筋骨草内昆虫蜕皮激素类似物对杨干象的杀虫作用

从不同地点、不同时间采集的多花筋骨草植株不同部位中提取出昆虫蜕皮激素类似物,通过向幼虫人工饲料中添加昆虫蜕皮激素类似物的方法,研究了筋骨草中植物源蜕皮激素对杨干象2龄幼虫的杀虫作用。实验结果表明:(1)在人工饲料中加入1-3 ml的筋骨草提取物,在24天内可以杀死 58%~100%的幼虫;(2)从开花前的筋骨草中提取出的物质的杀虫效果明显优于从花期和开花后的植物中提取出的物质的杀虫作用, 其1 mL、2 mL和3 mL剂量全株提取物的杀虫效果分别达到65.22%、85.07%和98.11%(幼虫校正死亡率);(3)植株的根部提取的昆虫蜕皮激素类似物的杀虫效果要比茎部或叶部提取的好,1 mL、2 mL、3 mL剂量提取物的杀虫效果分别达到100%、98.20%和98.32%;(4)筋骨草提取物的杀虫速度较慢,处理杨干象2龄幼虫16天后杀虫率才超过50%;(5)幼虫取食加有筋骨草提取物的饲料时间长短直接影响幼虫死亡率,16天的取食,幼虫死亡率达到80%以上。筋骨草采集地点和填加植物源蜕皮激素的方式对杀虫效果的影响较小。图3表3参21。     

中国吉林森林生态网络现状与展望

本文概要介绍了吉林省生态环境概况、林业建设成就与问题,论述了本省森林生态网络建设面临的任务及亟待解决的八个方面的问题,并对生物技术、信息技术、新材料技术及无公害森林保健技术在森林生态网络建设的应用前景进行了展望。参9。     

Citrus response to salinity: growth and nutrient uptake

To determine the effects of salinity on relative growth rate (RGR), net assimilation rate on a leaf weight basis (NAR(w)), leaf weight ratio (LWR), and nutrient uptake and utilization of citrus, we grew four citrus rootstocks (sour orange, Cleopatra mandarin, Carrizo citrange and Citrus macrophylla) in nutrient solutions containing 0, 10, 20, 40 or 80 mM NaCl for 20, 40 or 60 days. For each element analyzed, specific absorption rate (SAR) and specific utilization rate on a leaf basis (SUR(L)) were calculated for the period between Days 40 and 60. Relative growth rate decreased with time for all treatments and rootstocks. Salt treatment significantly reduced both RGR and NAR(w), whereas LWR showed no definite trend. In all rootstocks, NAR(w), but not LWR, was significantly correlated with RGR, indicating that NAR(w) was an important factor underlying the salinity-induced differences in RGR among the citrus rootstocks. At Day 60, salinity had a significant effect on leaf concentrations of Cl, Na, K, Ca, Mg, P, Fe, Mn and Zn and on the SAR and SUR(L) of most elements. In general, RGR was correlated with SAR and SUR(L). Therefore, in addition to osmotic effects and the inhibitory effects of high concentrations of Cl(-) and Na(+), an imbalance of essential nutrients may also contribute to the reduction in plant growth under saline conditions.     

Risk factors to incidental leptospirosis and its role on the reproduction of ewes and goats of Espírito Santo state,Brazil

Ovine and caprine stockbreeding have been gaining attention in developing countries as an attractive investment. On these animals, infectious diseases of the reproductive tract, such as leptospirosis, can compromise the production leading to economic losses. The present study aimed to determine the risk factors associated with incidental leptospirosis and its influence on the reproductive parameters of ewes and goats of Espírito Santo state, Brazil. A total of 737 animals distributed on 24 herds/flocks were studied, and an overall prevalence of 10.9 % seroreactive animals was observed. Serogroup Icterohaemorrhagiae was the most frequent in goats (97.0 %) as well as in ewes (78.3 %). Regarding risk factors related to leptospirosis, the presence of waterholes and the semi-intensive breeding system were the most important associated to seroreactivity. Besides, there was an observed association between seroreactivity and reproductive failures (P?<?0.05). Moreover, seroreactive ewes (relative risk (RR)?=?1.3) and goats (RR?=?1.9) presented more chances to have abortions than seronegative animals. Furthermore, seroreactive ewes presented 11.6 more chances of having premature births when compared to the seronegative ones. It can be concluded that Leptospira infection, mainly those caused incidental strains (such as Icterohaemorrhagiae serogroup), is a significant factor to reduce the productivity of small ruminants’ herds/flocks in the studied region, and environmental measures must be considered on control programs.