Competition among three entomopathogenic viruses in larvae of the smaller tea tortrix, Adoxophyes sp.

测定了筑波某茶田扁蝽幼虫种群中病毒性疾病的流行情况。从死亡的幼虫中分离出3种昆虫病原病毒，分别为核多角体病毒（NPV）、虫痘病毒（EPV）和颗粒病病毒（GV）。EPV是最常见的病毒，占粘虫幼虫死亡的23.1%。超过25%的幼虫同时感染两种或两种以上的病毒。在实验室条件下，研究了小茶虻幼虫中NPV与EPV或GV的竞争。当粘虫4龄幼虫感染NPV后，第5天开始产生子代病毒孵育体。当棘球绦虫4龄幼虫感染EPV后，在感染后第10天开始产生子代病毒掩蔽体。然而，当Adoxophyes sp . 4龄幼虫同时感染NPV和EPV时，没有产生EPV的病毒闭塞体。这些数据表明，NPV在三种昆虫病原病毒中具有最强的竞争能力。三种病毒之间竞争能力的差异似乎源于这些病毒内在自然增长率值的不同。

The prevalence of viral diseases in a larval population of Adxophyes sp. in a tea field in Tsukuba was determined. Three entomopathogenic viruses, a nucleopolyhedrovirus (NPV), an entomopoxvirus (EPV) and a granulosis virus (GV) were isolated from the dead larvae. The EPV was the most common virus and was responsible for 23.1% of the deaths in the Adoxophyes sp. larvae . More than 25% of larvae were infected with two or more of the viruses simultaneously.Competitions between NPV and EPV or GV in larvae of the smaller tea tortrix, Adoxophyes sp. were investigated under a laboratory condition. When the fourth instar larvae of Adoxophyes sp, were infected with NPV,progeny viral oculusion bodies began to produce at day 5 post infection. When the fourth instar larvae of Adoxophyes sp. were infected with EPV,progeny viral occulusion bodies began to produce at day 10 post infection. However, no viral occlusion bodies of EPV were produced when the fourth instar larvae of Adoxophyes sp, were simultaneously infected with NPV and EPV.These data suggested that NPV had the most competitive ability among three entomopathogenic viruses. Difference in competitive ability among three viruses seems to originate from difference in values of the intrinsic rate of natural increase of these viruses.