POPULATION DYNAMICS OF THE WHEAT STEM SAWFLY, CEPHUS CINCTUS (HYMENOPTERA: CEPHIDAE), IN WHEAT

Author:

Holmes N. D.

Abstract

AbstractThe effects of the major factors on populations of the wheat stem sawfly, Cephus cinctus Norton, were studied in the field at Lethbridge, Alberta between 1970 and 1977. Fecundity of the females, which contain an average of 32.7 eggs, is influenced by the condition and variety of host plants in which they develop as larvae. Populations of the adults that emerge from infested crops cut 7–9% by the larvae in one year may infest 70–80% of the stems of adjacent crops in the following year. Increased adult densities, however, fail to increase markedly the percentage of stems infested because the adults concentrate at field margins when they reinfest the most preferred stems. Because only one larva can mature in each stem, competition within stems that receive more than one egg causes a major drop in the population but not in the percentage of infested stems cut. Another major drop is caused by host plant resistance, which is influenced in both susceptible and resistant wheats by the weather during the growing season. On an average, all of the larvae die in 28% of the infested stems of two susceptible wheats and in 67% of those of a resistant wheat. The mortality in resistant wheats, however, is generally not sufficient to prevent economic infestations in subsequent years. Parasitism, which was a major factor in only 7 of 36 years in southern Alberta, is increased by weather conditions that cause delayed ripening of the wheat crops. The mortality of mature larvae and pupae averaged 21.3%. It is affected by extremes of moisture and temperature and can be increased slightly by shallow tillage of infested stubble.

Publisher

Cambridge University Press (CUP)

Subject

Insect Science,Molecular Biology,Physiology,Ecology, Evolution, Behavior and Systematics,Structural Biology

Reference23 articles.

1. A COMPARISON OF INJURY AND SURVIVAL OF LARVAE OF CEPHUS CINCTUS NORT. AFTER INTRACELLULAR AND EXTRACELLULAR FREEZING

2. Moisture relationships of the wheat stem sawfly (Cephus cinctus Nort.). I. Some effects of desiccation;Salt;Scient. Agric.,1946

3. The reaction of Rescue wheat to sawfly damage;Platt;Scient. Agric.,1948

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3