棉长管蚜诱导棉花的防御反应对棉长管蚜和棉蚜种间竞争的影响

Acyrthosiphon gossypii Mordvilko．offen appear earlier than Aphis gossypii Glover in cotton fields. Although A. gossypii Mordvilko．population is larger at the prophase of cotton growth stage, it has not more competitive advantage in the middle and late period of cotton growth, which be coexisting with A. gossypii Glover. The effect of cotton's defense response induced by A. gossypii Mordvilko．on development and reproduction of A. gossypii Glover is not clear yet. Based on this, we study on the preference of A. gossypii Mordvilko. and A. gossypii Glover to healthy cotton plants and infested by intraspecific and interspecific aphids based on variation of population of cotton aphids, and on competitive behavior of the defense response to this two aphid species of cotton plants induced by A. gossypii Mordvilko．We study on biochemical and molocular mechanisms of defense responses to A. gossypii Glover of cotton plants induced by A. gossypii Mordvilko. to probe competitive mechanism between A. gossypii Mordvilko. and A. gossypii Glover.. The differences of sap composition and contents in cotton leaves and phloem before and after infested by A. gossypii Mordvilko．are studied to determine what activated defensive factor to A. gossypii Glover. We also study on the changes of key enzyme activity, and the contents of the jasmonic acid and salicylic acid to determine the role of JA and SA-mediated defense signaling pathways in cotton plants induced by A. gossypii Mordvilko．The differences of physiological adaptation between A. gossypii Mordvilko. and A. gossypii Glover. are also studied to explore effects of physiological adaptability of the two kinds of insects in interspecies competition. It is very important to reveal competition mechanism between A. gossypii Mordvilko. and A. gossypii Glover., and scientifically control cotton aphids.

棉长管蚜比棉蚜早出现在棉田，种群数量大，与棉蚜能共存，但中后期没有明显的竞争优势，前期取食诱导棉花防御反应对棉蚜的影响尚不清楚。基于此，通过棉株上棉蚜和棉长管蚜种群数量变化，分析蚜虫种内种间对受害和健康植株的偏好性，研究诱导棉花防御反应对棉长管蚜和棉蚜种间竞争行为的影响。研究棉长管蚜诱导棉花对棉蚜防御反应的生化和分子机制，探讨在棉花上棉蚜对棉长管蚜竞争优势的机理。比较研究棉长管蚜取食前后棉花叶片和韧皮部汁液中成分的变化，探明棉长管蚜诱导棉花产生对棉蚜有抑制活性的防御因子；通过SA和JA介导的防御信号途径的关键酶活性、信号物质茉莉酸和水杨酸的含量变化，探明SA和JA两种防御信号途径在棉长管蚜诱导的棉花对棉蚜防御中的作用；通过研究棉蚜和棉长管蚜在生理适应性方面的差异，探讨其生理适应性在两种昆虫种间竞争中的作用。对于进一步揭示棉长管蚜与棉蚜竞争机制，科学治理棉田蚜虫具有重要的理论和实践意义。

棉长管蚜比棉蚜早出现在棉田，种群数量大，与棉蚜能共存，但中后期没有明显的竞争优势，前期取食诱导棉花防御反应对棉蚜的影响尚不清楚。通过项目实施，发现棉长管蚜对棉蚜取食的棉花有耐受性，不排斥和棉蚜共同取食同一株棉花，且长期共存。棉蚜对胁迫的棉花选择具有趋避性，更偏好健康棉花，这种选择更容易使其在棉田进行扩散成灾。棉蚜比棉长管蚜更能适应诱导的棉花。种内竞争对棉长管蚜和棉蚜种群数量产生负效应，种群密度对棉蚜各龄期发育没有显著影响。棉蚜的净增率和内禀增长率都大于棉长管蚜，说明棉蚜比棉长管蚜更有竞争力。棉长管蚜和棉蚜蜜露分泌量都随着龄期的增加而增加，且平均每只蚜虫白天的分泌量大于夜间的分泌量。蜜露对无翅棉长管蚜选择具有一定的趋避性，而有翅棉长管蚜有偏好性。无翅棉蚜喜欢选择无蜜露寄主，有翅棉蚜对棉长管蚜选择蜜露不敏感。棉长管蚜取食可以改变棉花体内与营养代谢和细胞渗透压调节相关物质，及次生代谢途径中重要化合物的合成与代谢。棉长管蚜取食引起棉花6565个基因差异表达，92%的差异基因出现在代谢途径和次生代谢产物的生物合成途径中。棉长管蚜取食棉花可以延长后取食棉蚜的发育时间，降低雌成蚜寿命及产蚜量，中、高密度棉长管蚜取食棉花可以降低棉蚜存活率，棉长管蚜取食棉花后可以减缓棉蚜种群的增长速率，也可以一定程度上降低棉蚜种群数量。棉长管蚜诱导棉花、棉长管蚜-棉蚜依次诱导棉花以及交互诱导可以激活棉花的防御反应，而当棉蚜和棉长管蚜再次取食蚜虫诱导过的棉花后，体内与营养物质消化吸收、有毒物质降解及维持活性氧系统动态平衡的关键酶活性发生变化，以此来适应棉花对棉蚜和棉长管蚜的防御。而在两种蚜虫对棉花防御的适应性方面，棉蚜更胜一筹，可以明确了其为棉花生长中后期田间优势种。本研究对科学治理棉田蚜虫具有重要的理论和实践意义。