Effect Of Immune Challenge On Locusta Migratoria Vitellogenin Occurred

This paper used Locusta migratoria manilensis (Meyen) as research object. It studied the changes of expression in vitellogenin and related genes of juvenile hormone and vitellogenin receptor of female fat body and ovarty, based on injection of different concentrations of dextran microspheres Sephadex G-50 and infection with different concentrations of Micrococcus luteus in locust adults of different periods. Besides, combined with the change of locust phenoloxidase activity under different concentrations of simulate parasitic treatment, the author studied effect of immune challenge on locust vitellogenin occurred, discussed how to strike a balance between immunity and reproduction with the limited resources. The results are shown as follow:1. This paper showed the changes of expression in Vg and VgR and JH after injected different concentrations of dextran microspheres artificially. The results showed that when the injection concentration reached 50 mg/mL, the expression of three genes was increased relative to the control group of female locust ovary at sexual maturity period and mating period, while it was decreased at oviposition period. Furthermore, the expression of three genes of oviposition period was extremely significant decreased relative to sexual maturity period and mating period. Moreover, the expression of Vg of fat body was the same as the expression of ovary. And the expression of JH was significantly decreased at sexual maturity period and oviposition period, while it was significantly increased at mating period. The expression of VgR was significantly or extremely significant increased at sexual maturity period, besides, one of the two VgR was significantly decreased at mating period and oviposition period, but the other one was no significant change at mating period and oviposition period.2. The experiment of injecting different concentrations of dextran microspheres artificially also showed that the phenoloxidase activity was significantly decreased relative to the control group at the concentration of 50 mg/mL at sexual maturity period and mating period of female locust. Then the phenoloxidase activity of oviposition period was increased relative to the control group after injecting different concentrations of dextran microspheres, which was increased along with the concentrations of dextran microspheres. The results also indicated that compared with sexual maturity period and mating period, the phenoloxidase activity of oviposition period was significantly or extremely significant increased.3. This paper studied the changes of expression in vitellogenin after infected different concentrations of Micrococcus luteus artificially. The results indicated that when the infection concentration reached 0.6 or 0.9, the expression of Vg was decreased relative to the control group of female locust ovary and fat body at sexual maturity period and fat body at mating period, while it was increased in ovary at oviposition period, and the expression of Vg of oviposition period was significantly or extremely significant increased relative to sexual maturity period and mating period in fat body. When the infection at a concentration of 0.1 or 0.3, the expression of Vg was increased in ovary at mating period and in ovary and fat body at oviposition period. In addition, the expression of Vg of oviposition period was significantly or extremely significant increased relative to sexual maturity period and mating period in ovary and fat body.4. The experiment of infecting different concentrations of Micrococcus luteus artificially also displayed that when the infection at a concentration of 0.9, the phenoloxidase activity was increased relative to the control group at sexual maturity period of female locust, while it was decreased at mating period, but there was no significant change at oviposition period. Meanwhile, the phenoloxidase activity was increased along with the infection concentrations of Micrococcus luteus at sexual maturity period and oviposition period. It also indicated that the phenoloxidase activity of oviposition period was significantly increased relative to sexual maturity period and mating period in the control group, and phenoloxidase activity was the lowest at mating period.5. This study investigated the changes of expression in JH and VgR after infected different concentrations of Micrococcus luteus artificially. The results indicated that when the infection at a concentration of 0.3 or 0.6 or 0.9, the expression changes of JH was extremely significant increased at sexual maturity period and mating period in fat body and ovary, while it was significantly decreased in ovary at oviposition. And when the infection concentration reached 0.9, the expression changes of JH was significantly decreased at oviposition in fat body. When the infection at a concentration of 0.1 or 0.3, the the expression changes of VgR was increased at oviposition period. In fat body, when the infection concentration reached 0.9, the the expression changes of VgR was decreased at mating period, and at sexual maturity period, one of VgR was increased, the other was decreased. In ovary, when the infection concentration reached 0.9, the expression changes of VgR was significantly decreased at sexual maturity period, but at mating period and oviposition period, one of VgR was significantly decreased, the other was no no significant change.The results indicated that the immune challenge had great influence on locust vitellogenin occurrence, and different immune challenges had different effects. Therefore, the study on how to balance between immunity and reproduction when the locust encountered immune challenge could lay a theoretical foundation as to seek new ways of locust biocontrol.