Johnson Haley, Solensky Michelle J, Satterfield Dara A, Davis Andrew K
Biology Department, University of Jamestown, Jamestown, North Dakota, United States of America.
Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America.
PLoS One. 2014 Apr 2;9(4):e93492. doi: 10.1371/journal.pone.0093492. eCollection 2014.
In animals with complex life cycles, all resources needed to form adult tissues are procured at the larval stage. For butterflies, the proper development of wings involves synthesizing tissue during metamorphosis based on the raw materials obtained by larvae. Similarly, manufacture of pigment for wing scales also requires resources acquired by larvae. We conducted an experiment to test the effects of food deprivation in the larval stage on multiple measures of adult wing morphology and coloration of monarch butterflies (Danaus plexippus), a species in which long-distance migration makes flight efficiency critical. In a captive setting, we restricted food (milkweed) from late-stage larvae for either 24 hrs or 48 hrs, then after metamorphosis we used image analysis methods to measure forewing surface area and elongation (length/width), which are both important for migration. We also measured the brightness of orange pigment and the intensity of black on the wing. There were correlations between several wing features, including an unexpected association between wing elongation and melanism, which will require further study to fully understand. The clearest effect of food restriction was a reduction in adult wing size in the high stress group (by approximately 2%). Patterns observed for other wing traits were ambiguous: monarchs in the low stress group (but not the high) had less elongated and paler orange pigmentation. There was no effect on wing melanism. Although some patterns obtained in this study were unclear, our results concerning wing size have direct bearing on the monarch migration. We show that if milkweed is limited for monarch larvae, their wings become stunted, which could ultimately result in lower migration success.
在具有复杂生命周期的动物中，形成成体组织所需的所有资源都是在幼虫阶段获取的。对于蝴蝶来说，翅膀的正常发育涉及在变态过程中根据幼虫获取的原材料合成组织。同样，翅膀鳞片色素的制造也需要幼虫获取的资源。我们进行了一项实验，以测试幼虫阶段食物剥夺对帝王蝶（黑脉金斑蝶）成虫翅膀形态和颜色的多种测量指标的影响，帝王蝶是一种长途迁徙使飞行效率至关重要的物种。在圈养环境中，我们对晚期幼虫限制食物（乳草）24小时或48小时，然后在变态后，我们使用图像分析方法测量前翅表面积和伸长率（长度/宽度），这两者对迁徙都很重要。我们还测量了橙色色素的亮度和翅膀上黑色的强度。几个翅膀特征之间存在相关性，包括翅膀伸长率和黑化之间意想不到的关联，这需要进一步研究才能完全理解。食物限制最明显的影响是高压力组成虫翅膀尺寸减小（约2%）。观察到的其他翅膀特征的模式不明确：低压力组（但不是高压力组）的帝王蝶翅膀伸长率较低，橙色色素较淡。对翅膀黑化没有影响。尽管本研究中获得的一些模式不明确，但我们关于翅膀尺寸的结果与帝王蝶迁徙直接相关。我们表明，如果帝王蝶幼虫的乳草有限，它们的翅膀会发育不良，这最终可能导致迁徙成功率降低。
