Enhancement of the biological activity of nucleopolyhedrovirus through disruption of the peritrophic matrix of insect larvae by chlorfluazuron.
The enhancement of Spodoptera litura (F.) nucleopolyhedrovirus (SlNPV) activity using the chitin synthesis inhibitor chlorfluazuron was investigated. When tested against fifth-instar S. litura larvae, chlorfluazuron produced synergistic effects at doses of 0.05 and 0.025 microg per insect, and additive effects at doses of 0.1 and 0.2 microg. Furthermore, the time required for SlNPV to kill larvae was significantly reduced by chlorfluazuron at all doses tested. The activity and killing speed of Autographa californica (Spey) nucleopolyhedrovirus (AcMNPV) against third-instar Spodoptera exigua (Hübner) larvae were similarly improved by chlorfluazuron at a dose of 0.05 microg per larva. Furthermore, the growth of S. exigua was significantly retarded by chlorfluazuron. Environmental scanning electron microscopy (ESEM) showed that the peritrophic matrices (PMs) of S. litura exposed to chlorfluazuron alone, or the combination treatment, were markedly disrupted. Obvious ruptures on the outer surfaces of the PM were observed, which potentially facilitated the passage of virions through the matrix.
Guo
Hui-Fang
HF
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China. guohf@jaas.ac.cn
Fang
Ji-Chao
JC
Liu
Bao-Sheng
BS
Wang
Jie-Ping
JP
Zhong
Wan-Fang
WF
Wan
Fang-Hao
FH
D000818:Animals; D001835:Body Weight; D002686:Chitin / Q000037:antagonists & inhibitors; D007814:Larva; D017924:Nucleopolyhedroviruses; D010572:Pest Control, Biological / Q000379:methods*; D010671:Phenylurea Compounds; D011725:Pyridines; D018411:Spodoptera / Q000821:virology*
D010671:Phenylurea Compounds; D011725:Pyridines; D002686:Chitin; C057223:chlorfluazuron