Behmer Spencer T, Joern Anthony
School of Biological Sciences, University of Nebraska, 68588-0118, Lincoln, NE, USA.
Oecologia. 1994 Jun;98(1):76-82. doi: 10.1007/BF00326093.
Diet selection based on the level of proline in an insect's host plant has been observed for a number of phytophagous insects, but few studies have examined potential differences in feeding preferences between males and females. The level of proline among an insect's host plants, particularly in drought-stressed plants, can be highly variable and often is positively correlated with soluble nitrogen levels. Additionally, proline is known to participate in a number of physiological functions in insects. We tested the effect of proline as a feeding stimulant in reproductively active grasshoppers using the graminivorous Ageneotettix deorum and the generalist, but mostly graminivorous, Phoetaliotes nebrascensis. Feeding preference tests using diets with representative free amino acid and sucrose levels but varying proline levels (zero, normal and 3 x normal) were examined. The feeding preference exhibited by both species was sex-specific, although the sex-specific response was more pronounced in P. nebrascensis than in A. deorum. Females of both species displayed preferences for diets high in proline. Males of neither species exhibited a preference for proline when responses were averaged over all treatment levels. However, within specific treatment combinations, male A. deorum preferred diets with high proline over diets with zero proline. These results suggest that diet selection for specific nutrients may vary between males and females because of differences in their physiological status and, possibly, differences in the nutritional requirements associated with reproduction. These results also suggest that subtle shifts in the concentration of individual nutrients within an insect's host plant may greatly influence insect feeding patterns.
对于许多植食性昆虫而言，基于其寄主植物中脯氨酸水平进行的饮食选择已被观察到，但很少有研究探讨雄性和雌性在取食偏好上的潜在差异。昆虫寄主植物中的脯氨酸水平，尤其是在干旱胁迫的植物中，可能变化很大，并且通常与可溶性氮水平呈正相关。此外，已知脯氨酸在昆虫的许多生理功能中发挥作用。我们使用食草性的德氏类飞蝗（Ageneotettix deorum）和多食性但主要食草的内布拉斯加光蝗（Phoetaliotes nebrascensis），测试了脯氨酸作为生殖活跃期蝗虫取食刺激物的效果。使用具有代表性的游离氨基酸和蔗糖水平但脯氨酸水平不同（零、正常和正常水平的3倍）的食物进行取食偏好测试。两个物种表现出的取食偏好都是性别特异性的，尽管性别特异性反应在内布拉斯加光蝗中比在德氏类飞蝗中更明显。两个物种的雌性都表现出对高脯氨酸食物的偏好。当对所有处理水平的反应进行平均时，两个物种的雄性都没有表现出对脯氨酸的偏好。然而，在特定的处理组合中，德氏类飞蝗的雄性更喜欢高脯氨酸食物而不是零脯氨酸食物。这些结果表明，由于雄性和雌性生理状态的差异以及可能与繁殖相关的营养需求差异，它们对特定营养物质的饮食选择可能有所不同。这些结果还表明，昆虫寄主植物中单个营养物质浓度的细微变化可能会极大地影响昆虫的取食模式。
