Applied research on the Dendrolimus punctatus cytoplasmic polyhedrosis virus propagated in the substitute host Spodoptera exigua
Author of the article:ZHAO Zheng-Ping1** YAN Xue-Wu1*** WU Ying1 ZHOU Gang1 LIU Yue-Jin2
Author's Workplace:1. Hunan Academy of Forestry, Changsha 410004, China; 2. Hunan General Station of Forest Pest Management and Quarantine, Changsha 410004, China
Key Words: Dendrolimus punctatus, cytoplasmic polyhedrosis virus, the DpCPV compound agent, Spodoptera exigua, substitutive host, field management
Abstract:
[Objectives]
To provide a foundation for further research on the bio-control of Dendrolimus
punctatus in the field. The virulence of the Dendrolimus
punctatus cytoplasmic polyhedrosis virus (DpCPV) propagated in the
substitute host Spodoptera exigua, named Se-DpCPV, and its compound
agent, to D. punctatus, were studied. [Methods] The virulence of Se-DpCPV to D.
punctatus larvae was compared to that of the original isolate DpCPV by
feeding larvae pine needles infected with different concentrations of the
virus, and the virulence of Se-DpCPV to D. punctatus larvae of
different ages was determined. A field trial of the effectiveness of spraying
different concentrations of Se-DpCPV and its compound agents from a fixed-wing
unmanned aerial vehicle to control first generation of D. punctatus larvae
was also conducted. [Results]
Se-DpCPV was as infectious as the original isolate to 3rd instar larvae of D. punctatus and its median lethal concentration (LC50)
of 4.73×103 PIB/mL was not significantly different from that of the
original isolate (3.36×103 PIB/mL). Median lethal concentrations (LC50) of
Se-DpCPV against 2nd, 3rd, 4th and 5th instar larvae of D. punctatus were 2.03×103, 4.73×103,
1.05×104 and 3.85×104 PIB/mL, respectively. Spraying 3.75×1010, 7.50×1010 and 1.50×1011 PIB/hm2 Se-DpCPV mixed with 3.2% avermectin (7.5 mL/hm2) achieved corrected mortality
rates of D. punctatus of 86.05%, 90.70% and 94.19%, respectively. The
control efficiency of this mixture was significantly higher than that of 25%
chlorbenzuron (1 g/hm2), for which the corresponding corrected
mortality rates were 66.28%, 72.09% and 79.07%. Corrected mortality rates for
three different concentrations of Se-DpCPV applied without an insecticide were
59.30%, 63.95% and 70.93%. The infection rate of D. punctatus was 80.00%
to 93.33%. Compared with 3.2% avermectin and 25% chlorbenzuron, the control
efficiency of the Se-DpCPV mixture was at least 17.45% to 33.72% higher. [Conclusion] A mixture of Se-DpCPV (7.50×1010 PIB/hm2) and 3.2% avermectin (7.5 mL/hm2)
is recommended for the control of D. punctatus before the 3rd instar. This mixture can reduce the population base of D. punctatus within a short time and has a long-lasting effect.