草地贪夜蛾生殖行为及其昼夜节律研究

Reproductive behavior and circadian rhythms of Spodoptera frugiperda

草地贪夜蛾Spodoptera frugiperda是当前跨国迁飞性重大害虫,云南是其重要虫源地及其向内地迁移的重要通道。生殖行为是性选择和物种进化的重要基础,基于生殖行为的害虫监测和防治策略也有重要价值。本研究模拟自然条件下可能出现的择偶情况,采用永久配对和每日更换配偶两种处理,对草地贪夜蛾成虫一生(约10 d)的生殖行为和节律进行了连续观测。结果表明,该蛾在羽化当日(0日龄)即出现召唤和求偶行为但无交配发生,在1日龄开始出现交配行为并在2日龄开始产卵,从2日龄到6日龄期间一直保持了较高的生殖活动,之后开始下降。雄虫求偶与雌虫召唤在节律上有较高的同步性,交配高峰多出现在召唤和求偶高峰之后。每日更换配偶与永久配对相比,雌蛾表现出较高的求偶频率和持续时间,较高交配比率和频率。雌虫在遇到新配偶或与新配偶交配后,会延缓产卵或下调产卵速率。从性选择理论来看,这些行为策略将有助于雌虫获得物质或基因利益,值得进一步探究。交配次数、召唤时长与雌虫寿命之间相关性不显著,但前5 d产卵速率与雌虫寿命间存在显著负相关,即早期产卵量较高的雌虫寿命较短,符合早期繁殖-后期存活基因拮抗假说。

Spodoptera frugiperda is currently a major transnational migration pest.Yunnan is an important source of this insect and a key channel for its migration to the inland.Reproductive behavior is an important foundation of sexual selection and evolution,and it is also of great value for pest monitoring and control based on reproductive behavior.This study simulated the mate selection situation that might occur under natural conditions,and set two treatments-permanent pairing(PM)and change mate daily(CM),and then continuously observed the lifetime(about 10 days)reproductive behavior and rhythm of the adult in S.frugiperda.Calling and courtship behaviors were observed on the day of eclosion(0 d old)but no mating occurs this day.Mating started to occur in 1 d old moths and oviposition started in 2 d old moths.The reproductive activities were maintained at a high level from 2 d old to 6 d old,and then declined afterwards.The rhythms of male courtship and female calling showed a high synchronization,and the peak of mating usually occured after the peak of calling and courtship.Compared with PM treatment,female from CM treatment exhibited higher courtship frequency and duration,and higher mating rate and frequency.After a female encountered a new mate or mated with a new mate,she might delay egg laying or slowdown the rate of laying eggs.From the perspective of sexual selection,these behavioral strategies would help females obtain material or genetic benefits,which warranted further study.There was no significant correlation between mating times and female lifespan or between calling duration and female lifespan,but there was a significantly negative correlation between egg laying rate in the early stage and female lifespan,that was,females with higher early egg production had shorter lifespan,and vice versa,which was consistent with the gene antagonism hypothesis between early reproduction and later survival.