Estimating the differences in critical thermal maximum and metabolic rate of Helicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) across life stages

Temperature is a crucial driver of insect activity and physiological processes throughout their life-history, and heat stress may impact life stages (larvae, pupae and adult) in different ways. Using thermolimit respirometry, we assessed the critical thermal maxima (CT max -temperature at which an organism loses neuromuscular control), CO 2 emission rate (V́CO 2 ) and Q10 (a measure of V́CO 2 temperature sensitivity) of three different life stages of Helicoverpa punctigera (Wallengren) by increasing their temperature exposure from 25 °C to 55 °C at a rate of 0.25 °C min −1 . We found that the CT max of larvae (49.1 °C ± 0.3 °C) was higher than pupae (47.4 °C ± 0.2 °C) and adults (46.9 °C ± 0.2 °C). The mean mass-specific CO 2 emission rate (ml V́CO 2 h −1 ) of larvae (0.26 ± 0.03 ml V́CO 2 h −1 ) was also higher than adults (0.24 ± 0.04 ml V́CO 2 h −1 ) and pupae (0.06 ± 0.02 ml V́CO 2 h −1 ). The Q 10 : 25–35 °C for adults (2.01 ± 0.22) was significantly higher compared to larvae (1.40 ± 0.06) and Q 10 : 35–45 °C for adults (3.42 ± 0.24) was significantly higher compared to larvae (1.95 ± 0.08) and pupae (1.42 ± 0.98) respectively. We have established the upper thermal tolerance of H. punctigera , which will lead to a better understanding of the thermal physiology of this species both in its native range, and as a pest species in agricultural systems.