甜菜夜蛾核型多角体病毒在宿主种群中的垂直传播研究

Vertical transmission of Spodoptera exigua nuclear polyhedrosis virus in the beet armyworm, Spodotera exigua

以两种浓度的病毒液感染甜菜夜蛾4龄、5龄幼虫,以研究甜菜夜蛾核型多角体病毒从亲代到子代垂直传递的方式和效率。实验结果表明,该病毒可通过母体介导(卵内、卵表)和父体介导等3种方式传递给子代,造成子代感染。幼虫经口感染后母体介导传递实验表明,病毒垂直传播可引起20%～48%的子代幼虫病死,并能使子代成虫产卵量下降;母体介导传播实验中,以5%福尔马林进行卵表面消毒证实仍有18.8%的幼虫感染病毒死亡,表明了该病毒可经卵内传播,并同时存在着附卵传播;母体介导传递实验还表明病毒对宿主有弱化作用,亲代免于病死的蛹重量减轻,羽化所得雌成虫的产卵量下降,产卵期延长。以交互配对将感染与未感染的雌雄成虫彼此交配,表明雄成虫精子也能垂直传递病毒(父体介导),引起20%～40%子代幼虫感病死亡。成虫经口感染,对所产卵块表面消毒后,仍导致28.6%的子代幼虫死于病毒感染,也表明存在卵内传播。

The experiments were conducted to determine the transmission mode and rate of Spodoptera exigua nuclear polyhedrosis virus （SeNPV） from the infected parents to their progeny through feeding the 4th and 5th instar larvae with the concentrations of 2.8 ×10^7 and 2.8 ×10^6 PIBs · mL^-1 in the laboratory. The results showed that SeNPV could be transmitted to the offspring by three modes, i.e. transovarian, transovum, and aduh mating. The female-mediated vertical transmission test indicated that the adults developed from virus-infected larvae transmitted the virus to their progeny, resulting in 20% -48% mortality of the next generation （Ft） and decrease of the fecundity of F1 progeny adults compared with untreated controls. Moreover, the experiment with surface of the egg sterilized by 5 % formalin solution showed that SeNPV could be transmitted to larvae of F1 generation by transovarian transmission, which caused 18.8% mortality of F1 generation. The crossing experiments between virus-infected and non-infected females and virus- infected and non-infected males indicated that virus could also be transmitted to F1 generation by sperm of male adult, which caused 20% -40% mortality of offspring larvae. Furthermore, through the experiment of adult oral infection, it was found that SeNPV could also be transmitted to offspring at a prevalence rate of 28.6 %.