Lovett Gary M, Hart Julie E, Christenson Lynn M, Jones Clive G
Institute of Ecosystem Studies, Millbrook, NY 12545, USA e-mail:
Oecologia. 1998 Dec;117(4):513-516. doi: 10.1007/s004420050687.
The gypsy moth (Lymantria dispar L.), a major defoliator of hardwood forests in the eastern U.S., has a highly alkaline midgut pH. We hypothesized that the high pH would cause high rates of ammonia (NH) volatilization as larvae consumed foliage, leading to potentially large losses of N from the ecosystem to the atmosphere during gypsy moth outbreaks. We measured NH emission during the consumption of oak foliage by larvae in the laboratory. Surprisingly, we found very low amounts of NH release of about 0.1% of the N consumed in foliage. We speculate that digestive mechanisms may limit NH production in the midgut, and that the acidic environment of the hindgut traps most of the small amount of NH that is produced, effectively preventing a potentially very large N loss from both larvae and ecosystem. The estimated rate of NH emission from a defoliated forest is small compared to other inputs and outputs of N from the ecosystem, but could potentially enhance the neutralization of atmospheric acidity during the defoliation period.
舞毒蛾（Lymantria dispar L.）是美国东部阔叶林的主要食叶害虫，其肠道pH值呈强碱性。我们推测，随着幼虫取食树叶，高pH值会导致氨（NH）的挥发率升高，从而在舞毒蛾爆发期间，使生态系统中的氮大量流失到大气中。我们在实验室中测量了幼虫取食橡树树叶期间的氨排放量。令人惊讶的是，我们发现氨的释放量非常低，约为所食树叶中氮含量的0.1%。我们推测，消化机制可能会限制中肠中氨的产生，而后肠的酸性环境会捕获产生的少量氨，从而有效防止幼虫和生态系统中潜在的大量氮流失。与生态系统中氮的其他输入和输出相比，落叶林中氨的估计排放率较小，但在落叶期可能会增强对大气酸度的中和作用。
