STUDIES ON THE EFFECT OF TRICHOGRAMMA CARRYING NPV TO SUPPRESS HELICOVERPA ARMIGERA

Releasing Trichogramma carrying NPV to suppress the second, third and fourth generations of H. armigera, chemical control field was treated by pesticide. Results showed that the average parasitism rate of Trichogramma to the eggs of H. armigera in the releasedg Trchogramma field was 33. 3% , the utmost was 37. 3% . The infect death rate of H. armigera by NPV was from 61. 3% to 70. 6% . Natural enemies including Coccinellids、Arane and Orius similis in the released Trichogramma field, which average quantity per hundred plants were 83. 6% , 100. 8% and 69. 2% more than those of the chemical control field respectively. Chrysopa, and Reduvii, the kinds of natural preying enemies, could be found in the released Trichogramma field, butcould not be found in the control field. The average decrease rate of the population density of H. armigera in the released Trichogramma field was 66. 1 %, that of the chemical control field was 70. 25 % , the difference of them was not significant. The average damage rate of the flower bud in the released Trichogramma field were close to that in the chemical control field.