Wichtige,in Hokkaido (Japan) durch schädliche Forstinsekten verursachte Probleme

Ohne ZusammenfassungHerr Dr. Motonori Inouye ist der Chef-Forstentomologe der japanischen forstlichen Versuchsanstalt von Hokkaido. Mit dieser Veröffentlichung beginnt eine in zwangloser Folge erscheinende Reibe von Arbeiten, in der über Schädlingsfragen in verschiedenen Ländern berichtet wird. Die Schriftleitung.     

Fog and Precipitation Chemistry at Mt. Rokko in Kobe, April 1997-March 1998

Fog water and precipitation were collected and analyzed to study fog and precipitation chemistry. The research was carried out through one year from April 1997 to March 1998 at Mt. Rokko in Kobe. Higher fog occurrence and larger volume of fog water were observed in summer, corresponding to the trend of seasonal variation in precipitation amount. The annual mean pH value of fog water (3.80) was lower by ca. one pH unit than that of precipitation (4.74). The concentration of chemical species in fog water was ca. 7 times that in precipitation. The highest anion and cation concentrations were SO₄ ^2? and NH₄ ⁺ in fog water and Cl^? and Na⁺ in precipitation, although the Cl^?/Na⁺ equivalent ratio in both fog water and precipitation was almost the same value as that in sea water. It is considered that in the longest fog event, NH₄ ⁺ and nss-SO₄ ^2? in fog water mainly scavenged as (NH₄)₂SO₄, mainly derived from (NH₄)₂SO₄ (aerosol) in the atmosphere, NH₃ was scavenged at the growing stage, and SO₂ was also scavenged after the mature stage. NO₃ ^? in this fog event was mainly absorbed as HNO₃.     

Die Einschleppung des Amerikanischen Webebären (Hyphantria cunea Drury) in Japan nach dem 2. Weltkrieg

Schlußfolgerungen Eine Vermehrung kann mehrere Jahre in Tokyo stattgefunden haben, ohne daß sie die Aufmerksamkeit erregt hätte und kann dann plötzlich stark in Erscheinung getreten sein. Obwohl dieser Schädling gegenwärtig in Tokyo im Vergleich zum Beginn seiner Massenvermehrung infolge der natürlichen Feinde und der künstlichen Bekämpfung nicht bedeutend ist, so muß in der Zukunft, wie oben erwähnter Autor betont, eine weitausgedehnte Kontrolle fortgesetzt werden.Zum Glück ist diese eingeschleppte Art, die sich in Japan festgesetzt hat, gegenwärtig für die Forstwirtschaft von geringer Bedeutung.     

Characteristics in Concentration of Chemical Species in Ambient Air Based on Three-Year Monitoring by Filter Pack Method

Continuous monitoring of concentrations of particulate matter and gaseous compounds for three years by a four-stage filter-pack method clarified the characteristics in the concentrations of chemical species in particulate matter and gaseous compounds in ambient air in Kobe, Japan. The amount of materials in blank filters was low enough for this method to be used for the monitoring of ambient air. Little or none of the hydrogen chloride was derived anthropogenically. The concentrations of both particulate sulfate and sulfur dioxide in spring and summer were significantly higher than those in autumn and winter. The concentration of gaseous nitric acid was high in summer, which suggests that active photochemical reactions in the atmosphere provided more nitrogen species in summer. The measured concentration products [HNO₃][NH₃] showed good agreement with the theoretical predictions with some exceptions. The total concentration of ammonium species showed no significant seasonal variation except that the concentration in winter was low. The concentration of nss-Ca²⁺ in spring was significantly higher than that in the other seasons, which is most likely associated with the so-called yellow-sand events. The concentrations of nss-K⁺ and nss-Ca²⁺ accounted for most of K⁺ and Ca²⁺, respectively, whereas that of nss-Mg²⁺ accounted for only 5% of Mg²⁺     

Production of asexual and sexual offspring in the triploid sexual planarian Dugesia ryukyuensis

Certain freshwater planarians reproduce asexually as well as sexually, and their chromosomal ploidies include polyploidy, aneuploidy and mixoploidy. Previously, we successfully performed an experiment in which a clonal population produced by asexual reproduction of the Dugesia ryukyuensis (OH strain) switched to the sexual mode of reproduction. Worms of this strain are triploid with a pericentric inversion on Chromosome 4. The worms were switched to sexual reproduction after being fed with sexually mature Bdellocephala brunnea, which is a sexually reproducing species. The resulting sexualized OH strain produced cocoons filled with several eggs. Two putative factors, Mendelian factor(s) and chromosomal control(s), have been proposed as determining the reproductive mode. The present study demonstrated that inbreeding of the resultant sexualized worms produced the following four types of offspring through sexual reproduction: diploid asexual worms, triploid asexual worms, diploid sexual worms and triploid sexual worms. The chromosomal mutation on Chromosome 4 was inherited by these offspring independent of their reproductive mode. These results provide two important pieces of information: (i) the putative genetic factor was not necessarily inherited in a Mendelian fashion; and (ii) the reproductive mode is not regulated by chromosomal changes such as polyploidy or chromosomal mutations. This suggests that asexuality in D. ryukyuensis is regulated by an unknown factor(s) other than a Mendelian factor or a chromosomal control.     

