Diurnal temperature amplitude is known to have a large influence on insect life history. Population density affects intraspecific competition and many other aspects of insect life history. However, there is limited information on the interactive effects of these factors on insects. Here, we tested the interactive effects of three diurnal temperature amplitudes (22 ± 0°C, 22 ± 6°C, and 22 ± 12°C) and three population densities on the development, survival, longevity, and fecundity of the English grain aphid Sitobion avenae (Fabricius) (Homoptera: Aphididae). At a constant temperature, increasing population density reduced the growth and survival of early-instar nymphs, increased longevity, and reduced fecundity. At a low population density, increasing temperature amplitude inhibited nymph development. However, even at a high temperature amplitude, nymph survival rate was higher than expected, and reproduction was possible because the recovery of the lower night-temperatures eliminated thermal stress. Increasing the population density reduced, and even reversed, the negative effects of the wide temperature amplitude. This may reflect synergistic interactions between population density and wide temperature amplitude as these stressors each incur energetic costs. These findings emphasize the importance of temperature amplitude and population density for improving prediction accuracy and damage assessment during pest control modeling.

中文翻译：

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宽昼夜温幅和高种群密度可积极影响 Sitobion avenae（半翅目：蚜科）的生活史

众所周知，昼夜温度幅度对昆虫的生活史有很大影响。种群密度影响种内竞争和昆虫生活史的许多其他方面。然而，关于这些因素对昆虫的相互作用影响的信息有限。在这里，我们测试了三个昼夜温度幅度（22 ± 0°C、22 ± 6°C 和 22 ± 12°C）和三个种群密度对英国谷物的发育、生存、寿命和繁殖力的交互影响蚜虫 Sitobion avenae (Fabricius) (同翅目：蚜科)。在恒定温度下，增加种群密度会降低早龄若虫的生长和存活率，延长寿命并降低繁殖力。在低种群密度下，温度幅度的增加会抑制若虫的发育。然而，即使在高温度幅度下，若虫存活率高于预期，并且由于夜间较低温度的恢复消除了热应激，因此繁殖是可能的。增加人口密度减少甚至逆转了宽温度幅度的负面影响。这可能反映了人口密度和宽温度幅度之间的协同相互作用，因为这些压力源都会产生能量成本。这些发现强调了温度幅度和种群密度对于提高害虫控制建模期间的预测准确性和损害评估的重要性。宽温度幅度的负面影响。这可能反映了人口密度和宽温度幅度之间的协同相互作用，因为这些压力源都会产生能量成本。这些发现强调了温度幅度和种群密度对于提高害虫控制建模期间的预测准确性和损害评估的重要性。宽温度幅度的负面影响。这可能反映了人口密度和宽温度幅度之间的协同相互作用，因为这些压力源都会产生能量成本。这些发现强调了温度幅度和种群密度对于提高害虫控制建模期间的预测准确性和损害评估的重要性。