Do laboratory acclimation experiments predict field responses? Cold tolerance and metabolomic divergence in...

While thermal acclimation refers to the acquisition of thermal tolerance following sublethal pre-exposure under laboratory conditions, acclimatization describes the same plastic process occurring in the field, in response to both thermal and non-thermal cues. This distinction has led to concerns that laboratory experiments may not fully portray the costs and benefits of field acclimatization, particularly regarding overwintering capacity. We studied adult and developmental lab acclimation in Drosophila suzukii, at both constant and fluctuating regimes, as well as field acclimatization at various times of the year. We assessed cold tolerance and metabolomic profiles using targeted and untargeted tools. All acclimatory treatments promoted cold tolerance. Developmental acclimation and acclimatization produced comparable cold tolerance, exceeding that of adult acclimation. In acclimatized flies, cold tolerance rose progressively from September to December. Metabolomic profiles revealed shared cryoprotective compound accumulation, but also treatment-specific differences across acclimation and acclimatization treatments. Although constant laboratory acclimation is often assumed to fail to capture the intricacies of environmental variability and the associated phenotypic changes, our findings show that even this simple approach can serve as a robust predictor of D. suzukii's thermal tolerance mediated by natural acclimatization, thereby validating a broad body of laboratory research conducted on Drosophila and other insects.