The molecular response of Neoseiulus bicaudus to cold acclimation.

Neoseiulus bicaudus is a beneficial predatory mite used for the control of spider mites. Temperature is a crucial factor that influences the distribution, growth, and development of N. bicaudus. Cold acclimation is an important arthropod strategy used to improve cold tolerance. We investigated the impact of cold acclimation on the cold tolerance of N. bicaudus. To gain insights into the molecular mechanisms underlying cold acclimation of N. bicaudus, we conducted transcriptome and proteomic analyses on three cold-acclimated groups (6-h: 3 °C for 6 h; 24-h: 3 °C for 24 h; 7-day: 9 °C for 7 d). Cold acclimation, especially in the 7-day treatment, significantly improved the survival time of N. bicaudus at an acute low temperature (-6 °C). Multi-omics analysis revealed that cold acclimation in N. bicaudus involves coordinated regulation of genes and proteins related to energy metabolism and cellular protection. Cold acclimation suppressed energy-intensive pathways like fatty acid synthesis and glycolysis, reducing energy expenditure. However, it enhanced expression of proteins in fatty acid oxidation, tricarboxylic acid cycle, and oxidative phosphorylation pathways to maintain energy balance. Moreover, cold acclimation upregulated genes and proteins involved in mRNA processing, transport, translation regulation, protein folding, and degradation, ensuring rapid repair and synthesis of proteins for homeostasis. RNA interference of NbHSP70 and NbHSP90 showed that these genes play a vital role in regulating the cold tolerance of N. bicaudus. These findings provide valuable resources and opportunities to uncover molecular acclimation mechanisms that support cold tolerance in Phytoseiid mites.