Jeong Se Jong, Nam Bo Eun, Jeong Hyeon Jin, Jang Jae Yeon, Joo Youngsung, Kim Jae Geun
Department of Biology Education, Seoul National University, Seoul, Republic of Korea.
Research Institute of Basic Sciences, Seoul National University, Seoul, Republic of Korea.
Front Plant Sci. 2023 May 30;14:1145363. doi: 10.3389/fpls.2023.1145363. eCollection 2023.
Plants need to balance investments in growth and defense throughout their life to increase their fitness. To optimize fitness, levels of defense against herbivores in perennial plants may vary according to plant age and season. However, secondary plant metabolites often have a detrimental effect on generalist herbivores, while many specialists have developed resistance to them. Therefore, varying levels of defensive secondary metabolites depending on plant age and season may have different effects on the performance of specialist and generalist herbivores colonizing the same host plants. In this study, we analyzed concentrations of defensive secondary metabolites (aristolochic acids) and the nutritional value (C/N ratios) of 1-, 2- and 3-year in July (the middle of growing season) and September (the end of growing season). We further assessed their effects on the performances of the specialist herbivore (Lepidoptera: Papilionidae) and the generalist herbivore (Lepidoptera: Noctuidae). Leaves of 1-year contained significantly higher concentrations of aristolochic acids than those of older plants, with concentrations tending to decrease over the first-year season. Therefore, when first year leaves were fed in July, all larvae of died and showed the lowest growth rate compared to older leaves fed in July. However, the nutritional quality of leaves was lower in September than July irrespective of plant age, which was reflected in lower larval performance of both herbivores in September. These results suggest that invests in the chemical defenses of leaves especially at a young age, while the low nutritional value of leaves seems to limit the performance of leaf-chewing herbivores at the end of the season, regardless of plant age.
植物在其一生中需要平衡生长和防御方面的投入，以提高自身的适合度。为了优化适合度，多年生植物对食草动物的防御水平可能会根据植物年龄和季节而有所不同。然而，植物次生代谢产物通常会对广食性食草动物产生不利影响，而许多专食性食草动物已对它们产生了抗性。因此，根据植物年龄和季节变化的防御性次生代谢产物水平，可能会对寄生于同一寄主植物上的专食性和广食性食草动物的表现产生不同影响。在本研究中，我们分析了7月（生长季节中期）和9月（生长季节末期）1年生、2年生和3年生[植物名称未明确给出]的防御性次生代谢产物（马兜铃酸）浓度和营养价值（碳氮比）。我们进一步评估了它们对专食性食草动物（鳞翅目：凤蝶科）和广食性食草动物（鳞翅目：夜蛾科）表现的影响。1年生[植物名称未明确给出]的叶片中马兜铃酸浓度显著高于 older plants（此处原文表述有误，推测应为老植株），且浓度在第一年的季节中呈下降趋势。因此，当在7月喂食第一年的叶片时，[某种蝴蝶名称未明确给出]的所有幼虫死亡，并且与7月喂食老叶片相比，[另一种蝴蝶名称未明确给出]显示出最低的生长速率。然而，无论植物年龄如何，9月时[植物名称未明确给出]叶片的营养质量均低于7月，这反映在两种食草动物9月的幼虫表现较低。这些结果表明，[植物名称未明确给出]尤其在幼龄时会投入叶片的化学防御，而叶片的低营养价值似乎在季节末期限制了咀嚼式食草动物的表现，无论植物年龄如何。
