DNA fingerprinting improves data collection efficiency and yield in a host-specificity test of a weed biological control candidate

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 used 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 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.