大菜粉蝶颗粒体病毒对菜粉蝶幼虫取食、生长、发育的影响

菜粉蝶幼虫在一、二、三、四龄初期饲以大菜粉蝶颗粒体病毒(PbGV),食量减少99.3—38.4%;四龄末或五龄初饲毒,食量反而比健虫高出36.3%和87.2%。幼虫感病后取食期的缩短或延长是食量变化的主要原因。幼虫病死前脱皮过程先被抑制,其结果往往使得死亡时所处的龄期明显延长。幼虫在四龄末饲毒后,由于五龄期延长,食量增加,其死亡前达到的最高体重平均为357.9毫克,远高于健虫化蛹前的最高体重。PbGV对菜粉蝶化蛹也有明显影响。幼虫在五龄前饲毒,一般不能化蛹。五龄第1—3天饲毒,化蛹率26.4—87.9%,第4天饲毒对化蛹无影响。本文结果对应用PbGv防治菜粉蝶幼虫危害以及对该病毒的大量增殖均具指导意义。

EFFECT OF THE GRANULOSIS VIRUS FROM PIER1S BRASSICAE ON FEEDING, GROWTH AND DEVELOPMENT OF LARVAE OFARTOGEIA RAPAE

The larvae of Artogeia rafae, when fed with the granulosis virus from Pieris brassicae (PbGV) at the beginning of the first, second, third or fourth instar, would reduce their food consumption significantly. However, if the virus was fed at the end of fourth or the beginning of the fifth instar, the food consumption increased 36,3% or 87.2% respectively. The main cause for this difference is the change of the feeding period after virus infection.Ecdysis of diseased larvae was hampered before death; so the stadia in which they died were usually longer than that of the normal ones. Due to the prolongation of feeding period and the increase of food consumption, the larvae fed with PbGV at the end of the fourth in-star became much heavier than the healthy larvae and could reach a mean weight of 357.9 mg before death.When infected at young stage, the larvae usually could not pupate. However, 26.4% to 87.9% of the larvae infected on the first three days of the fifth instar could pupate, and no prohibitive effect on pupation was observed if PbGV was fed on the fourth day of this instar.