The significance of midsummer movements of Autographa gamma： Implications for a mechanistic understanding of orientation behavior in a migrant moth

作     者：Jason W. CHAPMAN Ka S. LIM Don R. REYNOLDS 

作者机构：Department ofAgroEcology Rothamsted Research Harpenden Hertfordshire AL5 2JQ UK Environment and Sustainability Institute University of Exeter Penryn Cornwall TR10 9EZ UK Natural Resources Institute University of Greenwich Chatham Kent ME4 4TB UK 

出 版 物：《Current Zoology》 (动物学报（英文版）)

年 卷 期：2013年第59卷第3期

页      面：360-370页

核心收录：

学科分类：0905[农学-畜牧学] 09[农学] 0904[农学-植物保护] 

基　　金：funded by the UK Biotechnology and Bilolgical Sciences Research Council(BBSRC) 

主　　题：Long-range migration Dispersal High-altitude flight Photoperiod Entomological radar Noctuid moths 

摘      要：The silver Y moth Autographa gamma undertakes windbome spring and fall migrations between winter breeding re- gions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include： （i） selection of seasonally-favorable tailwinds; （ii） flying at the altitude of the fastest winds; （iii） adopting flight headings that partially counteract crosswind drift; and （iv） seasonal reversal of preferred directions between spring and fall. In the UK, ra- dar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during mid- summer （July）. However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dis- persion of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photopcriod cues during development of the summer generation resulted in randomly-oriented ＇dispersive＇ movements that were strikingly different from typical seasonal migrations .