Bilateral apex pubis distance：a novel index for follicular development and egg laying status in domestic hens (Gallus gallus domesticus)

ABSTRACT

1. Measures of the bilateral apex pubis (BAP) in White Leghorn (WLH) hens aged from 16 to 64 weeks (from the time ovaries were completely undeveloped to senility) were ranked into various groups so the relationship between external traits (BAP distance, comb length, comb height, wattle length, wattle height, body weight) and internal traits (largest ovarian follicle diameter (LFD) and oviduct weight and length) could be determined.

2. Using correlation and regression analysis with data from 16 weeks of age to the onset of lay, measurements of the apex pubis showed a strong correlation with LFD (r = 0.80, P < 0.01) and oviduct weight (r = 0.80, P < 0.01).

3. Multiple comparisons among WLH hens from 16 to 43 weeks of age showed that the BAP distance increased in all groups ranked by LFD or by laying period.

4. In the late laying period (>60 weeks of age), BAP distance showed a significant decrease (P < 0.01) in long-term non-laying hens compared to laying hens.

5. These findings suggest BAP distance can serve as an index for evaluating the onset and probable stages of follicular development during sexual maturation and/or aid in the identification and selection of non-laying hens during reproduction.     

松树截根菌根化育苗和造林的研究*

根据苗木根系分泌物能促进菌根真菌萌发和生长的原理，结合我国林业育苗的特点，提出了松树幼苗截根与人工接种菌根真菌结合的育苗方式。结果表明，截根菌根化育苗在促进根系发育和菌根形成，加速苗木生长，提高苗木生物量、苗木质量和产苗量等方面都有显著优势，苗木的侧根数、侧根总长、苗木菌根化率、吸收根菌根化率、苗高、地径、鲜重、干重分别提高２０．０％～９６０．０％、５６．２％～３８９．５％、０．０％～４００．０％、５６．２％～１７９２．０％、２２．３％～１７９．３％、３１．２％～２５３．８％、３３．３％～９１８．２％和２１．８％～７４０．０％，苗木成活率和Ⅰ级苗分别提高９．０％～２２．１％和４９．３％～１５０．０％，Ⅱ、Ⅲ级苗和等外苗分别降低４０．６％～７７．３％、６１．６％～８８．５％和８２．５％～１００．０％。利用截根菌根化苗木造林，提高成活保存率５．５％～４６．０％，并促进幼树生长，树高、地径和材积指数分别增加１３．０％～５６．４％、２５．５％～６１．７％和８７．８％～４５０．０％。效益分析证明，截根菌根化育苗具有明显的经济效益和社会效益，仅苗期可定量计算的增收（节支）总额可达４４６６２元／ｈｍ２。     

杭州悬铃木方翅网蝽的捕食性天敌种类及日本通草蛉幼虫捕食作用

本文调查发现杭州悬铃木方翅网蝽Corythucha ciliata(Say)的捕食性天敌有5科7种,主要是日本通草蛉Chrysoperla nipponensis(Okamoto)、普通草蛉Chrysoperla carnea(Stephens)和小花蝽属Orius spp..日本通草蛉幼虫对悬铃木方翅网蝽成虫、若虫的捕食功能反应均符合Holling Ⅱ型方程,捕食作用强弱为:日本通草蛉3龄幼虫捕食若虫＞日本通草蛉2龄幼虫捕食若虫＞日本通草蛉3龄幼虫捕食成虫,其对应的搜寻效率α与处理时间Th值分别为1.0141、0.5687、0.3757和0.0075、0.0121、0.0267.成虫和若虫共存时,日本通草蛉3龄幼虫喜好捕食若虫.日本通草蛉幼虫的搜寻效应随猎物密度的增加而降低.在悬铃木方翅网蝽若虫密度相同的条件下,日本通草蛉2龄、3龄幼虫随着自身密度的增大,其平均捕食量逐渐减少,捕食作用率也相应降低,其捕食作用率E与自身密度P的关系分别为:E=0.3164 P-0.4700和E=0.3411 P-0.4762.日本通草蛉幼虫间存在分摊竞争.     

