Submitted to: European Journal of Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2009
Publication Date: 10/20/2009
Citation: Yocum, G.D., Rinehart, J.P., Larson, M.L. 2009. Down Regulation of Gene Expression Between the Diapause Initiation and Maintenance Phases of the Colorado Potato Beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). European Journal of Entomology. 106(4):471-476.
Interpretive Summary: The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is the major defoliator of potato and also feeds on tomato and eggplant. The CPB is endemic in most of the potato growing regions worldwide. Dormancy in the form of diapause or quiescence enables insects to survive and synchronize their life cycles to the abiotic and biotic factors needed for development and reproduction. Dormancy in the CPB can take the forms of diapausing for a single winter, prolonged diapause lasting for more than one winter, repeated diapause, i.e., single winter diapauses interrupted by reproduction cycles and summer diapause (quiescence). In addition to the various forms of diapause, there is a considerable degree of intra- and inter-population variation in the phenotypic expression of diapause. The plasticity of the CPB diapause response has played a key role in its range expansion. In order to monitor and model CPB phenology under field conditions and develop an understanding of the mechanism(s) involved in this variation, reliable biomarkers are needed. Here we study the transition between the diapause initiation phase (IP) and the diapause maintenance phase (MP). To further clarify the molecular regulation of this dynamic period of transition in the life cycle of L. decemlineata, research was conducted with two main objectives: (1) isolate additional IP and MP differentially regulated genes and (2) examine the expression of these genes during the early gonotrophic cycle in nondiapausing adults.
Technical Abstract: The diapause initiation and maintenance phases of the Colorado potato beetle, Leptinotarsa decemlineata were screened. Eight transcripts were found to be down regulated as the beetles enter the diapause maintenance phase of diapause development after day 15 postemergence. These transcripts were also expressed in early nondiapausing adults. In nondiapausing beetles, two distinct expression patterns were noted. In the first group, the expression of the transcripts persisted until day 9 postemergence and was still expressed in most day 11 individuals examined. In the second group, the highest level of expression was seen only until day 5 or 7, and was at trace levels or below the level of detection on days 9 and 11. Using BlastX, the transcripts were placed into six broad categories: unknown function, regulatory, structural, protease, retinol binding and carbohydrate metabolism.