草地贪夜蛾不同日龄飞行对生殖及寿命的影响

Effects of flight at different ages on reproduction and longevity of Spodoptera frugiperda

为阐明草地贪夜蛾起飞蛾龄以及迁飞在种群成灾中的作用,本文研究了草地贪夜蛾不同蛾龄飞行对其生殖及寿命的影响,为草地贪夜蛾迁飞规律和致灾机制的解析提供理论依据。通过对不同日龄的雌蛾进行吊飞飞行试验,测定其飞行能力的变化以及对雌蛾后续生殖和寿命的影响。结果表明,羽化后不同日龄的雌蛾吊飞8 h的飞行能力差异显著(P<0.05)。1日龄雌蛾即具有较快的飞行速度,但飞行时间和距离最短。随着蛾龄的增加雌蛾飞行能力增强,3~6日龄时飞行能力达到最强(4日龄飞行速度除外),7日龄时飞行能力下降。与未飞行的对照相比,1、2日龄雌蛾吊飞8 h处理的产卵前期无显著变化(P>0.05),但3日龄吊飞8 h后产卵前期则显著延长(P<0.05);1日龄吊飞后产卵量显著增加,3日龄吊飞后则显著减少(P<0.05);1~3日龄雌蛾吊飞后产卵历期、交配率和寿命均无显著变化(P>0.05);种群产卵同步性(PFO)在2日龄吊飞后显著加强,且1~3日龄吊飞后PFO四分位间距均小于对照。这表明,草地贪夜蛾雌蛾可能在羽化后1~2日龄起飞,此时飞行不仅不会付出生殖代价,而且还会一定程度地促进成虫快速产卵、提高产卵量并增强种群产卵同步性,从而容易造成田间迁入种群快速、集中产卵,导致孵化的幼虫数量同时急剧上升,引起迁飞成灾。

In order to clarify the age of Spodoptera frugiperda for initial flight and the role of migration in the population disaster,this study investigated the effects of flight at different ages on S.frugiperda reproduction and longevity,which may provide a theoretical basis for understanding the migration and disaster caused by S.frugiperda.The flight capacity of female moths at different ages and the effects on subsequent reproduction and longevity were measured.The results showed that the flight capacity of female moths of different ages after tethered flight for eight hours was significantly different(P<0.05).S.frugiperda had faster flight velocity at the age of one day-old,but shortest flight duration and distance.With the increase of moth age,the female moths’flight capacity was enhanced,reaching the maximum at the age of three to six day-old(excluding the age of four day-old),but decreasing at the age of seven day-old.Compared with the control group without flight,the flight group had no significant change in the pre-oviposition period of female moths at the age of one day-old and two day-old after flight for 8 h(P>0.05),but it was significantly prolonged after flight at the age of three day-old(P<0.05).The lifetime fecundity of female moths was significantly increased after flight at one day-old,and decreased significantly at three day-old.There was no significant difference in the oviposition period,mating rate and female longevity of one day-old to three day-old female moths tethered flight for 8 h(P>0.05);the period of first oviposition(PFO)was significantly enhanced after flight at two day-old,and the quartile spacing of PFO after flight at one to three day-old was smaller than that of the control group.This results indicated that initial flight during the age of one to two day-old after emergence imposed no cost on the reproduction of S.frugiperda females,but promoted the rapid oviposition of adults,increased the lifetime fecundity,and enhanced the period of first oviposition.In other words,the initial flight during the age of one to two day-old after emergence of S.frugiperda females is easy to cause a sharp increase in the number of eggs and larvae,and lead to a disaster in the field.