| Spodoptera litura(Fabricius)and Helicoverpa armigera(Hubner)are important worldwide pests that endanger tobacco,cotton and other crops.Both egg parasitoids and nuclear polyhedrosis virus are important biological factors for controlling S.litura and H.armigera,which greatly inhibit the population growth of two kinds of Spodoptera pests in nature.In this study,the morphological characteristics of SpltMNPV-T0 were systematically described,and the effects of SpltMNPV-T0 on the pathogenicity and fecundity of larvae and adults of S.litura and H.armigera in the 2nd,3rd and 4th instars were clarified,respectively.The control effects of mixed pairing of different nuclear polyhedrosis viruses on S.litura and H.armigera were carried out in the laboratory,and the control effects of different nuclear polyhedrosis viruses on S.litura egg—larva stage and the safety evaluation experiments of different S.litura nuclear polyhedrosis viruses combined with Trichogramma.The main results of this study are as follows:1.By scanning electron microscopy and transmission electron microscopy,the diameter of SpltMNPV-T0 polyhedra was 1.35 μm,and 1～12 nucleocapsids were coated in the envelope of each virus particle.2.At 26±1℃,the mortality rates of 1.0 × 107 PIB/mL SpltMNPV-T0 to different instars of S.litura and H.armigera decreased with the increase of instars.The corrected mortality rates of SpltMNPV-T0 to 2,3 and 4 instars of S.litura and H.armigera were 86.86%,81.35%,62.60%and 80.60%,74.81%,52.90%,respectively.SpltMNPVT0 significantly decreased the fecundity of female S.litura larvae,but SpltMNPV-T0 had no significant effect on the fecundity of females H.armigera larvae.SpltMNPVT0 had no significant difference in the longevity and hatching rate of female and male adults of S.litura and H.armigera.3.At 26±1℃,According to the final lethal rate,LT50 and ST results showed that,1.0×107 PIB/mL SpltMNPV-KY and SpltMNPV-T0 were mixed with 1.0×107 PIB/mL HaMNPV and SeMNPV,respectively,and the lethal rate of the third instar larvae of S.litura and H.armigera was the highest.According to the field control effect,the combination of SpltMNPV-T0+HaMNPV and SpltMNPV-KY+HaMNPV had the best control effect on S.litura and H.armigera,and the corrected control effects were 86.08%,88.46%and 76.24%,79.30%,respectively.4.At 26±1℃,SpltMNPV-KY+Trichogramma dendrolimi,SpltMNPV-KY+Trichogramma chilonis,SpltMNPV-T0+T.dendrolimi and SpltMNPV-T0+T.chilonis decreased the hatching rate of S.litura eggs by 46.8%,40.8%and 47.6%,42.4%,respectively,compared with 5%formaldehyde solution.However,SpltMNPV-KY alone had no significant effect on the hatching rate of S.litura eggs but had significant effects on the mortality of larvae and the probability of normal development in adults.The corrected mortality rates of larvae of SpltMNPV-KY and SpltMNPV-T0 combined with Trichogramma and SpltMNPV-KY and SpltMNPV-T0 alone were all greater than 60%,and the total mortality rates of eggs and larvae were all greater than 85%.SpltMNPV-KY,and SpltMNPV-T0 combined with Trichogramma had no significant effect on the parasitism rate and emergence rate of Trichogramma.Compared with the corresponding Trichogramma treatment group,the total mortality rates of SpltMNPVKY,SpltMNPV-T0 combined with Trichogramma pine caterpillar and Trichogramma stem borer increased by 10.8%,10.0%,and 11.6%,14.8%,respectively.The results showed that the combination of Trichogramma pine caterpillar and Trichogramma stem borer with nuclear polyhedrosis virus had a good control effect on the egg stage and larval stage of S.litura,and SpltMNPV-KY and SpltMNPV-T0 had no adverse effect on Trichogramma. |
PDF Full Text Request