False codling moth Thaumatotibia leucotreta (Lepidoptera,Tortricidae) larvae are chill-susceptible

Leigh Boardman; Tim G.Grout; John S.Terblanche

摘要

This study reports on the low temperature tolerance and cold hardiness of larvae of false codling moth,Thaumatotibia leucotreta.We found that larvae have mean critical thermal minima (lower limits of activity) of 6.7℃ which was influenced by feeding status.The effects of low temperature exposure and duration of exposure on larval survival were assessed and showed that the temperature at which 50％ of the population survives is -11.5 ± 0.3℃ after 2 h exposure.The supercooling point (SCP,i.e.,freezing temperature) was investigated using a range of cooling rates and under different conditions (feeding and hydration status) and using inoculative freezing treatments (in contact with water or orange juice).The SCP decreased significantly from - 15.6 ℃ to - 17.4℃ after larvae were fasted for 24 h.Twenty-four hour treatments at either high or low relative humidity (95.9％ or 2.4％) also significantly decreased SCP to -17.2℃ and -18.2℃ respectively.Inoculative freezing (by water contact) raised SCP from - 15.6℃ to -6.8℃which could have important implications for post-harvest sterilization.Cooling rates did not affect SCP which suggests that there is limited phenotypic plasticity of SCP during the larval life-stage,at least over the short time-scales investigated here.In conclusion,larvae of T.leucotreta are chill-susceptible and die upon freezing.These results are important in understanding this pest's response to temperature variation,understanding pest risk status and improving post-harvest sterilization efficacy.

机译：本研究报道了假co蛾（Thaumatotibia leucotreta）幼虫的低温耐受性和抗寒性。我们发现，幼虫的平均临界热最小值（活性下限）为6.7℃，受摄食状态的影响。评估暴露于温度和暴露持续时间对幼虫存活的影响，并显示暴露2 h后其存活率为50％的种群的温度为-11.5±0.3℃。使用以下方法研究过冷点（SCP，即冷冻温度）：禁食24小时后，SCP从-15.6℃降至-17.4℃，在不同条件下（进食和水合作用）和接种接种冷冻处理（与水或橙汁接触）的冷却范围。二十岁在相对湿度高或低（95.9％或2.4％）的情况下进行四个小时的治疗也将SCP分别显着降低至-17.2℃和-18.2℃。接种冷冻（通过接触水）提高了SC P从-15.6℃到-6.8℃可能对收获后的杀菌有重要意义。冷却速率没有影响SCP，这表明在幼虫的生命阶段，至少在短期内，SCP的表型可塑性有限-综上所述，T.leucotreta的幼虫易感冷并在冷冻时死亡。这些结果对于了解该害虫对温度变化的响应，了解害虫风险状况以及提高收获后的杀菌效果具有重要意义。

False codling moth Thaumatotibia leucotreta (Lepidoptera,Tortricidae) larvae are chill-susceptible

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