Submitted to: Genbank
Publication Type: Other
Publication Acceptance Date: 7/16/2007
Publication Date: 7/17/2007
Citation: Chirumamilla, A., Yocum, G.D., Boetel, M.A., Buckner, J.S., Dregseth, R.J. 2007. Multi-year survival of sugarbeet root maggot larvae, Tetanops myopaeformis in cold storage. Genbank. Accession numbers: EV413916 to EV413927.
Technical Abstract: Sugarbeet Root Maggot (SBRM), Tetanops myopaeformis (Röder) (Diptera: Ulidiidae), is considered the most serious economic insect pest of sugarbeet in the Red River Valley of Minnesota and North Dakota as well as in the western United States and province of Alberta in Canada. Typically univoltine and freeze tolerant, it survives the winters by undergoing diapause as a matured 3rd-instar larva. SBRM, as 3rd-instar larvae, have a remarkable ability to survive more than five years when stored in the laboratory at 6±1 deg. C. Although presumably started as diapausing larvae, it was not certain whether they were maintaining the same physiological status over five years of long-term storage. They might be remaining in prolonged diapause as a result of either a simple extension of normal winter diapause or from re-entering a second diapause after resuming their development following the winter diapause. Alternatively, the larvae may be in a state of post-diapause quiescence waiting for favorable temperatures. In this study, we test the hypothesis that long-term survival was facilitated by larvae maintaining a state of diapause. Understanding the physiological status and mechanisms enabling prolonged survival of SBRM larvae in storage will allow us to gain better insights into the phenology and field physiology of SBRM. This work could also shed light on the endogenous mechanisms of diapausing insects. Moreover, this strategy can serve as an important cost-effective technique to improve the cold storage of mass-reared insects. In this study, we investigated differential gene expression pattern of the laboratory stored larvae to that of known diapausing SBRM larvae collected from the field during the current winter season. Transcript of Fat Body Protein 2 (FBP2) was found expressed in diapausing larvae but was at or below detection level in 1-, 2-, and 5-year old larvae. FBP2 has been shown to have alcohol dehydrogenase activity. Our results have shown that all the groups of stored larvae had mixed populations of prolonged diapause and post-diapause quiescent larvae. The key for extended survival of SBRM was definitely not diapause because the majority of larvae were in a quiescent state. The fact that a fraction of the population were in prolonged diapause reveals that SBRM has the inherent ability to undergo prolonged diapause, and the frequency or dynamics of its occurrence in field situations should be investigated.