KOREASCHOLAR

Current investigations provide a comprehensive understanding of the occurrence and biodiversity of plant-parasitic nematodes (PPNs) in the major citrusproducing regions of Jeju Island, South Korea. Our survey identified five genera and five species of PPNs from 82 infested Citrus unshiu field samples collected across 116 sites in the Jeju provinces. Community analysis revealed the highest prevalence of PPNs (39.02%) at Namwon-eup, significantly driven by Tylenchulus semipenetrans, followed by Paratylenchus sp., Helicotylenchus sp., Meloidogyne sp., and Pratylenchus sp. Data indicate that all 82 sites were infested with T. semipenetrans (70.68%), marking a considerable increase in prevalence compared to previous surveys and posing a significant threat to citrus cultivation. The study results also demonstrate the influence of soil type on PPNs communities, revealing correlations between soil texture and nematode diversity. Citrus orchards cultivated in black clay loam soil exhibited significant PPN infestations. Overall, the PPN survey underscores the economic importance of monitoring citrus nematode infection rates and maintaining economic threshold levels in citrus production. It also emphasizes the need for developing effective management strategies to control PPNs, which are essential for maintaining crop yield and ensuring agricultural sustainability.

Abstract
1. INTRODUCTION
2. MATERIALS AND METHODS
    2.1. Survey site and soil sampling
    2.2. Nematode extraction
    2.3. Morphometric and molecularidentification of PPNs
    2.4. Assessment of PPNs communitystructure
3. RESULTS
    3.1. Occurrence and distribution of PPNs
    3.2. Community structure and the prevalenceof PPNs in citrus orchards
    3.3. Molecular characterization of PPNs
4. DISCUSSION
    4.1. Occurrence and distribution of PPNs incitrus field
    4.2. Economic threshold of T. semipenetrans
    4.3. Community structure and the prevalenceof PPNs in citrus orchards
5. CONCLUSION
CRediT authorship contribution statement
Declaration of Competing Interest
ACKNOWLEDGEMENTS
SUPPLEMENTARY MATERIALS
REFERENCES

• Karthi Natesan(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea)
• Sekeun Park(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea)
• Hyoung-Rai Ko(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea)
• Eunhwa Kim(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea)
• Sohee Park(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea)
• Byeong-Yong Park(Crop Protection Division, National Institute of Agricultural Sciences, RDA, Wanju 55365, Republic of Korea) Corresponding author