|De Biase, Alessio|
Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2010
Publication Date: 10/1/2010
Citation: Rector, B.G., De Biase, A., Cristofaro, M., Primerano, S., Belvedere, S., Antonini, G., Sobhian, R. 2010. DNA fingerprinting to improve data collection efficiency and yield in an open-field host-specificity test of a weed biological control candidate. Journal of Invasive Plant Science and Management. 3:429-439. Interpretive Summary: Yellow starthistle (YST) is a serious problem weed of rangelands and other public and private lands in the western U.S. An ongoing ARS biological control program for this weed has produced several biological control agents to attack this weed, including the root-boring weevil, Ceratapion basicorne. In this study, an open-field test was conducted in southern France to investigate the host-specificity of a local population of C. basicorne. DNA fingerprinting techniques were used in order to be able to identify larval and other immature insect specimens to the species level, based on comparison of certain key DNA sequences. This technique was necessary because several other Ceratapion spp. were known to occur in the area, so it was imperative to be able to effectively distinguish between the closely related species present. The DNA fingerprinting technique allowed for a higher data yield (i.e. higher percentage of collected specimens identified) and required fewer taxonomist-hours than conventional means. The French population of C. basicorne displayed a sufficiently limited host-range in this test to be worthy of further study in the event that a population from this region is desired for release against YST in the U.S.
Technical Abstract: An open-field test was conducted in southern France to assess the host-specificity of Ceratapion basicorne, a candidate for biological control of yellow starthistle (Centaurea solstitialis; YST). Test plants were infested by naturally occurring populations of C. basicorne but were also exposed to sympatric herbivore species, including other Ceratapion spp. Insects from the test plants were collected directly into tubes of ethanol and subsequently identified to species according to DNA sequence similarity with morphologically identified reference specimens. This morpho-molecular identification method was attempted in an effort to maximize the amount of data gained in the field bioassay. Data in such experiments is frequently lost in attempting to rear immature insects from test plants into adults suitable for conventional morphological identification. Another goal of using the morpho-molecular identification method is to minimize the number of taxonomist-hours necessary to complete such a study. The results obtained here showed that the French C. basicorne population only attacked YST and Centaurea cyanus, another known host of C. basicorne. Molecular phylogenetic analysis of the insects collected from all other non-host plants rejected the possibility that any were C. basicorne. The morpho-molecular species identification technique facilitates analysis of open-field host-specificity bioassays in large part by reducing the number of taxonomist-hours required.