Variability in aggressiveness of Quambalaria pitereka isolates

Quambalaria shoot blight, caused by the fungal pathogen Quambalaria pitereka, is a serious disease of eucalypt plantations in Australia. The aggressiveness of four Q. pitereka isolates was compared on a range of host genera, species, provenances and clones. Isolates differed substantially in their aggressiveness, with two consistently showing higher levels of aggressiveness based on incidence and severity of disease and lesion size. Isolates derived from Corymbia citriodora subsp. variegata (Ccv) and C. torelliana were shown to have a relatively restricted host range, with lesions but no sporulation found on Eucalyptus species, Angophora species other than A. costata and Corymbia species other than Ccv, the host of origin. The level of aggressiveness toward the different provenances of spotted gum and C. torelliana varied between isolates and there was evidence of some isolate × host interaction within provenances of Ccv. The two methods of inoculation used in this study, spray and spot inoculation, gave similar results. However, the fact that the spot inoculation method was labour‐intensive was a disadvantage limiting the numbers of isolates and hosts that can be tested.     

Electrokinetic properties of variable charge clays in the presence of an anionic xanthan polysaccharide and inorganic electrolytes

The effect of the electrolytes (MA: NaCl, MgCl₂ , PbCl₂ , and NaH₂PO₄ ) on the polymeric (a) weak-stabilization (PWST), (b) flocculation (PFL); and (c) stabilization (PST) of allophane in the presence of xanthan polysaccharide (GX), was investigated by electrophoretic mobility (EPM) measurements. At pH 6.5 (i.e.p.), with further addition of chlorides, the decrease in the absolute value of the negative EPM (|—EPM|) of allophane in 0.01 mm MA solutions indicated the suppression of PWST and PST, respectively, probably due to the decrease in the repulsive force originating from the negatively charged GX-chains with the addition of MA. By first addition of MA, the decrease in the |—EPM| value of allophane in 0.01 mm NaCl and MgCl₂ solutions also showed the suppression of PWST and PST. In 0.01 mm PbCl₂ and NaH₂PO. solutions, the increase in the EPM and |—EPM| values of allophane reflected the dispersion due to the specific adsorption of Pb₂₊ and H₂PO₄ - ions on the negatively and positively charged sites of the surface, respectively. At pH 4.5, the decrease in the |—EPM| value of allophane in 0.1 mm NaH₂PO₄ solution indicated the suppression of PST due to the specific adsorption of H₂PO₄ - ion on the positively charged surface of the particles. The absence of (i) PWST in the presence of GX and (ii) high stability in the presence of cationic lead species for the flocculated imogolite at pH 8.5 can be attributed to the tubular structure proposed by Cradwick et al. (1972: Nature (London) Phys. Sci., 240, 187-189), namely, to the difficulty in the development of a negative charge on the outer surface of its unit particle.     

Effect of particle size of halloysite on the deflocculation of mutual flocs of allophane and halloysite at pH 6.5 in dilute xanthan polysaccharide solutions

The effect of the particle size of halloysite on the deflocculation of mutual floes of allophane and halloysite in the presence of anionic xanthan polysaccharide was investigated spectrophotometrically. Although allophane which flocculated at the i.e.p. (pH 6.5) exhibited polymeric (i) weak-stabilization (PWST), (li) flocculation (PFL), and (iii) stabilization (PST) with increasing addition of xanthan, allophane and halloysite which flocculated mutually at pH 6.5 inhibited the deflocculation, viz., PWST and PST. Halloysite with a smaller average particle size (i.e., 0.08,um in average diameter) than the suspended microaggregates (SMAs) of allophane inhibited significantly the deflocculation, suggesting that the halloysite particles flocculated around the allophane particles. Halloysite with a larger average particle size (i.e., 0.2 μn in average diameter) than the SMAs of allophane slightly inhibited the deflocculation, suggesting that the halloysite particles were attached to the center of the flocculated SMAs of allophane. The inhibitory effects of particle arrangements on the deflocculation of the mutual floes of allophane-montmorillonite and allophanekaolinite were also investigated comparatively.     

复凝聚法制备球孢白僵菌微胶囊

[目的]研究复凝聚法制备以明胶和阿拉伯胶为壁材的球孢白僵菌(Beauveria bassiana)微胶囊的工艺。[方法]通过单因素试验研究了明胶浓度、阿拉伯胶浓度、芯壁比、pH、反应温度和转速对微胶囊包埋效率的影响,再通过正交优化试验确定最佳制备条件;利用光学显微镜、扫描电子显微镜和粒径测微仪对球孢白僵菌微胶囊形态及粒径分布进行表征。[结果]复凝聚法制备球孢白僵菌微胶囊最佳工艺条件为明胶浓度1.5%、阿拉伯胶浓度0.5%、芯壁比1.0∶1.5、复凝聚反应pH 3.8、搅拌速度450 r/min,在该条件下可制得包埋率达78.32%、粒径分布均匀且平均粒径在44.16μm左右、流动性好的球型固体微胶囊。[结论]该研究制备的微胶囊符合实际应用需求,为真菌杀虫剂的研制提供了理论依据。     

Diversity,regeneration status and population structure of gum- and resin-bearing woody species in south Omo zone,southern Ethiopia

