THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT

Investigations were made of the degree of infestation of plants grown in light soil and in clay soil sown at different dates. The plants sown late in the season in light soil were more affected by the thrips, the infestation being relatively high almost from the germination of the plant and causing death before the flowering stage was reached. On the blocks of plants in light soil sown earlier in the year the infestation was relatively low for a considerable period, and although, at the end of the season, the thrips became very numerous on these plants it was not until after the bolls had been formed, and in this case the practical damage was small.
The plants sown in clay soil at different dates did not show such a marked difference in the degree of infestation, and all were less infested by the insects than the corresponding blocks of plants in light soil. This corroborates the findings of previous experiments, namely, that plants grown in light soil are found to be more heavily infested by T. tabaci than plants grown under similar conditions in clay soil.
I should like to take this opportunity of thanking Prof. Dunkerly for his helpful criticism, Miss R. M. Smith and Mr I. Thomas for their assistance in making the counts, and Mr R. Stewart for his analysis of the soils used.     

山羊草属核型分析及其与小麦属的进化关系

作者研究了山羊草属(Aegilops)中的新疆节节麦(Ae.squarrosa)、拟斯卑尔脱山羊草(Ae.speltoides)、沙融山羊草(Ae.sharonensis)、尾状山羊草(Ae.caudata)、卵圆山羊草(Ae.ovata)、偏凸山车草(Ae.ventricosa),钩状山羊草(Ae.triuncialis)、三芒山羊草(Me.triaristata)、欧山羊草(Ae.biuncialis)、柱穗山羊草(Ae.cylindrica)、可兹山羊草(Ae.kotschyi)和肥厚山羊草(Ae.crassa)的核型和部分材料的Giemsa N-带,结果表明山羊草属的C组核型为:4sm+3st;D组核型为:6m+1sm;S组的核型为:6m+1sm;M组的核型为:4m+1sm+2t。在四倍体、六倍体中,各染色体组保持着相对稳定。山羊草属S、D染色体组的核型与带型表明它们是小麦B、D染色体组的可能供体,C、M染色体组的一部分染色体带型亦与小麦B组带型相似。     

治理有害动物的战略与策略——主要以中国棉虫为讨论材料

前言 有害动物,本文着重谈其中的有害昆虫。所谓有害,是指这些动物或昆虫对人类生命和生活起着有害的作用。地球上已知约一百万种昆虫中,一部分对人类造成严重灾害。举若干有数据可查的例子来说:美国约有一万种害虫和螨类,其中约七百种(212种从国外传入)为害比较严重(smith、et al.1973,p.446)。世界上棉花害虫的记载有1,326种(Hargreaves,1948),美国有一百种左右昆虫和螨类为害棉花,1951—1960年平均年损失五千万美元,约为年产量的19％(Metcalf et al.1975,p.379)。印度1963—1964年因虫害损失粮食15％,约计1,300万吨。Cramer(1969)根据世界各地许多资料分析研究,估计世界上农业因虫害损失每年产量的13.8％,约值200—300亿美元。