率、抽梢长度最高,分别为98.3%,96.7%和64.4cm。     

Differences in composition of endophytic mycobiota in twigs and leaves of healthy and declining Quercus species in Italy

The composition of the endophytic fungal assemblages in Quercus cerris, Q. pubescens and Q. robur, three oak species most susceptible to decline, was investigated in Fagarè (Padova), Ulignano (Pisa), and Radda in Chianti (Firenze). The endophytic assemblages were studied as a function of health status of the whole tree and of twigs and leaves. The effect of station altitude was tested on Q. cerris. Samples were gathered from healthy and declining trees. In April (bud opening time) 20 twigs and 10 leaves were collected from each tree. Fungi were isolated from twig segments and leaf portions. A total of 23 fungal genera with 27 different species were isolated, in addition to a few sterile mycelia. Eleven species were found to be common to all three oak species, while other species were found only on one oak species, suggesting host specificity. Among the fungal species isolated, some were known to be pathogenic (Apiognomonia quercina, Colpoma quercinum, Diplodia mutila, Phomopsis quercina). The colonization frequency (CF) of pathogenic species varied between 0.9% for A. quercina in Q. cerris and 60.2% for P. quercina in Q. robur. Analysis of variance showed a statistically significant difference among the oak species tested. The CF was higher in declining trees in comparison with healthy trees, and also in twigs vs. leaves. The CF was found to be higher for Q. cerris trees growing at sea level as compared with those situated at an elevation of 350–400 m. In stands where, on account of particular ecological conditions, pathogenic behaviour is displayed simultaneously by more than one endophytic fungal species, trees accentuate their decline.     

5种植物源杀虫剂对淡竹毒蛾幼虫的毒力及林间防治效果

为筛选出有效控制淡竹毒蛾幼虫的药剂,以制定无公害防治淡竹毒蛾决策,2017年在福建省沙县选用5种植物源杀虫剂,对危害方竹林的淡竹毒蛾幼虫进行室内毒力测定和开展林间防治试验。室内毒力测定结果表明：1%苦皮藤素可溶液、4%鱼藤酮乳油、0.5%藜芦碱可溶性液、1.2%烟碱·苦参碱可溶液、1.5%苦参碱可溶液对淡竹毒蛾幼虫的LC₅₀分别为0.973、1.062、1.216、0.482、0.836 mg/L,以1.2%烟碱·苦参碱可溶液剂对淡竹毒蛾幼虫毒性最强,5种不同植物源杀虫剂对淡竹毒蛾幼虫均有杀虫作用。林间防治效果表明：药后3 d,5种植物源杀虫剂的防治效果均为90%以上,以苦参碱类药剂防治效果最好,2种苦参碱类药剂的林间最佳使用浓度均为1 500倍液;1%苦皮藤素可溶液和0.5%藜芦碱可溶性液林间最佳使用浓度为1 000倍液;4%鱼藤酮乳油林间防治最佳使用浓度为1 200倍液。测试的5种不同植物源杀虫剂均对淡竹毒蛾幼虫有良好的杀虫作用,是无公害防治淡竹毒蛾幼虫的有效药剂。