|Smith, Lincoln - Link|
Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/24/2009
Publication Date: 8/24/2009
Citation: Antonini, G., Coletti, G., Serrani, L., Tronci, C., Cristofaro, M., Smith, L. 2009. Using molecular genetics to identify immature specimens of the weevil Ceratapion basicorne (Coleoptera, Apionidae). Biological Control. 51:152-157. Interpretive Summary: Discovery of new insect agents for biological control of weeds requires taxonomic identification. Larvae are more closely associated with their host plant than adults, but it is generally not possible to identify larvae to species using conventional morphological methods. Molecular genetic tools can be used to identify larvae, and thus help determine host plant specificity of prospective biological control agents. Here we present an example of the use of molecular genetics to distinguish larvae of Ceratapion basicorne, a prospective biological control agent for yellow starthistle, from closely related species. The method successfully distinguished among 5 closely related species of weevils, and confirmed that C. basicorne does not attack safflower under field conditions. Use of molecular genetics to identify larvae should help the process of foreign exploration, enabling the identification of field collected larvae, which often provide better host plant data than adults. Genetic sequence "barcodes" may also enable the use of cryptic species or biotypes for biological control and reduce the likelihood of mistakenly releasing the wrong species or biotype.
Technical Abstract: A field experiment was conducted to evaluate host plant specificity of the yellow starthistle rosette weevil, Ceratapion basicorne. Larvae infesting plants were preserved in 99% ethanol. Adult specimens of C. basicorne and four closely related species were identified using conventional morphological methods. A 731 bp fragment of cytochrome C oxidase I gene (COI) was sequenced from each specimen. Intraspecific variability ranged from 0.000 to 0.002, and was much less than interspecific distances, which ranged from 0.017 to 0.176. All larvae sequenced from the field study, clearly matched one of the five species, enabling us to unambiguously identify them. Our results confirmed that C. basicorne does not attack safflower in the field. COI results confirmed the Phylogenetic relationships among the five species that had previously been hypothesized based on morphological characters.