Jiang Dun, Di Gui Qiu, Yan Shan Chun
College of Forestry, Northeast Forestry University, Harbin 150040, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jun;29(6):1969-1974. doi: 10.13287/j.1001-9332.201806.039.
To investigate the eco-physiological responses of phytophagous insects to host plants exposed to heavy metal stress, the gypsy moth (Lymantria dispar) larvae were reared with leaves of Populus albaXP. berolinensis grown in Cd-contaminated soil to analyze their food utilization and mechanisms underlying Cd excretion. Our results showed that after feeding on Cd-stressed poplar leaves, Cd concentrations and contents in the 3rd-6th instar larvae were significantly higher than those in control. The Cd concentrations significantly decreased with the larval age, whereas it was reverse for Cd contents. Cd concentrations in the larval faces and exuvia were significantly higher than those in control. Food digestion/consumption rate and conversion rate of the 3rd-5th instar larvae in the Cd-treatment group were significantly higher and lower than those in the control, respectively. Food utilization rate of the Cd-stressed 3rd-4th instar larvae were not significantly different from that of the control larvae with the same age. In contrast, the Cd-stressed 5th instar larvae showed a significantly lower food utilization rate than the control. These results indicated that gypsy moth larvae could remove some Cd from their bodies through effective excretion (e.g. feces and exuvia), with the mature larvae being more effective than the juveniles. The increases of larval body mass seemed to have a "dilution effect" on its Cd concentration. Under Cd stress, the gypsy moth larvae might maintain a certain level of food utilization rate for growth and development via a modulation of food consumption/conversion rates, but Cd-stress would still reduce the larval food utilization rate when it was beyond a certain threshold.
为了研究植食性昆虫对暴露于重金属胁迫下的寄主植物的生态生理响应，用生长在镉污染土壤中的银白杨×小叶杨叶片饲养舞毒蛾幼虫，以分析它们的食物利用情况和镉排泄的潜在机制。我们的结果表明，取食镉胁迫的杨树叶片后，3至6龄幼虫体内的镉浓度和含量显著高于对照组。镉浓度随幼虫龄期显著降低，而镉含量则相反。幼虫粪便和蜕壳中的镉浓度显著高于对照组。镉处理组3至5龄幼虫的食物消化/消耗率显著高于对照组，而转化率则显著低于对照组。镉胁迫的3至4龄幼虫的食物利用率与同龄对照幼虫无显著差异。相比之下，镉胁迫的5龄幼虫的食物利用率显著低于对照组。这些结果表明，舞毒蛾幼虫可以通过有效的排泄（如粪便和蜕壳）从体内排出一些镉，成熟幼虫比幼虫更有效。幼虫体重的增加似乎对其镉浓度有“稀释作用”。在镉胁迫下，舞毒蛾幼虫可能通过调节食物消耗/转化率来维持一定水平的食物利用率以促进生长发育，但当镉胁迫超过一定阈值时，仍会降低幼虫的食物利用率。
