Insect diapause phasing re-assessed and justified.
The paper in Proceedings of the National Academy of Sciences USA helps to justify our previously suggested conceptual framework of insect diapause as a dynamic succession of endogenously and exogenously driven changes in physiology.
Figure: Statistical analysis of transcriptional profiling using custom DNA microarrays representing 1,042 genes in the drosophilid fly Chymomyza costata. Proposed phases of diapause separate clearly from direct development and form well- delimited clusters in two-dimensional PCA plot.
Insects often overcome unfavourable seasons in a hormonally regulated state of diapause during which their activity ceases, development is arrested, metabolic rate is suppressed and environmental-stress tolerance is bolstered. An improved knowledge of diapause is essential for different reasons: providing hints on regulated metabolic suppression and life-span extension, understanding insect life cycles, developing the management strategies for economically important insects; accurately predicting the insect populations' responses to climate change. In this study, we highlight the fact that diapausing insects pass through a stereotypic succession of eco-physiological phases. By assaying the gradual dynamics in the transcriptome as the larva of drosophilid fly, Chymomyza costata, traverse the diapause developmental program, we can readily distinguish distinct diapause developmental phases associated with induction, initiation, maintenance, cold-acclimation, and termination by cold or by photoperiodic signal. Each phase is characterized by a specific pattern of gene expression, supporting the physiological relevance of the concept of diapause phasing. Accordingly, the concept should serve future researchers as a general platform for the unification of timing scales and the interpretation of various ‘-omics’ data, obtained in diverse insect species encountering different ecological situations. We argue such standardized phasing of diapause development is critical for further molecular dissection of the mechanistic basis of insect diapause.
Košťál V., Štětina T., Poupardin R., Korbelová J., Bruce A. W. (2017) Conceptual framework of the ecophysiological phases of insect diapause development justified by transcriptomic profiling. Proceedings of the National Academy of Sciences USA 114: 8532-8537 .