极端高温和持续中等高温对小菜蛾耐热性的影响

Stage-specific Heat Tolerance of Plutella xylostella under Extreme and Moderate High Temperatures

气候变化频率的增加和持续时间的延长,导致具有较短生活史的大部分农业害虫的某一个或某几个生命阶段都可经历热浪的胁迫。热浪对小型昆虫的生态学效应取决于不同生命阶段的耐热性,因而解析特定龄期下昆虫生命阶段的耐热性对理解气候变暖热浪频发的生态学影响具有重要意义。本研究以世界重要蔬菜害虫小菜蛾为研究对象,试验了小菜蛾4龄幼虫、成虫的基底耐热性和诱导耐热性,以及1龄幼虫和3龄幼虫置于不同高温[(31±1)、33±1)、35±1)℃]和暴露时间(3、6、9、12d)组合的持续中等高温耐热性。试验发现幼虫和成虫具有不同的基底和诱导耐热性,具有较弱基底耐热性的幼虫反而具有更强的诱导耐热性。不同生命阶段在持续数天的中等高温胁迫下具有不同的存活表现,早期生命阶段存活率较后期阶段的低,而且这种差异在较强高温下表现得尤为明显。昆虫不同阶段耐热性的差异,对种群的维持具有重要的生态学意义。大多数农业害虫田间种群具有混合年龄结构,热浪后耐热的发育阶段的存活,保证种群可以一直生存和繁衍下去。

One or more life stages of most agricultural pests with short life cycles can be subjected to heat wave stress because of substantially increased frequency and duration of climate change. The ecological effects of heat waves on small insects depend on the thermal tolerance of different life stages. Therefore, analyzing thermal tolerances of insects in their life stages at specific ages is of great significance for understanding the ecological impact of frequent heat waves and climate warming. A worldwide important pest on cruciferous vegetables, diamondback moth Plutella xylostella was used as the test material, the basal thermal tolerance and induced thermal tolerance of 4th larvae and adult were measured, continuous moderate high temperature thermal tolerance of the 1st and 3rd larvae combined with different high temperatures [(31±1),(33±1),(35±1)℃] with exposure time (3,6,9,12 d) were also measured in this study. The results indicated that larvae and adult showed different basal and induced thermal tolerances, larvae with weak basal thermal tolerance showed stronger induced thermal tolerance. Larvae in different life stages showed different survival rates under continuous several days of moderate high temperature stress, larvae have lower survival rate in early life stages than in later life stages. Moreover, this difference is particularly obvious at higher temperatures. The differences of thermal tolerances in different stages of insects have important ecological significance for the maintenance of population. The most agricultural pests have a mixed age structure in their field populations, survival of thermal resistant developmental stage of pests after heat wave will ensure the populations can still survive and reproduce.