Low-temperature tolerance of false codling moth Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) in South Africa

(1) The low-temperature tolerance of false codling moth (FCM) Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a significant aspect of this pest's population dynamics and has implications for post-harvest control and sterile insect technique programs.

(2) Here, we report results of experiments examining the effects of time, temperature and their interactions on low-temperature tolerance in adult FCM. In addition, using a variety of thermal pre-treatments, we examine the potential for hardening responses over several hours to improve low-temperature tolerance in FCM.

(3) Lower lethal temperature assays showed significant effects of time, temperature and significant interactions between time and temperature on survival (p<0.0001 in all cases). The temperature at which the probability of survival of 50% of the FCM population after 2 h of exposure was −4.5 °C, which varied significantly to −0.5 °C in 10 h. Gender and early adult age did not affect low-temperature tolerance of FCM.

(4) Using a range of non-lethal, low- and high-temperature pre-treatments, FCM survival could not be increased (p>0.84) and thus limited evidence for rapid cold hardening was found. These results are discussed with respect to microclimate temperatures in typical FCM environments and have implications for understanding population dynamics in this species and the diversity of low-temperature responses of insects.

Keywords: Hardening effects; Cold shock; Thermotolerance;Integrated pest management; Citrus; Acclimation