Showler Allan T, Moran Patrick J
Integrated Farming and Natural Resources Research Unit, Kika de la Garza Subtropical Agricultural Research Center, USDA-ARS SARC, 2412 East Highway 83, Weslaco, Texas 78596, USA.
J Chem Ecol. 2003 Sep;29(9):1997-2011. doi: 10.1023/a:1025626200254.
The beet armyworm, Spodoptera exigua (Hübner), has been anecdotally reported to oviposit more on drought stressed than on nonstressed cotton plants. Using potted cotton plants in cages, this study demonstrated that beet armyworms deposited 3.3, 4.6, and 2.3 times more (P < or = 0.05) eggs on cotton plants that were grown on 1500, 1000, and 750 ml water/wk, respectively, than on cotton plants grown in well watered (4000 ml water/wk) soil. Third instars, however, showed no preference for stressed cotton foliage over nonstressed foliage. Third instar beet armyworms raised on well watered cotton plants were 1.5, 2.3, and 2.6 times heavier than those reared on cotton grown in the 1500, 1000, and 750 ml water/wk plants (P < or = 0.05), respectively. Physiochemical analyses showed that drought stressed leaves had significantly greater accumulations of free amino acids that are essential for insect growth and development. Soluble protein and soluble carbohydrates were also more abundant in stressed leaves compared to nonstressed leaves. Despite the apparent increase in nutritional quality in drought stressed plants, larval survival was reduced, probably because the limiting factor became water. Greater amounts of cotton leaf area were consumed from drought stressed leaves (P < or = 0.05) than from nonstressed leaves, probably because the larvae had to metabolize greater portions of assimilated energy to supplement body water with metabolic water derived from respiration. The association of greater host plant nutritional quality to oviposition preference, and conversely, to reduced survivorship, is discussed.
据传闻，甜菜夜蛾（Spodoptera exigua (Hübner)）在干旱胁迫的棉花植株上比在未受胁迫的棉花植株上产卵更多。本研究利用笼中的盆栽棉花植株证明，甜菜夜蛾在每周分别浇灌1500、1000和750毫升水的棉花植株上产的卵，比在每周浇灌4000毫升水（充分浇水）的土壤中生长的棉花植株上多3.3倍、4.6倍和2.3倍（P≤0.05）。然而，三龄幼虫对胁迫棉花叶片和未胁迫叶片没有偏好。在充分浇水的棉花植株上饲养的三龄甜菜夜蛾，分别比在每周浇灌1500、1000和750毫升水的棉花植株上饲养的重1.5倍、2.3倍和2.6倍（P≤0.05）。理化分析表明，干旱胁迫的叶片中对昆虫生长发育至关重要的游离氨基酸积累显著更多。与未胁迫叶片相比，胁迫叶片中的可溶性蛋白和可溶性碳水化合物也更丰富。尽管干旱胁迫植株的营养质量明显提高，但幼虫存活率却降低了，可能是因为限制因素变成了水。与未胁迫叶片相比，干旱胁迫叶片被消耗的棉花叶面积更大（P≤0.05），这可能是因为幼虫不得不将更多同化能量用于代谢，以通过呼吸产生的代谢水补充身体水分。本文讨论了寄主植物营养质量提高与产卵偏好之间的关联，以及相反地，与存活率降低之间的关联。
