Studies On Synergism Of Several Synergistic Factors To Insect Viral Enhancement

Pesticides of Nucleopolyhedrovirus and Granulovirus was used to control Spodoptera litura, Pieris rapae and Plutella xylostella in the field. This paper presented the research about insecticides synergists. We improved its synergy effect by mixing chemicals and insect baculovirus or mixing NPV and GV. This paper discussed synergistic effect and the mechanism.The results of the synergistic effect were as follows:(1) Fourth-instar larvae of Spodoptera litura were fed on artificial diet mixed with combinations of Spodoptera litura Nuclear Polyhedron Virus(SlNPV) and chemical insecticides including chlorpyrifos and chlorfenapyr under 28℃ .Mortalities were observed, LC₅₀, LT50 values and synergic ratio were determined. The results showed that SINPV mixed with chemical insecticides can coordinate with each other and enhance the last mortalities. When we add 10% normal use of chemical insecticides to SINPV,the synergic ratio is 1194.09 and 661.40 at the seventh day, LT₅₀is shortened by 2.319-2.916 days. When we added SINPV of 5×10⁶PIB/mL to chemical insecticides, the synergic ratio is 2.75 and 2 at the fifth day .(2) Third-instar larvae of Pieris rapae were infected in combinations of the Nucleopolyhedrovirus of Anagrapha falcifera Multiple(AfNPV) and Pieris rapae Granulosis(PrGV) under 20-22 ℃. The synergic ratio of PrGV and AfNPV is over 600 and 400. The LT50 of the virus mixture were shorter than AfNPV and PrGV for 1.10 2.06d and 0.40-1.93d.(3) Pesticides of PrGV, AfNPV and the mixture were used to control Pieris rapae and Plutella xylostella in the field. The results showed that both PrGV and AfNPV had high effects against Pieris rapae, which were over 93% at the 15th day after treatment. AfNPV and the mixture of PrGV and AfNPV were also with high effects against Plutella xylostella, the average control effects were over 89% at the 15th day after treatment. In addition, both pesticides had higher effects than those of chlorpyrifos treatment against Pieris rapae and Plutella xylostella, which were 88% and 84% respectively.(4) Fourth-instar larvae of Spodoptera litura were fed on artificial diet mixed with combinations of SINPV, PrGV and the mixture under 28 ℃. The results showed that PrGV had no effect against Spodoptera litura. The synergic ratio of SINPV and PrGV is 24.46 comparing to SINPV. The death ratio was not enhanced obviously. So there was no obvious synergistic effect.