Abstract：
Granuloviruses (GVs) Betabaculovirus associated with the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), especially those of the type I, have scarcely been studied. These GVs might be an effective alternative for the biocontrol of this insect. In this study, the native GVs SfGV-CH13 and SfGV-CH28 were isolated from FAW larvae and characterized for morphology, molecular traits, and insecticidal activity. The elapsed time between symptomatic infection of larvae and stop feeding as well as the weight of larvae before death or prior to pupation were also evaluated. Both GVs had ovoid shape and a length of 0.4 µm. They had the same DNA restriction profiles and their genome sizes were about 126 kb. The symptomatic infection with the tested GVs mainly caused flaccidity of larva body and discoloration of integument. The integument lysis was only observed in 8% of infected larvae. Infected larvae gradually stopped feeding. Overall, these symptoms are characteristic of infections caused by type I GVs, which are known as monoorganotropic or slow-killing GVs. The median lethal dose (LD50) values for SfGV-CH13 and SfGV-CH28 isolates were 5.4 × 102 and 1.1 × 103 OBs/larva, respectively. The median lethal time (LT50) ranged from 17 to 24 days. LT50 values decreased as the viral dose was increased. The elapsed time from symptomatic infection until pupation and body weight of larvae (third instar) were higher with SfGV-CH28 than SfGV-CH13. Both granulovirus isolates were able to kill the FAW larvae from the 12th day.
摘要：
与秋季粘虫（FAW）相关的颗粒病毒（GVs）Betabaculov，斜纹夜蛾（J.E.Smith）（鳞翅目：夜蛾科），尤其是那些I型的,几乎没有被研究过。这些GV可能是这种昆虫生物防治的有效替代品。在这项研究中,从FAW幼虫中分离出天然GVSfGV-CH13和SfGV-CH28，并进行了形态学表征，分子性状，和杀虫活性。还评估了幼虫有症状感染和停止进食之间的经过时间以及死亡前或化py前幼虫的重量。两个GV均为卵形，长度为0.4µm。它们具有相同的DNA限制性图谱,并且它们的基因组大小为约126kb。受试GV的症状性感染主要引起幼虫体松弛和外皮变色。仅在8％的感染幼虫中观察到被膜溶解。沾染的幼虫逐步停止摄食。总的来说,这些症状是由I型GV引起的感染的特征，它们被称为单亲性或慢杀灭性GVs。SfGV-CH13和SfGV-CH28分离株的中位致死剂量（LD50）值分别为5.4×102和1.1×103OBs/幼虫，分别。中位致死时间（LT50）为17至24天。LT50值随着病毒剂量的增加而降低。SfGV-CH28从症状感染到化page的经过时间和幼虫（第三龄）的体重高于SfGV-CH13。从第12天开始，两种颗粒病毒分离株都能够杀死FAW幼虫。
