Nutrient supply and accessibility in plants: Effect of protein and carbohydrates on Australian plague locust (Chortoicetes terminifera) preference and performance

In contrast to predictions from nitrogen limitation theory, recent studies have shown that herbivorous migratory insects tend to be carbohydrate (not protein) limited, likely due to increased energy demands, leading them to preferentially feed on high carbohydrate plants. However, additional factors such as mechanical and chemical defenses can also influence host plant choice and nutrient accessibility. In this study, we investigated the effects of plant protein and carbohydrate availability on plant selection and performance for a migratory generalist herbivore, the Australian plague locust, Chortoicetes terminifera. We manipulated the protein and carbohydrate content of seedling wheat (Triticum aestivum L.) by two means: 1) we increased the protein:carbohydrate ratio using nitrogen (N) fertilizer, 2) we sought to increase carbohydrate accessibility by grinding cell walls after drying the plants. Using a full factorial design, we ran both choice and no-choice experiments to measure pre..., Plant treatment and nutrient analysis
Wheat treatments
We purchased seeds of red hard winter wheat (Triticum aestivum L.) from Sustainable Seed Company (South Salt Lake, Utah) and stored them in a freezer at -20°C until the beginning of the experiment. We chose this variety because of its hardiness and popular use as both a crop and as a dietary staple for lab-reared locust colonies. Wheat was grown hydroponically in a greenhouse at temperatures ranging from 20–22°C from November to January (light cycle 10.5 light hr:13.5 dark hr).
Seeds were first soaked for 18–24 hours in a cool dark area to initiate germination. We then placed 700–730 seeds in perforated containers (food-safe plastic, 16 x 13 x 4 cm) and covered them for two days. Once germinated, we placed those perforated containers in flood trays (Active Aqua AALR24B Low Rise Black Flood Table, ABS plastic, 121 x 61 x 13 cm). Every 8 hours, each tray was flooded for 15 minutes. Three days after being placed into the flood trays, u..., Microsoft Excel

与氮限制理论的预测相悖，近期研究表明迁飞草食性昆虫往往受碳水化合物（而非蛋白质）限制，这一现象大概率源于其能量需求提升，促使它们优先取食高碳水化合物植物。然而，机械防御与化学防御等额外因素同样会影响寄主植物选择及养分可获得性。
本研究针对广食性迁飞草食昆虫——澳大利亚灾蝗（Chortoicetes terminifera），探究了植物蛋白质与碳水化合物可获得性对其寄主选择与生长表现的影响。我们通过两种方式调控苗期小麦（Triticum aestivum L.）的营养组分：1）利用氮肥（N）提升蛋白质与碳水化合物的比值；2）先将植物烘干后研磨细胞壁，以提升碳水化合物的可及性。本研究采用全因子设计（full factorial design）开展选择与非选择实验，以测定…… 植物处理与养分分析
小麦处理
我们从美国犹他州南盐湖城的Sustainable Seed Company采购了硬红冬小麦（Triticum aestivum L.）种子，并于-20℃冷冻保存直至实验开始。该品种因抗逆性强，且既是大田作物又是实验室饲养蝗群的常用主食，故被选为实验材料。
我们于11月至次年1月在温室中水培种植小麦，温室温度维持在20~22℃，光照周期为10.5小时光照/13.5小时黑暗。
首先将种子置于阴凉黑暗环境中浸泡18~24小时以启动萌发。随后将700~730粒种子放入带孔的食品级塑料容器（16×13×4 cm）中，覆盖容器并静置2天。待种子萌发后，将带孔容器置于Active Aqua AALR24B低架黑色淹水台（Active Aqua AALR24B Low Rise Black Flood Table，ABS塑料材质，121×61×13 cm）中。每8小时对每个托盘淹水15分钟。将容器放入淹水台3天后，…… Microsoft Excel