Population genetic structure of Diaphorina citri Kuwayama (Hemiptera: Liviidae): host-driven genetic differentiation in China

Abstract

The Asian citrus psyllid Diaphorina citri Kuwayama is a major pest in citrus production, transmitting Candidatus Liberibacter asiaticus. It has spread widely across eastern and southern China. Unfortunately, little is known about the genetic diversity and population structure of D. citri, making pest control difficult. In this study, nine specifically developed SSR markers and three known mitochondrial DNA were used for population genetics study of D. citri using 225 samples collected from all 7 distribution regions in China. Based on the SSR data, D. citri was found highly diverse with a mean observed heterozygosity of 0.50, and three subgroups were structured by host plant: (i) Shatangju, NF mandarin and Ponkan; (ii) Murraya paniculata and Lemon; (iii) Citrus unshiu, Bingtangcheng, Summer orange and Navel. No significant genetic differences were found with mtDNA data. We suggested the host-associated divergence is likely to have occurred very recently. A unimodal distribution of paired differences, the negative and significant Tajima’s D and Fu’s FS parameters among mtDNA suggested a recent demographic expansion. The extensive citrus cultivation and increased suitable living habitat was recommended as a key for this expansion event.

Occurrence of prophage and historical perspectives associated with the dissemination of huanglongbing in mainland China

“…Jiangxi, Zhejiang and Hunan are relatively newly invaded areas and the CLas populations there have greater prophage‐associated gene diversity. Greater genetic diversity was also detected in ACP in these provinces (Meng et al , ). This strongly suggests that CLas in these areas has experienced a series of recent population expansion events through introductions of infected seedlings from multiple diseased provinces (Huang, ; Ganzhou Citrus Huanglongbing Research Group, unpublished investigation report on occurrence and distribution of citrus huanglongbing in 1979; Institute of Subtropical Crops, Zhejiang Academy of Sciences, unpublished investigation report of citrus huanglongbing in 1982), multiple invasions of ACP, the recent rapid diversification of citrus varieties and extensive commercial cultivation of citrus trees in recent years (Meng et al , ).…”

Population diversity of Diaphorina citri (Hemiptera: Liviidae) in China based on whole mitochondrial genome sequences

“…Although sequences of cox1 have commonly been used in phylogenetic studies of ACPs, our whole mitogenome sequence analyses showed that resolution of cox1 sequences is limited for ACP. In fact, no diversity was detected using cox1 among Chinese ACP samples in this study (Fig.…”

“…S2a). A recent study reported the detection of SNPs in cox1 from ACPs collected in China . Reasons for the differences remain to be studied.…”

“…To the best of our knowledge, current morphological information has failed to describe ACP variation. However, recent DNA sequence technology does distinguish between populations . Because of the relatively small genome sizes, low levels of recombination, and variable evolution rates, in recent years mitogenome sequences have gained importance in comprehensive evolutionary and population studies of insects .…”

“…Because of the relatively small genome sizes, low levels of recombination, and variable evolution rates, in recent years mitogenome sequences have gained importance in comprehensive evolutionary and population studies of insects . Partial sequences of the cytochrome oxidase 1 gene ( cox1 ) in the mitogenome have been used to study ACP population diversity from different geographical regions . As technology advances, whole ACP mitogenome sequences (completely encircled or not completely encircled) can be acquired through next‐generation sequencing (NGS) and analyzed .…”