ABSTRACT

In vivo production of baculoviruses requires optimisation studies for each host-virus system. Considering the potential of a Mexican isolate of Spodoptera exigua multiple nucleopolyhedrovirus (SeSIN6) for developing a biopesticide, here, a compartmentalised tray system and a cool-textured diet were used to determine the effect of incubation temperature on the pathogenicity, speed of kill, and production of occlusion bodies (OBs). All measurements were compared with a characterised American nucleopolyhedrovirus isolate (SeUS2). Incubation of fourth instar S. exigua at 20, 25, and 30°C did not significantly affect the mortality caused by either isolate, although a delay in virus infection was observed at 20°C. The OB production of both isolates in infected larvae was significantly lower at 20°C than at 25 and 30°C. At all temperatures, the OB production of the SeSIN6 isolate was higher than the SeUS2 isolate. The production of OBs per mg larva was significantly higher at 30°C for both isolates. A positive correlation was observed between larval weight gain and the production of OBs/larva at all temperatures, whereas a negative correlation was observed between larval gain weight and OBs/mg of larval weight in most of the treatments. We conclude that incubation temperatures of 25 and 30°C are optimal for OB production per larva in both isolates tested. Further studies are needed to examine other factors that can improve the production of Mexican SeMNPV isolates.

摘要

杆状病毒的体内生产需要对每个宿主病毒系统进行优化研究。考虑到墨西哥分离株 Spodoptera exigua 多核多角体病毒 (SeSIN6) 用于开发生物杀虫剂的潜力，在这里，使用分隔托盘系统和凉爽质地的饮食来确定孵化温度对致病性、杀灭速度和闭塞体（OB）的产生。将所有测量值与特征的美国核多角体病毒分离物 (SeUS2) 进行比较。四龄S. exigua的孵化尽管在 20°C 时观察到病毒感染延迟，但在 20°C、25°C 和 30°C 时对任一分离株造成的死亡率没有显着影响。两种分离株在受感染幼虫中的 OB 产量在 20°C 时显着低于在 25°C 和 30°C 时。在所有温度下，SeSIN6 分离物的 OB 产量均高于 SeUS2 分离物。两种分离株在 30°C 时每毫克幼虫的 OB 产量显着更高。在所有温度下，幼虫增重与 OBs/幼虫的产生呈正相关，而在大多数处理中，幼虫增重与 OBs/mg 幼虫体重之间存在负相关。我们得出结论，25 和 30°C 的孵化温度对于测试的两种分离株中每只幼虫的 OB 生产是最佳的。