South Omo Administrative Zone in Ethiopia is home to 18 indigenous ethnic groups whose livelihood is vulnerable due to recurrent drought and degradation. Despite the preliminary observation showing the rich dry-forest resource base that, if sustainably managed could enhance livelihoods and biodiversity conservation, there is lack of empirical data on its current status. We conducted a study aiming at quantifying the population status of gum- and resin-bearing species in two randomly selected districts, Hamer and Bena-Tsemay. Seventy-five quadrats(35 at Hamer and 40 at Bena-Tsemay) each measuring 400 m2 were established along line transects to assess species diversity and equitability, density, frequency, dominance, importance value and population structure. We recorded a total of 27 woody species of 12 families and 14 genera. Fifteen species(9 at Hamer and 14 at Bena-Tsemay) of the genera Acacia, Boswellia, Commiphora and Sterculia, were identified as either major sources of commercial gums and resins or their adulterants. Gum- and resin-bearing species comprised 56% and 57% of species richness, 48% and 50% of total density per ha, 95% and 98% of basal area, and 64% and 56% of importance values at Hamer and Bena-Tsemay, respectively. Diversity of the entire woody species assemblage and of the gum- and resin-bearing species was slightly higher at Bena-Tsemay(H= 2.61, 1.4) than at Hamer(H′= 2.48, 1.28), respectively. The diversity and abundance of the resource base suggest potential for development of value-added commercialization of gum and resins to enhance livelihoods and encourage sustainable management of the forest at these study areas. We recorded, however, declining natural regeneration of most gum- and resin-bearing species, and this calls for integrated and participatory species management and landscape rehabilitation.     

Healed long-bone fractures in wild birds

AIM: To build a profi le of the oral lesions that occur in sheep in New Zealand that need to be considered within the differential diagnosis of foot-and-mouth disease.

METHODS: Lesions of the anterior lips and gums of sheep were surveyed in two abattoirs, photographed, and described grossly and histopathologically.

RESULTS: A sequence of lesions in order of age and stage of healing are described and illustrated, and their pathogenesis discussed. Lesions of the midline of the lips and gums of traumatic or irritant aetiology were common, and the prevalence was higher in adult sheep than in lambs.

CONCLUSIONS: The majority of lesions observed appeared to be primarily of traumatic aetiology. They probably arose from the fright/flight response behaviour of sheep, resulting in the mouth impacting against wire fences or yard railings while being handled. A smaller percentage of lesions may have been due to abrasive or irritant feed or soil. The presence of plant material and bacteria in lesions delayed healing and contributed to the formation of ulcers.     

昆虫病原线虫Steinernema carpocapsae A11品系叶面应用辅助剂的筛选

研究了12种物质对昆虫病原线虫Steinernema carpocapsae A11品系的抗干燥保护作用。这些物质在试验浓度下对线虫和小菜蛾3龄幼虫的存活以及对线虫的侵染率都无显著影响。线虫加入抗干燥剂后经滤纸干燥法处理和叶面喷洒试验结果都表明,甘油和黄原胶的抗干燥保护作用最好。     

添加胡麻胶后三唑酮沉积量和残留量的变化及其对小麦条锈病的防效

旨在研究添加胡麻胶后三唑酮沉积量和残留量的变化及其对小麦条锈病的防效。结果表明,胡麻胶具有提高三唑酮沉积量和残留量的作用,药后第3天残留量的提高幅度最大。w=15%三唑酮可湿性粉剂在900 g/hm剂量下,于900 L/hm药液中加入600 g/hm胡麻胶,沉积量为1.291 9 mg/kg,较不加胡麻胶提高24.86%;药后第3天的残留量为0.675 2 mg/kg,较不加胡麻胶提高111.99%。胡麻胶具有提高三唑酮对小麦条锈病防效的作用,施药后第7天的防效为87.34%,较不加胡麻胶提高8.23%。     

瓜尔胶降解菌诱变及甘露聚糖酶特性研究

为了筛选降解瓜尔胶的菌株,从亚麻液中筛选到l株降解瓜尔胶产β-甘露聚糖酶的细菌HL-28,经形态观察、生理生化特性和16S rDNA序列分析鉴定其为金黄杆菌（Chryseobacteriu）.菌株HL-28产甘露聚糖酶的活力达64.532 U/ml,经紫外诱变育种获得突变株HL-28-30,酶活提高到339.787 U/ml,提高了426.54％.粗酶发挥催化作用的最适pH值为5.6,最适反应温度50℃.     

Multi-scale site and landscape effects on the vulnerable superb parrot of south-eastern Australia during the breeding season

The threatened superb parrot of south-eastern Australia exemplifies many of the challenges associated with research on wide-raging organisms which live ‘off-reserve’. Challenges include that most land is privately owned and that landscape use by such organisms does not always conform to traditional schematic and categorical landscape/fragmentation models. A multi-scale approach for embedding the detection of site-level and landscape context effects into landscape sampling design and subsequent statistical analysis is presented. The superb parrot was found scattered at varying densities throughout the agricultural landscapes of the South-West Slopes, much of which was privately owned. It responded to site-level variables and the surrounding landscape context. Overall, the superb parrot favoured lower elevation sites which were dominated by scattered, open woodlands, where Blakely’s red gum was a significant component. Mean plant productivity within 2 km, levels of woody tree cover within 3 km and (with caveats) length of roads within 3 km had a major effect on site-level response, indicating conditions in the surrounding local landscape are important to the superb parrot. This multi-scale response requires a multi-scale conservation and restoration strategy. The importance of open tree cover and amounts of Blakely’s red gum are a matter for concern, due to a general lack of tree regeneration and the particular susceptibility of Blakely’s red gum to dieback. The scattered trees in the agricultural matrix were important to the superb parrot, suggesting that it views these landscapes as a continuum of usable habitat. Strategies for restoration of larger habitat remnants should also include regeneration of trees in scattered pattern in the wider landscape, and Blakely’s red gum should be part of any strategy along with other key species such as yellow and white box. The landscape sampling approach successfully addressed the challenges of whole-landscape research. This highlights the value of ‘off-reserve’ studies across whole landscapes.