重金属铅与害虫取食胁迫对小白菜和斜纹夜蛾的影响

Effects of heavy metal lead and herbivore feeding stress on pakchoi and Spodoptera litura(Lepidoptera:Noctuidae)

【目的】为探究重金属铅与害虫取食胁迫对小白菜Brassica chinensis营养物质、防御物质和斜纹夜蛾Spodoptera litura生长发育的影响。【方法】铅胁迫(400 mg/kg)、斜纹夜蛾幼虫取食处理(取食密度:3头/叶;取食面积:30%)以及二者共同胁迫后应用生物化学方法测定小白菜(品种为正旺达88)叶片中可溶性糖含量、胰蛋白酶抑制剂含量、铅含量以及保护酶(过氧化物酶、超氧化物歧化酶和过氧化氢酶)活性,并统计了斜纹夜蛾幼虫的存活率、幼虫历期、蛹历期、羽化率和成虫干重。【结果】400 mg/kg铅胁迫与斜纹夜蛾幼虫取食的联合作用显著影响了小白菜叶片中可溶性糖、胰蛋白酶抑制剂的含量以及过氧化物酶、过氧化氢酶和超氧化物歧化酶的活性;铅胁迫、斜纹夜蛾幼虫取食及二者共同胁迫对斜纹夜蛾幼虫存活率、幼虫历期、蛹历期、羽化率和成虫干重也有显著影响。与对照组相比,铅胁迫、斜纹夜蛾幼虫取食及二者共同胁迫下,小白菜叶片中可溶性糖含量有所下降,分别降低了10.5%,9.3%和38.1%;胰蛋白酶抑制剂含量分别增加了51.6%,90.1%和103.0%;过氧化物酶活性分别增加了136.1%,46.6%和243.8%;超氧化物歧化酶活性分别增加了43.1%,16.4%和91.1%;过氧化氢酶活性分别增加了68.6%,17.3%和139.0%。铅胁迫、斜纹夜蛾幼虫取食及二者共同胁迫下,斜纹夜蛾幼虫的存活率下降,与对照相比分别降低了28.2%,31.3%和43.9%;幼虫历期与对照相比分别延长了4.28,3.78和8.41 d;蛹历期与对照相比分别延长了2.69,2.13和5.11 d;羽化率下降,与对照相比分别降低了33.4%,46.7%和60.0%;成虫干重与对照相比分别降低了7.98,3.61和12.39 mg。【结论】结果说明铅胁迫、斜纹夜蛾取食以及二者共同胁迫对小白菜生长发育产生了不利影响,植物体内积聚的重金属铅能与斜纹夜蛾介导的植物化学防御产生叠加或协同效应,诱导小白菜的抗性增强,营养物质含量下降,进一步抑制斜纹夜蛾的生长发育。

【Aim】To explore the effects of heavy metal lead(Pb)and herbivore feeding stress on the nutrients and defense compounds in pakchoi(Brassica chinensis),and the growth and development of Spodoptera litura.【Methods】The plants of pakchoi variety Zhengwangda 88 were subjected to the stress of Pb(400 mg/kg),S.litura larval feeding(feeding density:3 individuals/leaf;feeding area:30%)and their combination,the contents of soluble sugar,trypsin protease inhibitor and Pb,and the activities of protective enzymes including peroxidase,superoxide dismutase and catalase in pakchoi leaves were detected using biochemical methods,and the larval survival rate,larval duration,pupal duration,emergence rate,and adult dry weight of S.litura were counted.【Results】The combined effects of 400 mg/kg Pb stress and S.litura larval feeding significantly affected the contents of soluble sugar and trypsin protease inhibitor,and the activities of peroxidase,catalase and superoxide dismutase in pakchoi leaves.The larval survival rate,larval duration,pupal duration,emergence rate,and adult dry weight were also significantly affected by Pb stress,S.litura larval feeding,and their combinations.Compared with the control group,Pb stress,S.litura larval feeding,and their combinations decreased the soluble sugar contents in pakchoi leaves by 10.5%,9.3%and 38.1%,respectively,and increased the trypsin protease inhibitor contents by 51.6%,90.1%and 103.0%,respectively;and increased the peroxidase activities by 136.1%,46.6%and 243.8%,respectively,the superoxide dismutase activities by 43.1%,16.4%and 91.1%,respectively,and the catalase activities by 68.6%,17.3%and 139.0%,respectively.In addition,Pb stress,S.litura larval feeding,and their combinations decreased the larval survival rates of S.litura by 28.2%,31.3%and 43.9%,respectively;extended the larval duration by 4.28,3.78 and 8.41 d,respectively,and the pupal duration by 2.69,2.13 and 5.11 d,respectively;and decreased the emergence rates by 33.4%,46.7%and 60.0%,respectively,and the adult dry weight by 7.98,3.61 and 12.39 mg,respectively,compared to the control group.【Conclusion】The results suggest that Pb stress,S.litura larval feeding and their combinations have negative effects on the growth and development of pakchoi.The accumulation of heavy metal Pb in pakchoi plants can produce a superposition or synergistic effect on the phytochemical defense mediated by S.litura,inducing the pakchoi resistance to increase and nutrient content to decrease,and further inhibiting the growth and development of S.litura.