Physiological and transcriptional changes associated with obligate aestivation in the cabbage stem flea beetle (Psylliodes chrysocephala)

Abstract

Aestivation is a form of seasonal dormancy observed in various insect species, usually coinciding with the summer season. Psylliodes chrysocephala (Coleoptera: Chrysomelidae), the cabbage stem flea beetle, is a key pest of oilseed rape and obligatorily aestivates as adult in late summer. At present, our understanding of the physiological and transcriptional changes linked to aestivation in P. chrysocephala is still limited. In this study, physiological parameters and RNA-seq analyses were performed with laboratory-reared beetles at pre-aestivation, aestivation, and post-aestivation stages. Measurements of CO2 production supported the notion that aestivating beetles dramatically reduce their metabolic rate and, together with assessments of reproductive maturation, allowed precise discrimination between the three adult stages. Aestivating beetles showed a reduction in carbohydrate reserves and an increase in lipid reserves compared to pre-aestivating beetles, indicating that aestivation is associated with drastic changes in energy metabolism. In agreement with these findings, we found that genes involved in carbohydrate and lipid metabolism, digestion, and mitochondrial activity are differentially expressed between the three stages. Furthermore, RNA-seq analysis suggested the regulation of transcription factors associated with aestivation maintenance and the involvement of cytochrome P450s in conferring a summer-resistant phenotype during the aestivation period. In conclusion, this study represents the first exploration of the transcriptomic and physiological aspects of the aestivation response in P. chrysocephala.

Effective target genes for RNA interference-based management of the cabbage stem flea beetle

“…We used our de novo transcriptome assembly representing various adult stages of female CSFB with a BUSCO v5.4.2 (Manni et al, 2021) completeness score of 95.9% (S:94.5%, D: 1.4%, F: 1.8%, M: 2.3%, n: 2124, comparison against the endopterygota v4 dataset) (Güney et al ., 2024, NCBI BioProject: PRJNA930726, TSA: GKIH01000001:GKIH01098921 ) to identify candidate gene sequences. Orthofinder v2.5 (Emms & Kelly, 2019) with the default parameters was used to conduct orthology inference between the translated amino acid sequences from CSFB and Tribolium castaneum (Tcas5.2 from www.ibeetle-base.uni-goettingen.de).…”