Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2007
Publication Date: October 1, 2007
Citation: Coudron, T.A., Brandt, S.L., Hunter, W.B. 2007. Molecular profiling of proteolytic and lectin transcripts in Homalodisca vitripennis (Hemiptera: Auchenorrhyncha: Cicadellidae) feeding on sunflower and cowpea. Archives of Insect Biochemistry and Physiology. 66(2):76-88. Interpretive Summary: The glassy-winged sharpshooter (GWSS) has recently become established in California and is a major threat to the viticulture industry because it transmits a bacterium that causes several economically important citrus diseases. A more thorough analysis of the GWSS nutritional physiology will help scientists understand the host range of the GWSS, transmission processes, and assist in rearing methods necessary for further research. A putative digestive function was demonstrated for seven protein-degrading enzymes that were found in GWSS when reared on either of two host plants used in this study. Those results support the concept that proteins play a role in GWSS feeding and overall nitrogen nutrition which is an emerging concept for this species and order of insect. That concept and knowledge of the ampleness of the protein-degrading enzymes will have a significant impact on which methods scientists will select to be tested for the control of the GWSS.
Technical Abstract: Homalodisca vitripennis Germar 1821 (Hemiptera: Cicadellidae) (Takiya et al. 2006, syn. H. coagulata (Say)) gut and salivary gland EST libraries were used to isolate cDNA fragments of the genes encoding for cathepsin L, asparaginyl endopeptidase, cathepsin B, metalloendopeptidase, cathepsin D, multicatalytic endopeptidase and a sugar-binding C-type lectin. Transcript levels were evaluated in immature and adult H. vitripennis feeding on sunflower (Helianthus annuus) or cowpea (Vigna unguiculata). Northern blot hybridization results showed that expression of most of the transcripts were similar for all developmental stages and feeding on the two diets examined. However, on host plants the expression of the transcript for asparaginyl endopeptidase was less expressed in sunflower-fed adult females compared to sunflower-fed immatures. Expression of the C-type lectin transcript was up-regulated in adults compared to immatures when fed on either diet. Documenting both the presence and variation of transcript expression involved in putative digestive proteolysis in this xylem feeding leafhopper is noteworthy and aids efforts to design specific diet formulations for mass production of hosts and parasitoids to be used as effective biological control measures.