Challenges facing arthropod biological control: identifying traits for genetic improvement of predators in protected crops

Biological control is an efficient pest control method but there are still limitations that are hindering its wider adoption. Genetic improvement of biological control agents (BCAs) can help to overcome these constraints, but the choice of key attributes for better performance that need to be selected is still an open question. Several characteristics have been suggested but the harsh reality is that selective breeding of BCAs has received a lot of attention but resulted in very little progress. Identifying the appropriate traits to be prioritized may be the first step to reverse this situation. In our opinion, the best way is to look at the factors limiting the performance of key BCAs, especially generalist predators (pesticide compatibility, prey‐density dependence, non‐suitable crops, and extreme environmental conditions), and according to these challenges, to choose the attributes that would allow BCAs to overcome those limitations. The benefits of selection for higher resistance to toxins, whether artificially applied (pesticides) or plant produced (plant defenses); increased fitness when feeding on non‐prey food (supplemented or plant‐derived); and better adaptation to extreme temperature and humidity are discussed. In conclusion, genetic improvement of BCAs can bring about new opportunities to biocontrol industry and users to enhance biocontrol resilience. © 2020 Society of Chemical Industry     

何首乌茎尖嫩叶主要营养成分分析及评价

测定了何首乌茎尖嫩叶的VB2、VC、粗纤维等主要营养成分含量和K、Fe、Zn等矿质元素含量,以期为何首乌茎尖嫰叶的合理开发利用提供理论依据。结果表明,何首乌茎尖嫩叶营养丰富,各种营养成分较为全面,其主要营养成分和矿质元素含量也远远高于其他4种常见蔬菜,这为何首乌茎尖嫩叶的食用价值提供了科学依据,也为改善人们的膳食营养和餐饮文化、开发蔬菜资源及提高其利用价值提供了参考。     

Turbidity‐induced changes in emergent effects of multiple predators with different foraging strategies

Abstract – In natural systems, prey frequently interact with multiple predators and the outcome often cannot be predicted by summing the effects of individual predator species. Multiple predator interactions can create emergent effects for prey, but how those change across environmental gradients is poorly understood. Turbidity is an environmental factor in aquatic systems that may influence multiple predator effects on prey. Interactions between a cruising predator (largemouth bass Micropterus salmoides) and an ambush predator (muskellunge Esox masquinongy) and their combination foraging on a shared prey (bluegill Lepomis macrochirus) were examined across a turbidity gradient. Turbidity modified multiple predator effects on prey. In clear water, combined predators consumed in total more prey than expected from individual predator treatments, suggesting risk enhancement for prey. In moderately turbid water, the predators consumed fewer prey together than expected, suggesting a risk reduction for prey. At high turbidity, there were no apparent emergent effects; however, the cruising predator consumed more prey than the ambush predator, suggesting an advantage for this predator. Understanding multiple predator traits across a gradient of turbidity increases our understanding of how complex natural systems function.     

小麦茎顶端原基发育模拟模型的研究

本文系统地模拟了小麦植株茎顶端不同类型原基的发育过程，建立了叶原基分化、小穗原基分化和小花原基分化、退化、败育、受精结实及籽粒生长的子模型。模型引入每小穗分化的最大小花原基数、退化的最大小花原基数和籽粒潜在重量3个遗传参数，分别反映了不同小麦品种小花分化、退化和籽粒生长等方面的遗传差异。利用南京地区     

Reedbeds as refuges for water voles (Arvicola terrestris) from predation by introduced mink (Mustela vison)

The water vole has recently undergone a catastrophic decline in the UK. This has resulted from loss and fragmentation of suitable habitat leaving water vole populations highly vulnerable to the impact of predation by introduced American mink. However, at some reedbed sites water voles and mink have apparently coexisted for many years. To determine if reedbeds offer a refuge from predation, 70 voles were radio-tagged at three sites in England and overwinter mortality monitored. Water vole perception of predation risk was also assessed. Mortality was high (64%), predation by mustelids, including mink, being the chief cause. Experiments suggested that voles failed to perceive areas of highest predation risk. However, predation rate declined strongly with the distance water voles lived from a main water channel. Thus, reedbeds provide a refuge from predation, even by mink, and calculations suggest that they may support source populations enhancing the viability of water vole metapopulations. Consequently reedbeds are now being used as one focus for the conservation of water voles in England and Wales.     

Lotka-Volterra数学模型在草地管理中的应用

介绍了Lotka-Volterra数学模型建立、求解方法,详细讨论了该模型在草地生态系统中的应用特点。通过分析认为可以利用Lotka-Volterra模型调控草地生态系统中载畜量与草地牧草产量间的关系,从而准确指导草地畜牧业生产。