The Impact Of HMGR On Growth, Development And Reproduction In German Cockroach

A reductase (HMGR),3-hydroxy-3-methylglutaryl coenzyme is the key enzyme of the mevalonate pathway (MVA). MVA is the upstream process of juvenile hormone (JH) synthesis. MVA and JH play a very important role in the growth, development and reproduction of insects. The HMGR inhibitors and the technique of RNA interference are the potential methods of pest management. In order to address many question of basis of MVA adjustment and JH synthesis. On the other hand, we are also interested in establishing the appliance of HMGR inhibitor and RNA interference in pest management. The German cockroach, Blattella germanica Linnaeus, as used as the model, HMGR inhibitor is used to inhibit HMGR protein in nymph, RNAi technique is used to silence the HMGR expression in females, the impact of HMGR gene on growth and fecundity is studied. The main results are as follows:After the HMGR inhibitor inhibiting the HMGR protein in 1 day old nymph, the mortality rate increased and growth and development were inhibited. The inhibitions of growth and development were indicated by the decrease in increase rate of body weight and prolongation of development duration. The extent of increase in mortality and growth and development was negatively related with instars treated. The extent of increase in mortality and growth and development was positively related with dosage of inhibitor. There were two peaks in mortality rate when the nymph was at 2 days old (when the nymph was treated with the inhibitor) and 7 days old. Treatment of juvenile hormone analog reduced the mortality rate and abated the impact of HMGR on growth and development.After the HMGR inhibitor inhibiting the HMGR protein in final-instar nymph, the growth and development was inhibited. These were indicated by the decrease in increase rate of body weight and delay in eclosion. The extent of decrease in development was positively correlated with the concentration of the inhibitor. Treatment of juvenile hormone analog abated the impact of HMGR on growth and development.Double-stranded RNA (dsRNA) was synthesized for the HMGR gene in German cockroach.This dsRNA in different concentration were injected into B. germanica. The high concentration treatment showed that the development of ovary was inhibited.0.2μg this dsRNA treatment is the critical concentration. The length of oocyte is statistical significant difference with the control. The length of oocyte is 37.62% of the control. The length of oocyte of 0.02μg this dsRNA treatment is statistical significant difference with the control. The length of oocyte is 80.32% of the control. The length of oocyte of 0.02μg this dsRNA treatment is no statistical significant difference with the control.This dsRNA in different concentration were injected into B. germanica. The high concentration treatment showed that the development of accessory glant was inhibited. 0.2μg this dsRNA treatment is the critical concentration. The width of the tubes of accessory gland is statistical significant difference with the control. The width of the tubes of accessory gland is 54.52% of the control. The width of the tubes of accessory gland of 0.02μg this dsRNA treatment is no statistical significant difference with the control.This dsRNA in different concentration were injected into B. germanica. The high concentration treatment caused sterile in female adult.0.2μg this dsRNA treatment is the critical concentration. The females of this treatment did not form the first ootheca.40% of the females of the 0.02μg dsRNA treatment formed the first ootheca. All of the females of the 0.002μg dsRNA treatment and control formed the first ootheca.