Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 5, 2002
Publication Date: February 1, 2003
Citation: YOCUM, G.D. ISOLATION AND CHARACTERIZATION OF THREE DIAPAUSE ASSOCIATED TRANSCRIPTS FROM THE COLORADO POTATO BEETLE, LEPTINOTARSA DECEMLINEATA. JOURNAL OF INSECT PHYSIOLOGY. 49(2):161-169. 2003. Interpretive Summary: The ability to overwinter in the temperate zone determines the possible geographic range of both natural and introduced species. The severity of economic loss caused by a pest insect is directly linked to the number of individuals that survived the previous winter to establish the new generation. Diapause (dormancy) is the central physiological mechanism enabling insects to survive winter conditions. Therefore, the mechanisms regulating diapause offer targets for developing novel means of pest control. Diapause is also being explored as a means of storing beneficial insects used in Integrated Pest Management (IPM) programs. I investigated the molecular mechanism involved in the initiation of diapause in the Colorado potato beetle, Leptinotarsa decemlineata, which is the major pest of potato in North America and Europe. Three diapause-regulated genes were isolated, two of which are new to science. These genes were expressed prior to the beetle entering diapause and expression persisted throughout diapause.
Technical Abstract: Using suppressive subtractive hybridization, fragments of three diapause-associated transcripts (DAT-1, 2 and 3) were isolated from the Colorado potato beetle, Leptinotarsa decemlineata. Full length clones were developed for the transcripts. DAT 1 encodes a deduced protein 286 amino acids in length with limited identity to several proteins with leucine-rich domains. DAT-2 encodes a deduced protein 229 amino acids in length with identity to the desiccation stress protein from Tenebrio molitor. DAT-3 encodes a deduced protein 97 amino acids in length with identity to no known protein. DAT-1 and 2 have similar expression patterns as determined by northern blot analysis. Trace levels of these two transcripts are first detected in three day old diapause programmed adults with a significant increase in expression on day 6. Expression of DAT-3 begins on day 12 in diapause programmed adults and expression levels increase until the beetles enter diapause. Expression of DAT-1, 2 and 3 continue at least 60 days into diapause. Minor levels of DAT 1 are observed in day 9 nondiapausing adults, but no expression of DAT-2 or 3 is observed in nondiapausing adults.