Abstract：
Due to climate change, many regions are experiencing progressively milder winters. Consequently, pest insects from warm regions, particularly those with some tolerance to low temperatures, could expand their geographic range into these traditionally colder regions. The palm borer moth (Paysandisia archon) is a Neotropical insect that in recent decades has reached Europe and Asia as one of the worst pests of palm trees. Little is known about its ability to tolerate moderately cold winters and, therefore, to colonize new areas. In this work, we characterized the cold tolerance of Paysandisia archon by measuring its thermal limits: median lethal-temperature, LT50, chill-coma onset temperature, CTmin, supercooling point, SCP, freezing time and freezing survival. We found that this species was able to survive short periods of complete freezing, with survival rates of 87% after a 30-min freezing exposure, and 33% for a 1 h-exposure. It is then a moderately freeze-tolerant species, in contrast to all other lepidopterans native to warm areas, which are freeze-intolerant. Additionally, we investigated whether this insect improved its cold tolerance after either short or long pre-exposure to sub-lethal low temperatures. To that end, we studied potential changes in the main thermo-tolerance parameters and, using X-ray Computed Tomography, also in the morphological components of pretreated animals. We found that short pre-exposures did not imply significant changes in the SCP and CTmin values. In contrast, larvae with long pretreatments improved their survival to both freezing and low temperatures, and required longer times for complete freezing than the other groups. These long-term pre-exposed larvae also presented several morphological changes, including a reduction in water content that probably explained, at least in part, their longer freezing time and higher freezing survival. Our results represent the first cold tolerance characterization of this pest insect, which could be relevant to better design strategies to combat it.
摘要：
由于气候变化,许多地区正在经历越来越温和的冬天。因此,来自温暖地区的害虫，特别是那些对低温有一定耐受性的，可以将其地理范围扩展到这些传统上较冷的地区。棕榈树蛾（Paysandisiaarchon）是一种新热带昆虫，近几十年来，它已成为欧洲和亚洲最严重的棕榈树害虫之一。人们对它能够忍受中度寒冷的冬天的能力知之甚少，因此,殖民新的地区。在这项工作中,我们通过测量其热极限来表征Paysandisiaarchon的耐寒性：中位致死温度，LT50，寒战昏迷发作温度，CTmin,过冷点,SCP,冷冻时间和冷冻存活率。我们发现这个物种能够在短时间内完全冻结，冷冻暴露30分钟后的存活率为87%，和33%的1小时暴露。它是一种中等耐冻的物种，与所有其他产于温暖地区的鳞翅目相反，不耐冻结。此外,我们调查了这种昆虫在短期或长期暴露于亚致死低温后是否提高了其耐寒性。为此,我们研究了主要耐热性参数的潜在变化，用X射线计算机断层扫描,也在预处理动物的形态成分中。我们发现，短暂的暴露前并不意味着SCP和CTmin值的显着变化。相比之下,长期预处理的幼虫提高了它们在冷冻和低温下的存活率，并且需要比其他组更长的时间才能完全冻结。这些长期暴露前的幼虫也出现了一些形态变化，包括可能解释的水含量的减少，至少在某种程度上,它们更长的冷冻时间和更高的冷冻存活率。我们的结果代表了这种害虫的第一个耐寒性特征，这可能与更好的设计策略来对抗它有关。
