NATURAL ENEMIES MAY BE A CAUSE OF DISCRETE GENERATIONS IN TROPICAL INSECTS
NATURAL ENEMIES MAY BE A CAUSE OF DISCRETE GENERATIONS IN TROPICAL INSECTS
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DOI：
10.1038/327144a0
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发表时间：
1987-05-14
期刊：
影响因子：
64.8
通讯作者：
HASSELL, MP
中科院分区：
文献类型：
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作者：
GODFRAY, HCJ;HASSELL, MP
人们普遍认为，温带地区明显的季节性导致生活在那里的昆虫往往有离散的世代，而在热带地区，由于或多或少连续的有利条件，世代更有可能重叠。然而，这些笼统的概括具有误导性。现在已知热带昆虫种群的几个例子，它们在平衡1 -5（图1a）和非平衡条件6 -9下往往表现出离散的世代，这不是季节性决定的。我们还对在恒定条件下培养的实验室昆虫种群显示离散世代的频率感到震惊10 -12（图1b）。这些例子中的一个共同因素是昆虫寄生物作为主要死亡因素的存在。在这里，我们证明，使用理论人口模型，寄生的一种方式，可以近似离散世代的原因。特别是，我们表明，主机和寄生蜂的生命周期的长度的比例是最重要的，在确定世代是否往往是离散或连续的，并讨论了这在生物控制的重要性。
It is commonly believed that the marked seasonally of temperate regions results in the insects that live there often having discrete generations, whereas in the tropics, generations are more likely to overlap because of the more-or-less continuously favourable conditions. These sweeping generalizations, however, are misleading. Several examples are now known of tropical insect populations that tend to show discrete generations, both under equilibrium1–5(Fig. la) and non-equilibrium conditions6–9, which are not seasonally determined. We are also struck by the frequency with which laboratory insect populations cultured under constant conditions show discrete generations10–12(Fig. 1b). A common factor in these examples is the presence of insect parasitoids as a major mortality factor. Here we demonstrate, using theoretical population models, one way in which parasitism can be the cause of approximately discrete generations. In particular, we show that the ratio of the lengths of the host and parasitoid life cycles is of prime importance in determining whether generations tend to be discrete or continuous and discuss the importance of this in biological control.