Abstract:

 Cnaphalocrocis medinalis granulovirus, CnmeGV, is a specific pathogenic baculovirus of rice pest Cnaphalocrocis medinalis. The objective of this study is to analyze the sub-lethal effects of CnemGV to the growth, reproduction and physiology of C. medinalis, to provide a theoretical basis for the application of baculovirus for pest control. CnmeGV was still detected in the survival larvae 10 days later after 3^rd instar larvae of C. medinalis treated with sub-lethal dose of CnmeGV at high frequency, resulting in sub-lethal effect to C. medinalis. Sub-lethal treatment of CnmeGV did great impaction on the development of C. medinalis, especially in the metamorphosis process of pupation, eclosion, and oviposition. The pupa weight decreased by 15.95%, eclosion rate reduced by 24.81%, oviposition dropped by 41.5%, significantly different from that of control. The ratio of female to male also declined from 1.11 to 0.82. Sub-lethal effect of CnmeGV enhanced the energy metabolism of larvae, with the actives of amylase and lipase raised remarkably. Among detoxifying enzymes, the active of GST was improved, while ACT level dropped significantly compared to that of control. Sub-lethal of CnmeGV influenced the secretion of hormones. The levels of juvenile and molting hormone declined by 5.62 and 4.59 folds respectively. Vitellogenin content of females was detected to reduce about 40.63% in the sub-lethal treatment. This might affect the oviposition rate of adults.

Key words:

Cnaphalocrocis medinalis; granulovirus, sub-lethal effect, development and reproduction