Influence of rainfall regime in the Cerrado biome on the maintenance of traps built by Myrmeleon brasiliensis (Navás) (Neuroptera: Myrmeleontidae) larvae and the morphology of adults

ABSTRACT Seasonality in the Cerrado biome of Brazil is characterized by a dry season and a rainy season, affecting the availability of water and generating nutritional limitations. Thus, plants and animals have developed adaptive mechanisms in order to survive in this environment. Insects known as antlions (Neuroptera: Myrmeleontidae) occur in areas of the Cerrado and build traps in dry soil to capture prey items. In the rainy season, these insects are unable to forage due to the waterlogged soil. The aim of this study was to investigate the influence of the rainfall regime in the Cerrado on aspects of trap-building behavior, larval development and morphological characteristics of adult antlions. Larvae of the antlion Myrmeleon brasiliensis (Návas, 1914) were observed and collected in an area of the Cerrado biome in the municipality of Aquidauana (MS), Brazil. Observations were performed in the rainy and dry seasons to determine the abundance of traps built by M. brasiliensis larvae. In the laboratory, experiments were performed involving the manipulation of the frequency of simulated rain on the traps. The results revealed that variations in rainfall due to seasonality in the Cerrado affect M. brasiliensis larvae, with greater foraging observed in the dry season. The laboratory experiments demonstrated that differences in the frequency of rains affect the mortality of the larvae, larval development time and the size of the adults. Thus, variations in rainfall patterns can lead to variations in the characteristics of the population structure of M. brasiliensis in areas of the Cerrado biome in Brazil.

摘要 巴西塞拉多生物群区（Cerrado biome）的季节性变化以旱季与雨季为典型特征，其会影响区域内水资源可利用性并引发营养限制。为此，当地动植物演化出各类适应机制以在此环境中存活。蚁蛉（antlions，脉翅目蚁蛉科Neuroptera: Myrmeleontidae）广泛分布于塞拉多区域，它们会在干燥土壤中构筑陷阱以捕获猎物。雨季时，土壤积水会导致此类昆虫无法开展觅食活动。本研究旨在探究塞拉多的降雨节律对蚁蛉筑巢行为、幼虫发育及成虫形态特征的影响。研究人员在巴西南马托格罗索州（MS）阿基达乌阿纳市的一处塞拉多生物群区，对巴西蚁蛉（*Myrmeleon brasiliensis*，Návas, 1914）的幼虫进行了观察与采集。研究分别在雨季与旱季开展观测，以统计巴西蚁蛉幼虫构筑的陷阱丰度。实验室中，研究人员通过调控模拟降雨的频率开展相关陷阱实验。实验结果显示，塞拉多季节性降雨的变化会对巴西蚁蛉幼虫产生显著影响：旱季的觅食活动更为活跃。实验室实验进一步证实，降雨频率的差异会影响幼虫的死亡率、发育时长及成虫体型。综上，降雨模式的变化可导致巴西塞拉多生物群区内巴西蚁蛉种群结构特征出现差异。