Data from: Thermal resilience may shape population abundance of two sympatric congeneric Cotesia species (Hymenoptera: Braconidae)

Basal and plasticity of thermal tolerance determine abundance, biogeographical patterns and activity of insects over spatial and temporal scales. For coexisting stemborer parasitoids, offering synergistic impact to the efficacy of biological control, mismatches in thermal tolerance may influence their ultimate impact in biocontrol programs under climate variability. Using laboratory-reared congeneric parasitoid species Cotesia sesamiae and Cotesia flavipes Cameron (Hymenoptera: Braconidae), we examined basal thermal tolerance to understand potential impact of climate variability on their survival and limits to activity. We measured upper- and lower -lethal temperatures (ULTs and LLTs), critical thermal limits [CTLs] (CTmin and CTmax), supercooling points (SCPs), chill-coma recovery time (CCRT) and heat knock-down time (HKDT) of adults. Results showed LLTs ranging -5 to 5°C and -15 to -1°C whilst ULTs ranged 35 to 42°C and 37 to 44°C for C. sesamiae and C. flavipes respectively. Cotesia flavipes had significantly higher heat tolerance (measured as CTmax), as well as cold tolerance (measured as CTmin) relative to C. sesamiae (P˂0.0001). While SCPs did not vary significantly (P>0.05), C. flavipes recovered significantly faster following chill-coma and had higher HKDT compared to C. sesamiae. The results suggest marked differential basal thermal tolerance responses between the two congeners, with C. flavipes having an advantage at both temperature extremes. Thus, under predicted climate change, the two species may differ in phenologies and biogeography with consequences on their efficacy as biological control agents. These results may assist in predicting spatio-temporal activity patterns which can be used in integrated pest management programs under climate variability.

温度耐受性的基础水平与可塑性决定了昆虫在时空尺度上的种群丰度、生物地理分布模式与活动规律。对于对生物防治效能具有协同增效作用的共栖蛀茎害虫寄生蜂而言，温度耐受性的不匹配可能会在气候多变的背景下，影响它们在生物防治项目中的最终防控效果。本研究以实验室饲养的同属寄生蜂物种——蔗螟侧沟茧蜂（Cotesia sesamiae）与稻螟侧沟茧蜂（Cotesia flavipes Cameron，膜翅目：茧蜂科）为研究对象，测定其基础温度耐受性（basal thermal tolerance），以解析气候多变性对其存活情况与活动上限的潜在影响。我们测定了两种成虫的上下致死温度（upper-lethal temperatures, ULTs与lower-lethal temperatures, LLTs）、临界热极限（critical thermal limits, CTLs，包括低温临界温度CTmin与高温临界温度CTmax）、过冷却点（supercooling points, SCPs）、冷昏迷恢复时间（chill-coma recovery time, CCRT）以及热击倒时间（heat knock-down time, HKDT）。结果显示，蔗螟侧沟茧蜂与稻螟侧沟茧蜂的低温致死温度分别为-5℃至5℃与-15℃至-1℃，高温致死温度分别为35℃至42℃与37℃至44℃。相较于蔗螟侧沟茧蜂，稻螟侧沟茧蜂的高温耐受性（以CTmax衡量）与低温耐受性（以CTmin衡量）均显著更高（P<0.0001）。尽管过冷却点无显著组间差异（P>0.05），但稻螟侧沟茧蜂在冷昏迷后的恢复速度显著更快，且热击倒时间也长于蔗螟侧沟茧蜂。研究结果表明，两种同属寄生蜂的基础温度耐受性响应存在显著差异，稻螟侧沟茧蜂在极端温度环境下均具有生存优势。因此，在预测的气候变化背景下，二者的物候与生物地理分布可能出现分化，进而影响其作为生物防治天敌的防控效能。本研究结果可为预测气候多变背景下的天敌昆虫时空活动模式提供参考，助力综合害虫管理方案的优化与应用。