β-蜕皮激素对异色瓢虫羧酸酯酶基因表达及酶活性影响的初步研究

Preliminary study on the effects of ecdysterone on CarE mRNA expression and carboxylesterase activity of Harmonia axyridis (Coleoptera:Coccinellidae)

为了探明β-蜕皮激素对异色瓢虫的作用及其安全剂量,本研究利用实时定量PCR(RT-PCR)和比色法测定了异色瓢虫3龄幼虫施用不同浓度的β-蜕皮激素体内羧酸酯酶活性与基因表达情况。结果表明:用0.1、0.5、1mg/Lβ-蜕皮激素处理异色瓢虫3龄幼虫,在处理后4～48h内CarE mRNA水平和CarE比活力呈现先升高、保持正常水平或略下降、再升高、然后很快恢复正常的规律。到处理后的第48h,处理组的CarE mRNA表达量和CarE比活力均恢复到正常水平。所以,认为在低于1mg/L浓度下应用β-蜕皮激素控制害虫对异色瓢虫的3龄幼虫安全。而利用5mg/L或10mg/L的β-蜕皮激素处理异色瓢虫3龄幼虫,CarE mRNA表达量和CarE比活力均表现出长期的被抑制效应,特别是到处理24h后,CarE mRNA表达量和CarE活性不仅未能恢复到正常水平,反而一直处于极低的水平。因此,认为这两个浓度对异色瓢虫3龄幼虫不安全。

In order to find out the effects of ecdysterone on Harmonia axyridis （Pallas） （Coleoptera.. Coccinelli- dae） and its safety dose, the RT-PCR and colorimetry methods were used to determine the effects of ecdysterone on Care mRNA expression and carboxylesterase activity of the 3rd instar larvae of H. axyridis. The results showed that Care mRNA expression and carboxylesterase activity of the treated larvae showed a regular pattern from 4 h to 48 h after treated with 0.1 mg/L, 0.5 mg/L and 1 mg/L ecdysterone, which increased first, returned to and maintained at normal level or decreased slightly, then increased again and finally returned to the normal level again quickly. At 48 h after treatment, all CarE mRNA expression and carboxylesterase activity of the trea- ted group returned to normal level. It suggested that 1 mg/L or lower concentration of ecdysterone was safe to the third instar larvae of H. axyridis. But if the third instar larvae of H. axyridis was treated with 5 mg/L or 10 mg/L ecdysterone, Care mRNA expression and carboxylesterase activity showed a long-term inhibition effect, especially at 24 h and later after treatment. CarE mRNA expression and carboxylesterase activity not only did not return to the normal level, but maintained at very low level all the time, indicating that these two concentrations were un- safe to the third instar larvae of H. axyridis.