Data from: The interactive effects of photoperiod and future climate change may have negative consequences for a wide-spread invasive insect

Increasing global temperatures may affect many ectotherms, including insects, although increasing temperatures are thought to benefit future populations through effects on adult size, fecundity, or populations. However, the way that temperature may interact with photoperiod is not well understood. We study this problem using the Asian tiger mosquito, Aedes albopictus, an important worldwide invasive whose future spread is thought to be affected by changes in climate. We investigated how mass at maturity varied with temperature (21, 25 ºC) across short and long photoperiods, using laboratory populations from the extreme ends of this species’ current U.S. range (Florida, New Jersey). These values were used to parametrize a model to predict optimal mass based on development times; the results of a second laboratory experiment under the same treatments were compared to model predictions. Warmer conditions shortened development times in females from all locations leading to either higher or lower mass depending on the photoperiod. We then used published mass-fecundity relationships to determine the consequences of mass on fecundity under our conditions. Under the majority of scenarios warming decreased predicted fecundity under long photoperiods, but proved beneficial under short photoperiods because the costs of fast development were offset by increased survival in the face of late-season freezing risk. However, fecundity was always low under short photoperiods, so the marginal benefit of warming appears negligible given its cost under long photoperiods when the majority of reproduction occurs. Thus, with northern range expansion, where colder weather currently limits this species, detrimental effects of warming on fecundity are likely, similar to those identified for mass. Unlike previous work that has shown benefits of a warming planet to insects like Aedes albopictus, our work predicts lower performance under warming conditions in summer across the current range, a prediction with implications for range expansion, disease dynamics, and populations.

全球气温升高可能会影响包括昆虫在内的诸多变温动物（ectotherm），尽管此前学界认为气温升高可通过影响成虫体型、繁殖力或种群规模，使未来种群获益。然而，温度与光周期（photoperiod）的交互作用机制仍未得到充分阐明。本研究以全球范围内极具入侵性的重要物种——白纹伊蚊（Aedes albopictus）为研究对象，其未来分布扩张被认为受气候变化的显著影响。我们选取该物种当前美国分布范围两端的实验室种群（佛罗里达种群与新泽西种群），探究了短、长两种光周期条件下，成熟个体体重随温度（21℃、25℃）的变化规律。上述实验数据被用于参数化模型，以基于发育时长预测最优体重；同时将相同处理条件下的第二项实验室实验结果与模型预测结果进行对比。升温均缩短了所有采样种群雌性个体的发育时长，但成虫体重的增减则取决于光周期条件。随后，我们结合已发表的体重-繁殖力关联数据，分析了本研究条件下体重对繁殖力的影响。在多数情景下，升温会降低长光周期条件下的预测繁殖力，但在短光周期条件下却能带来益处——这是因为快速发育的成本可被季末低温冻害风险下存活率的提升所抵消。不过，短光周期条件下的繁殖力始终处于较低水平，而多数繁殖活动均发生于长光周期时段，因此综合来看，升温所带来的边际收益可忽略不计，且会伴随相应成本。因此，在当前受低温限制的北部分布扩张区域，升温对繁殖力的负面影响或将显现，这与针对成虫体型得出的结论一致。与此前相关研究认为全球变暖对白纹伊蚊等昆虫存在益处不同，本研究预测，在当前分布范围内的夏季升温条件下，该物种的适合度将有所降低；这一预测对其分布范围扩张、疾病动态及种群发展均具有重要启示意义。