Abstract:
Objective To study the effects of exogenous juvenile hormone analogue (JHA) on Chinese white wax scale with focus on wax secretion and development.
Method High, medium and low concentrations of JHA were sprayed on the second-instar male scale, smeared on and injected in the stem of host tree respectively.
Result The results of test showed that spraying the male second-instar with medium concentration of JHA (2.5 mg·mL-1) can significantly improve the wax secretion of Chinese white wax scale (Ericerus pela), the average production rate in Kunming region reached 41.50%, the average production rate in Emei region reached 25.56%. However, the experimental results show difference between the 2 regions, the reason may be related to the difference of ecological environment in the two areas. For the effects of JHA on pupal development of E. pela, medium and low concentration JHA can promote the weight of pupa, but high concentration showed inhibition; the inhibition of JHA on pupal length was enhanced with the increase of JHA concentration. JHA can promote pupae eclosion, the eclosion rate could reach as high as 62.70%-81.62%.
Conclusion The treatment of 2nd instar male larvae with medium concentration of JHA could significantly increase the wax secretion of E. pela. There is a negative correlation between the length of pupa and JHA concentration in the E. pela. The body weight of E. pela pupae showed low concentration promotion and high concentration inhibition; Under spraying and smearing treatments, high concentration can significantly increase the emergence rate of E. pela pupae. The emergence of E. pela pupae is not influenced by its body weight and body length.