Genomes reveal global lineages of the citrus psyllid

An analysis of 133 mitochondrial genomes of Diaphorina citri identified two lineages with strong genetic differentiation, one Asian and the other American. The study found 32 fixed nucleotide variants between the groups. These sites can serve as molecular markers to trace the origin of insects in quarantine and monitoring actions.

Diaphorina citri transmits Candidatus Liberibacter asiaticus, a bacterium associated with huanglongbing. Researchers compiled 77 previously published genomes, 13 new genomes from Hunan, China, and 43 mitogenomes obtained from metagenomic data. The sample included Asia, the Americas, and Africa.

The Asian lineage comprised 91 samples, including one from Uruguay. The American lineage comprised 42 samples, including one from Pakistan. The differentiation between the two lineages reached an FST of 0,560, with p less than 0,001.

In the Asian group, eight samples from the Yunnan–Guizhou Plateau formed a genetically distinct cluster. The plateau population showed an FST of 0,130 compared to the lowland populations and lower nucleotide diversity. Two fixed differences in the trnG and rrn16 genes emerged as candidate markers for this lineage.

The data also points to Southeast China as a possible center of expansion after colonization. The small sample size in Southeast Asia prevents defining a definitive global origin.

Scientists emphasize the need to validate the markers in samples from other regions before use in quarantine, surveillance, or management programs (doi 10.3390/insects17090917).