Unbinding the bindweed psyllid (<i>Bactericera maculipennis</i> [Hemiptera: Triozidae]) from its <i>Convolvulus</i> host exposes it to a novel bacterial symbiont

Psyllids (Hemiptera: Psylloidea) are herbivores that feed and reproduce on narrow subsets of hosts within a few related genera. During surveys of Solanum umbelliferum (Eschsch) (Solanaceae), we collected multiple life stages of Bactericera maculipennis (Crawford), a species exclusively associated with bindweeds (Convolvulaceae). We hypothesized that B. maculipennis has expanded its host range to include this solanaceous host. To test this, we quantified egg to adult development time on S. umbelliferum, 2 other solanaceous hosts, and Convolvulus arvensis L., the most suitable host for B. maculipennis in North America. B. maculipennis failed to develop on additional solanaceous hosts but developed significantly faster on S. umbelliferum than on C. arvensis. We also sampled for B. maculipennis at 27 S. umbelliferum populations and collected 24 individuals directly from S. umbelliferum plants. We confirmed all individuals are B. maculipennis and found that 10/24 were infected with the plant pathogen 'Candidatus Liberibacter solanacearum' (CLso), which is transmitted by the potato psyllid, B. cockerelli (Šulc). Half of infected individuals harbored CLso haplotype B, which is dominant in crops, but rare in S. umbelliferum. The other 50% harbored CLso haplotype Sumb2, previously documented in S. umbelliferum, but never in crops. Our results suggest that the host range of B. maculipennis has expanded to include a key wild host plant of B. cockerelli. This may create opportunities for exchange of multiple haplotypes of CLso between these 2 species, possibly facilitating the emergence of CLso variants as pathogens of plants in the Convolvulaceae.