Climatic seasonality provokes considerable variability in the physical conditions of streams. Although few studies have assessed systematically the temporal effects of climate on aquatic communities, the diversity and structure of odonate larval assemblages (suborders Anisoptera and Zygoptera) are predicted to be influenced by seasonality. To evaluate this hypothesis, we tested the predictions that (1) the genera and abundance richness of zygopteran and anisopteran larvae will decrease during periods of high precipitation, (2) the genera richness and abundance of the two suborders will be associated inversely with temperature, and (3) the composition of the zygopteran assemblage will be more affected by seasonality, in particular precipitation, than that of the Anisoptera, whose composition will be influenced primarily by temperature. We collected odonate larvae every three months over a 6-year period at a stream located in the Cerrado–Amazon forest transition zone and compared these data with data on the local climate from the same period. Our results indicate that the seasonal variation in precipitation had a significant effect on the abundance of both odonate suborders, but that, while the anisopteran genera richness was affected by precipitation, the zygopteran richness was not. We showed that temperature affected the abundance of both suborders, but had no effect on genera richness. As we predicted, the composition of the zygopteran larval assemblage was affected more by the climatic variables than the Anisoptera. In addition, while the Zygoptera were affected primarily by precipitation, the Anisoptera were influenced most by temperature. The results indicate that the timing of the emergence of odonate larvae is synchronized with the months preceding the rainy season, when a high density of larvae are recorded, which may reflect a strategy for both the avoidance of the effects of fluctuations in water levels and the exploitation of the relatively abundant food sources found in the terrestrial environment. Temperature also appears to contribute to this synchrony, by either accelerating or delaying the process of larval emergence.

气候季节性引起溪流物理条件的相当大的变化。尽管很少有研究系统地评估气候对水生群落的时间影响，但预计齿状幼虫组合（异翅目亚目和接合翅目亚目）的多样性和结构会受到季节性的影响。为了评估这一假设，我们测试了以下预测：（1）在高降水时期，合翅目和异翅目幼虫的属和丰度丰富度会降低，（2）这两个亚目的属丰度和丰度将与温度成反比， (3) 合翅目组合的组成受季节性特别是降水的影响大于异翅目，后者的组成主要受温度的影响。在 6 年的时间里，我们每三个月在位于塞拉多 - 亚马逊森林过渡区的一条溪流中收集一次齿状幼虫，并将这些数据与同期当地气候数据进行比较。我们的结果表明，降水的季节性变化对两个齿翅亚目的丰度都有显着影响，但是，虽然异翅目属丰富度受降水影响，但合翅目丰富度不受降水影响。我们表明温度影响两个亚目的丰度，但对属的丰富度没有影响。正如我们预测的那样，与异翅目相比，合翅目幼虫组合的组成受气候变量的影响更大。此外，虽然接合翅目主要受降水影响，但异翅目受温度影响最大。结果表明，齿形幼虫出现的时间与雨季前几个月同步，当时记录到高密度的幼虫，这可能反映了避免水位波动影响的策略和开发陆地环境中相对丰富的食物来源。温度似乎也有助于这种同步，通过加速或延迟幼虫出现的过程。