Impact of larval and adult feeding of Psylliodes chalcomera (Coleoptera: Chrysomelidae) on Centaurea solstitialis (yellow starthistle)

摘要

The flea beetle, Psylliodes chalcomera (Illiger) (Coleoptera: Chrysomelidae), is a promising candidate biocontrol agent for yellow starthistle, Centaurea solstitialis L., a weed of primary importance in the western USA. Two sets of trials were performed to evaluate the impact of insect feeding at larval and adult stages. In the first experiment, larval impact was assessed by inoculating different numbers of neonate larvae on bolting yellow starthistle plants. The impact was evaluated on fresh/dry biomass, size of plant, numbers of seed heads, seed production and germinability. The second experiment was focussed on the evaluation of adult feeding behaviour, including possible gregarious aspects, which could result in a relative increase of damage onyellow starthistle. The larval transfer test showed a significant impact of larval feeding on yellow starthistle, although limited to seed production. P. chalcomera adult feeding was negatively influenced by the presence of other individuals on the samesubstrate. On the other hand, the individual feeding rates, especially for females, suggest a potential defoliation impact. Comparing the outcome of both experiments with the infestation rates observed in the field, P. chalcomera shows potential to damage yellow starthistle, although more studies are needed to assess the impact of such damage.