Effect of juvenile hormone and pyriproxyfen treatments on the production of Spodoptera litura nuclear polyhedrosis virus

Efficient production is essential for developing baculoviruses into marketable bioinsecticides. In this study, we evaluated how juvenile hormone (JH) III and the JH analog pyriproxyfen affected the production efficiency of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) Nucleopolyhedrovirus (SpltNPV) in SpltNPV-inoculated early sixth instars. Both the JH III and pyriproxyfen treatments significantly enhanced the body size and weight of S. litura, which resulted in a 1.5- to 2-fold increase in the production of occlusion bodies (OBs). The OBs obtained from JH- and pyriproxyfen-treated larvae were as pathogenic as those produced in untreated larvae. More importantly, JH- or pyriproxy-fen-treated larvae consumed less than twice the amount of food consumed by two untreated larvae. These results indicate that JH and pyriproxyfen treatments improve the production efficiency of SpltNPV in S. litura. SpltNPV infection affected the development of S. litura not only as larvae, but also during subsequent growth stages and generations.