枣实蝇对寄主植物不同器官的选择性测定

[目的]为枣实蝇引诱剂的研发提供理论依据。[方法]从枣实蝇行为学研究入手，以“Y”型嗅觉仪分别测试了枣实蝇对红枣和杏两种寄主植物不同新鲜器官的选择行为。[结果]表明，不同性别的枣实蝇成虫对寄主植物枣和杏不同器官的选择性表现出一定差异。雌虫对枣果的选择性比叶片和花的要强（P<0.05），对枣果、枣花、叶片三者的选择率分别为35%、25%、22%；从枣果不同发育期（青果期、半红期、全红期）的选择性来看，雌虫对半红期枣果的选择性最强，选择率为38%，青果次之，为35%。而雄虫对枣花的选择性较强，选择率为38%，半红期枣果次之，为32%。枣实蝇对杏树不同器官的选择性来看，对果实的选择性比叶片的选择性要强（P<0.05），从杏果（青果、熟果）不同发育期的选择性来看，雌虫对青果的选择性最强，选择率为30%，熟果次之，为28%。雄虫对熟果的选择性较强，选择率为28%，与青果、叶片有显著差异（P<0.05）。[结论]同一性别不同生理状态的成虫对寄主植物不同器官的选择性表现出一定差异，性成熟的成虫比未性成熟的成虫对寄主植物的选择性要强。性成熟的枣实蝇雌成虫对半红期枣果的趋性强于枣花与叶片     

Total Replacement of Dietary Fish Oil with a Blend of Vegetable Oils in the Marine Herbivorous Teleost,Siganus canaliculatus

To investigate the feasibility of total replacement of dietary fish oil (FO) with vegetable oils (VOs) and the optimal dietary polyunsaturated fatty acid (PUFA) level in the marine herbivorous teleost Siganus canaliculatus, six isonitrogenous (32%) and isolipidic (8%) diets were formulated. Control diet used FO as lipid source, whereas diets VO1–VO5 contained various blends of palm, soybean, rapeseed, and linseed oils, in which the dietary PUFA levels were 42.0, 38.2, 33.8, 29.9, and 27.1%, respectively. After S. canaliculatus juveniles were fed with the diets for 9 wk, their growth performance exhibited no significant difference among the dietary groups. The tissue fatty acid (FA) profiles in liver and fillet generally reflected the dietary FA compositions and showed no significant difference among the VO dietary groups. The results suggest that dietary FO can be replaced completely by VO, without affecting their growth performance. Concerning the effects of the dietary FA profile on the survival rate, hepatosomatic index and viscerosomatic index, and PUFA composition in fillets, diets VO1 and VO2 were more favorable compared with diets VO3–VO5. Considering the availability and cost of the VOs, diet VO2 was recommended for practical use in S. canaliculatus.     

Habitat specialization and sensitivity to change in a threatened crayfish occupying upland streams

1. Crayfish are culturally and ecologically important species in freshwater ecosystems, but many are now threatened with extinction, due to threats such as habitat loss. Depending on their habitat selectivity and sensitivity, freshwater crayfish could provide effective targets for stream monitoring, restoration and conservation. This study used repeated field surveys of the threatened Murray crayfish, Euastacus armatus (family Parastacidae), to establish their habitat preferences and sensitivity to habitat loss across mesohabitat and microhabitat scales within upland streams of south‐east Australia. 2. Selectivity analysis revealed that upland populations of E. armatus displayed a strong preference for areas of intermediate water flow velocity, deeper water, and stream beds dominated by boulders and gravel. Variations in E. armatus density among and within the two upland streams aligned with these microhabitat preferences, with best‐subsets analyses revealing that E. armatus abundance hotspots were best predicted by models combining water depth with percentage cover of boulders, gravel and overhanging riparian vegetation. 3. Major shifts in stream habitat condition from 2009 to 2015 (e.g. 32% and 50% decline in boulder and overhanging vegetation cover, respectively) was associated with a 91% decline in E. armatus mean density within glide‐pool mesohabitats. 4. These findings highlight how habitat specialization in threatened crayfish such as E. armatus may render them sensitive to changes in stream habitat condition, and how targeted monitoring, restoration and conservation of their preferred habitats could yield multiple benefits for montane freshwater ecosystems. Copyright © 2016 John Wiley & Sons, Ltd.     

Evidence of synergy with ‘stacked’ intrarow cultivation tools

Intrarow cultivation efficacy is often low and highly variable. As the mechanisms affecting weed mortality likely vary by tool, several companies have developed cultivators with the ability to use several different intrarow tools at once. We evaluated the potential for such ‘stacking’ of cultivation tools to increase efficacy. We used different sequences of torsion weeders, finger weeders and row harrows in a test crop of maize with surrogate weeds, Sinapis alba and Panicum miliaceum. Most tool combinations resulted in an additive increase in efficacy compared with the individual tools, but the combination of torsion–finger–row harrow demonstrated a synergistic increase in efficacy. In separate experiments, forward speed, soil moisture and weed size were negatively correlated with efficacy, but the torsion–finger–row harrow combination continued to demonstrate a synergistic increase in efficacy compared with the individual tools in 7 of 11 cases. The drawback was high crop mortality (16.0 ± 1.16%); further mechanistic research is needed to reduce crop mortality while maintaining high mean efficacy, through tool design, adjustment and cultural factors.     

草甘膦助剂的选择与展望

本文从助剂对草甘膦活性的作用机理出发,介绍了不同草甘膦助剂的应用特点以及不同草甘膦盐对助剂的选择性。通过复配助剂在草甘膦制剂中的应用实例,展望了草甘膦制剂的未来发展方向。     

竹子深度脱木质素蒸煮与常规硫酸盐法蒸煮的比较

为了提高竹浆性能和减少环境污染,对福建丛生小径竹进行了实验室模拟延伸改良连续蒸煮(EMCC)和常规硫酸盐法蒸煮(CKC)的研究。结果表明,EMCC蒸煮通过分段加入蒸煮药液和在逆流段进行药液置换,比CKC具有更高的脱木质素选择性。在蒸煮相同卡伯值的竹浆时,EMCC浆比常规硫酸盐浆(CK浆)具有更高细浆得率、较低粗渣率、更高粘度和更好强度性能。在相同的打浆度下,EMCC浆抗张指数、耐破指数和撕裂指数都比常规硫酸盐浆高。