Biological and physiological responses of Bradysia odoriphaga 4th instar larvae to long-term constant and fluctuating mild heat stress
Zhu, Guodong; Xue, Ming (2022), Biological and physiological responses of Bradysia odoriphaga 4th instar larvae to long-term constant and fluctuating mild heat stress, Dryad, Dataset, https://doi.org/10.5061/dryad.37pvmcvmr
Global climate change can expose insects to high-temperature stress, including extreme and mild heat stress. For soil insects, mild heat stress is more common than extreme heat stress. High summer temperature is a key barrier for Bradysia odoriphaga (Diptera: Sciaridae), a devastating soil pest of vegetables in China. The 4th instar larvae possess the strongest thermal tolerance to high temperatures. To determine whether the 4th instar larvae of B. odoriphaga possess other adaptations to summer mild heat stress besides thermal plasticity, we evaluated the biological performance of 4th instar larvae under constant and fluctuating long-term mild heat stress. The physiological responses were studied including energy storage, hormone level, and expression of related genes. Bioassay results indicated that 4th instar larvae survived, without pupation, for more than 40 days under long-term mild heat stress (34°C). Combined with constant and fluctuating treatment, mild heat stress delayed larval development, reduced longevity, and reduced fecundity. However, a summer diapause-like phenomenon was observed, including larval development stasis under mild heat stress and a prolonged recovery time after mild heat stress. Protective physiological responses were involved in regulating the larval stage including accumulating fat and glycogen, a high level of juvenile hormone, and a low level of molting hormone. Also, high expression levels of hsp70 and hsp90 were detected. The delayed development of B. odoriphaga 4th instar larvae appears to be a special adaptation strategy to withstand mild heat stress in summer, and it is regulated by complex physiological processes.
Shandong Provincial Natural Science Foundation, Award: ZR201911130528