Nocturnal isoprene emission from mature trees and diurnal acceleration of isoprene oxidation rates near Quercus serrata Thunb. leaves

Quercus serrata Thunb. ex Murray is a widespread deciduous oak in China, the Korean Peninsula, and Japan, and a strong isoprene emitter. Establishing accurate inventories of this species and estimating net carbon budgets, including biogenic volatile organic compounds (BVOC), necessitates detailed evaluation of BVOC emission and oxidation characteristics. Emissions of isoprene, the most abundant BVOC, presumably contribute to atmospheric chemistry through the formation of photochemical oxidants and secondary organic aerosols. We built an isoprene flux monitoring system to simultaneously reveal characteristics of the flux and fate of isoprene at multiple locations in Q. serrata forests. We used proton transfer reaction mass spectrometry (PTR-MS) and an automated closed chamber to measure isoprene emissions from soil and leaves in a warm-temperate Q. serrata forest. We used a relaxed eddy accumulation system with PTR-MS to simultaneously measure the canopy flux. In continuous foliage chamber measurements, we observed daily variations of isoprene emissions and continuous nocturnal emissions from leaves. Nocturnal emissions exceeded 25 % of total daily leaf emissions and were relatively high at sunset and low at sunrise. These results suggest that nocturnal emissions from mature trees may not be negligible. When leaf emissions were high in the daytime, the canopy isoprene flux tended to plateau at an upper limit. Observations of isoprene concentrations and gradients suggest that the plateau was caused by acceleration of isoprene oxidation, and sequential formation of secondary organic aerosols may occur near the leaf just after emission. Elucidation of these linkages may require continuous field measurements with a simultaneous multi-flux monitoring system.     

Importance of basic cultivation techniques to increase irrigated rice yields in Tanzania

The productivity of irrigated rice is low in Tanzania. We hypothesized that this is caused by the absence of a packaged application of basic cultivation techniques. A baseline survey of 31 rice irrigation schemes across the country revealed that a large proportion of fields were cultivated without a technical package. Thus, a package was introduced to each of the 31 schemes through a farmer-to-farmer (FTF) extension approach. First, selected key farmers (KFs) were trained with the basic cultivation techniques at agricultural training institutes. Second, the KFs transferred their knowledge to intermediate farmers (IFs) by working together at a demo-field established in each scheme. Third, the KFs and IFs exhibited the rice performance to other farmers (OFs). The paddy yield across the 31 schemes greatly increased from the pre-training level of 2.4 t ha^?1 to 3.6 t ha^?1after the FTF extension. However, the farmer interviews in the four selected schemes suggested that the technical package was not adopted by all farmers owing to the time-consuming nature of the FTF extension. It was inferred from our study that the low productivity of irrigated rice is caused by the absence of basic cultivation techniques in Tanzania. However, the post-training yield remained relatively low compared with high-yields (4.3–8.4 t ha^?1) recorded in cultivar selection trials and high-performing schemes in the county. This “yield gap” could be partly ascribed to the insufficient technical diffusion and the technique-dependent adoption among OFs.     

Intensive Field Survey of Aerosol and Gas Concentrations with 6-h Interval Sampling in Winter in Japan

We intensively surveyed the concentrations of chemical species in aerosols and gases using a four-stage filter-pack method at a site in Japan facing the Sea of Japan in winter with 6-h sample intervals. A few chloride species emitted anthropogenically were detected, and the HCl (g) concentration was quite low. The number of chloride species artifacts was also low. The HNO₃ (g) concentration was significantly higher when the monitored air mass passed over the Korean Peninsula compared to when it did not pass over the Korean Peninsula. In addition, the HNO₃ (g) concentration was significantly higher when the air mass arrived at the monitoring site by passing the route at lower latitude than the latitude of the monitoring site. On the other hand, the SO₂ (g) concentration showed no change between various trajectories of the air mass. The $ {\text{NH}}^{ + }_{4} $ (p)/non-seasalt- (nss-) $ {\text{SO}}^{{2 - }}_{4} $ (p) ratio was intermediate between the compositions of (NH₄)₂SO₄ and NH₄HSO₄ when the air mass passed over the Korean Peninsula, whereas it was intermediate between NH₄HSO₄ and H₂SO₄ when the air mass did not pass over the Korean Peninsula. We detected the transboundary transport of sulfur dioxide with high time-resolution monitoring at two separate monitoring points: the current monitoring site and Oki Island.