税收优惠政策对农业科技创新影响的研究

我国的相关农业税收优惠政策能够对农业科技起到一定的促进作用,却对相关的研发 投入具有消减作用,对相关的人力投入的激励作用也不够明显。本文研究我国的税收优惠政策 对当前农业科技创新的重要影响,分别从促进农业企业的市场竞争力、降低农业科技创新的融 资风险、增加人才培养和引进、提供信贷优惠等方面进行探讨。     

Allochrony as a potential driver for reproductive isolation in adaptive radiations of European whitefish ecomorphs

In northern Fennoscandian lakes, monophylogenetic lineages of postglacial fishes are radiating into several adaptive forms, but the speciation process is still at an incipient stage. The speciation process has received increased attention over the years, but the underlying mechanisms and drivers are still debated and poorly understood. European whitefish (Coregonus lavaretus [L.]) is the most abundant fish species in these lakes and has evolved into several ecomorphs adapted to different trophic niches and habitats. Genetic divergence has been observed among these ecomorphs, but the mechanism(s) responsible for the ongoing build-up of reproductive isolation has still to be revealed. As these systems are young in evolutionary time (<10 kyr), prezygotic and postzygotic extrinsic isolation mechanisms are thought to be more likely to contribute to the reproductive isolation than intrinsic isolation mechanisms. We determined the gonadosomatic index (GSI) of three ecomorphs in two replicated lake systems and used GSI as a proxy to investigate the prezygotic isolation mechanism, allochrony, as a driving factor of divergence in this adaptive radiation of whitefish. We found that the three ecomorphs differed in GSI values within and between lakes, suggesting different spawning times of the ecomorphs. We also show that males of one ecomorph had equal onset of maturity as another ecomorph, giving novel insights into the ongoing gene flow observed between ecomorphs. The result supports allochrony as a driver for the divergence process of whitefish ecomorphs, but more evidence is still needed to rule out that the three ecomorphs make use of different spawning grounds.     

羊口疮病毒B2L基因密码子偏好性分析

B2L蛋白是羊口疮病毒(ORFV)的主要囊膜蛋白,为重要保护性抗原之一,可刺激机体产生强烈的抗体反应。本研究对B2L基因运用Visual Gene Developer生物信息学软件,分析其在大肠杆菌、毕赤酵母、昆虫杆状病毒表达系统中的密码子使用偏好性,从而选择一个最适表达系统,以增加B2L蛋白的表达量。分析表明,B2L基因在昆虫杆状病毒表达系统中会得到更好的表达,这为B2L基因表达系统的选择提供了参考。     

中蜂对不同蜂花粉的取食偏好

以来自不同地区的10个蜂花粉,在云南及重庆两地的缺粉季节饲喂中蜂蜂群,探索中蜂对花粉取食的偏好。研究结果显示中蜂蜂群对来自不同地方不同种类的花粉有选择偏好性,对同种花粉选择差异性不显著,发现中蜂对所用的山东茶花粉的取食量最大。     

瓜蚜对不同甜瓜品种的取食选择性

选择7个不同甜瓜品种,综合比较了瓜蚜对不同品种室内离体叶片的取食选择性及在室外活体植株上的种群增长动态。结果发现,瓜蚜对IVF437和羊角蜜的叶碟选择性比其他品种低,叶碟选择2 h后羊角蜜和IVF437上的瓜蚜数量为2~3头,选择率为5.54%~7.38%;培养12 h后,羊角蜜和IVF437上的若蚜分别为5.50头和14.00头。且瓜蚜在这2个品种上的种群增长速度也较慢,研究结果为田间甜瓜品种的选择种植及进一步选育抗蚜品种提供了科学基础。     

Seasonal variations in the diet and food selection of the Algerian hedgehog Atelerix algirus

The Algerian hedgehog Atelerix algirus is an insectivorous species. However, the exact composition of its natural diet remains largely undetermined, especially in relation to seasonal variations in food availability. From March to November, we simultaneously analysed the composition of 180 hedgehog faecal samples and food availability in the Soumman Valley, Algeria to assess food selection in this species. The faeces contained 196 different prey species, of which 92% belonged to the class Insecta. The highest prey species diversity was found in the Coleoptera order (100 species recorded) and the highest species occurrence was found in Hymenoptera (65% of the prey items, mainly represented by the harvester ant Messor barbarus, a crop-ravaging species). This study shows that the Algerian hedgehog is mainly a generalist species with a diet that is strongly linked to food availability. However, seasonal variations were observed in prey selection, and a notable shift in food preference was observed during autumn. The exact nature of these changes in feeding behaviour remains to be investigated, notably in relation to changes in energy requirements of this species before hibernation, in terms of quantity and/or quality.     

A comparison of food habits and prey preferences of Amur tiger (Panthera tigris altaica) at the southwest Primorskii Krai in Russia and Hunchun in China

A small, isolated Amur tiger population ranges across the southwest Primorskii Krai region in Russia and Hunchun region in China. Many individuals, with “dual nationality,” cross the border frequently. Formulating effective conservation strategies requires a clear understanding of tiger food requirements in both countries. While the diets of tigers ranging in Russia is clearly understood, little is known of the tigers' feeding habits in China.. We used scat analysis combined with data on the abundance of 4 prey species to examine Amur tiger diet and prey preferences in Hunchun. We examined 53 tiger scat samples from 2011 to 2016 and found that tigers preyed on 12 species (11 species in winter), 4 of which were domestic animals with 33.58% biomass contribution; this was the first record of Amur tigers eating lynx in this area. Tigers showed a strong preference for wild boar (Jacobs index: +0.849), which were also the most frequently consumed prey, and a strong avoidance of roe deer (Jacobs index: ?0.693). On the Russian side, domestic animals (just dog) were rarely found in tiger scat, and tigers did not show strong avoidance of roe deer, but of sika deer. We also found red deer footprints during winter surveys and that tigers ate red deer on the Chinese side, while there was no record of red deer feeding on the Russian side. Reducing or eliminating human disturbance, such as grazing, is essential to recovering tiger prey and habitat in this area and the Sino‐Russian joint ungulate annual survey is indispensable for prey estimates of this small, isolated Amur tiger population.     

小菜蛾产卵对寄主的选择性及其应用初步研究

以广州,深圳种植的几种主要十字花科蔬菜,研究了小菜蛾对寄主的选择性,室内试验和田间调查结果基本一致,小菜蛾对芥菜,菜心的嗜好性最大,对萝卜,白菜次之,对芥蓝,花椰菜最差,根据小菜蛾喜受在芥菜上产卵这一特性,进行了芥菜与芥蓝套种诱集防治小菜蛾的田间试验,结果表明,所有套种田中芥蓝上的小菜蛾卵数量都显著低于单种田（Ｐ〈０．０５）,在芥蓝生长后期,单种田芥蓝中卵数量高出套田近１０倍,芥菜中数量是芥蓝中的     

菜蛾绒茧蜂的寄主选择性及寄生对寄主发育和取食的影响

研究了菜蛾绒茧寄生对寄主幼虫龄期的选择性及对寄主生长发育、取食量的影响。结果表明,该蜂能寄生小菜蛾各个龄期的幼虫,但当２－４龄幼虫同时存在时,偏爱寄生２、３龄幼虫,对２、３、４龄幼虫的选择系数分别为０．３７、０．３９、０．２４。该蜂对４龄幼虫的寄生能力随寄主日龄增大而急剧下降,对进入４龄并发育至该龄期４０％时间以上的幼虫不能寄生。产卵寄生的雌蜂比例也随４龄幼虫日龄增大而急剧下降。小菜蛾幼虫被寄主后