Molecular mechanisms and comparative transcriptomics of diapause in two corn rootworm species (Diabrotica spp.)

Authors: LECHETA, MELISE - University Of Kentucky; Nielson, Chad; FRENCH, BRYAN - Retired ARS Employee; NADEAU, EMILY - University Of Kentucky; TEETS, NICHOLAS - University Of Kentucky

Submitted to: Current Research in Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2024
Publication Date: 1/2/2025
Citation: Lecheta, M.C., Nielson, C.N., French, B.W., Nadeau, E., Teets, N.M. 2025. Molecular mechanisms and comparative transcriptomics of diapause in two corn rootworm species (Diabrotica spp.). Current Research in Insect Science. https://doi.org/10.1016/j.cris.2024.100104.
DOI: https://doi.org/10.1016/j.cris.2024.100104

Interpretive Summary: Rootworms (Diabrotica species) are an insect pest of corn that have an economic impact of more than $1B annually in the United States. The life cycle of rootworms, including their embryonic diapause (the temporary suspension of development of the embryo), tightly synchronizes rootworms with their host plants and causes them to be an annual pest on corn crops. The underlying regulatory mechanisms of diapause in this species have not been identified. We used RNA sequencing to investigate the mechanisms underpinning diapause in western corn rootworm and northern corn rootworm. Comparative analyses showed shared and distinct mechanisms between the two species. Our comprehensive assessment of diapause gene expression may provide tools for disrupting diapause, which may facilitate research and aid pest control. This study also sheds light on embryonic diapause mechanisms with broader implications for understanding diapause in other species.

Technical Abstract: The Diabrotica spp. complex includes economically significant agricultural pests, notably the western corn rootworm (WCR) and northern corn rootworm (NCR), which cause major losses in maize production. Rootworms undergo an obligate embryonic diapause to synchronize their life cycles with host plants, but the underlying regulatory mechanisms of diapause in this species have not been identified. Here we use RNA sequencing (RNA-seq) to investigate molecular mechanisms underpinning diapause in both WCR and NCR. Eggs from diapausing strains of both species were sampled at five distinct time points (immediately after oviposition, early diapause, mid-diapause, late diapause and post-diapause), and gene expression was compared to strains that have been selected for non-diapause development. Our results indicate that transcriptional regulation is dynamic during diapause, and a number of differentially regulated pathways and processes were specific to the diapausing strains. Specific processes involved in diapause include upregulation of stress response pathways and a general shutdown of the cell cycle, as well as differential regulation of insulin and ecdysone signaling. Comparative transcriptomic analyses indicated that while many gene expression changes were conserved across species, overall gene expression profiles were distinct, indicating that some transcriptional changes are species-specific, despite the close phylogenetic relationship and phenotypic similarity between these species. Our comprehensive assessment of diapause gene expression may provide tools for disrupting diapause, which may facilitate research and aid pest control. Additionally, this study establishes a comprehensive transcriptomic database for NCR, contributing to the genetic resources available for rootworms. Beyond its immediate relevance to rootworm biology, this study also sheds light on embryonic diapause mechanisms with broader implications for understanding this phenomenon across species.