Publications by CPCRI Staff

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Browsing Publications by CPCRI Staff by Author "A. Josephrajkumar"

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    Insights into the incidence, severity and morphometrics of the invasive Rugose Spiralling Whitefly Aleurodicus rugioperculatus Martin in coconut belts of Tamil Nadu, India
    (2024) P. Logeshkumar; R. Nalini; A. Josephrajkumar; P. Chandramani; M. L. Mini; R. Durai Singh; K. Venkatesh; M. Murugan
    Rugose Spiralling Whitefly (RSW) (Aleurodicus rugioperculatus Martin; Aleurodidae: Hemiptera) began invading India in 2016 from Southern Peninsula, later expanded to several other states of the country. As a result, India now considers RSW to be a serious invasive insect pest on coconut. To understand its severity in Tamil Nadu, an extensive field survey was taken up, which revealed that the RSW abundance was in decreasing trend in Cauvery Delta Zone followed by Southern zone, High Rainfall zone and Western zone. The frond damage was lowest in Southern zone (Madurai, 14.43%) and statistically on par with Western zone (Coimbatore, 28.76%) whereas highest frond and leaflet damage was observed in Cauvery Delta zone (Pudukottai, 82.3 and 72.66% respectively). The aphelinid parasitoid, Encarsia guadeloupae Viggiani adult’s emergence was high in Coimbatore district with a parasitization rate of 93.25 per cent. In morphometric studies, many morphological parameters measured in A. rugioperculatus adult male and female were high in Pudukkottai population. Score plot analysis of both sexes of A. rugioperculatus clearly showed that no biotype existed. The nucleotide sequence of RSW was deposited in GenBank as OP 295,073 which had > 98 per cent similarity with those DNA sequences submitted in NCBI database OP0295073, OP414609 and MK 883,219. Five years down the infestation of RSW on coconut, the severity has been reduced drastically with the subsequent buildup of the parasitoid E. guadeloupae. Thus conserving E. guadeloupae through the establishment of “banker plants” and refraining from insecticide spraying can effectively suppress RSW in the long term.
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    Validation of suitable reference genes for gene expression studies in rugose spiraling whitefly (Aleurodicus rugioperculatus Martin) under various experimental conditions
    (2026) A. A. Sabana; M. K. Rajesh; Jasmin Habeeb; M. Sujithra; A. Josephrajkumar
    crops, including coconut. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is a fundamental and widely used technique in genomic research, particularly for analyzing gene expression levels with high sensitivity and specificity. One of the most critical factors influencing the accuracy and reliability of qRT-PCR results is the choice of internal reference genes, also known as housekeeping genes. These genes are used to normalize the expression levels of target genes. However, the lack of studies validating reference genes in A. rugioperculatus significantly restricts the accurate application of qRT-PCR for gene expression analysis. This study aims to identify suitable reference gene(s) across different biotic and abiotic conditions in A. rugioperculatus. The expression stability of 14 reference genes (18S rRNA, GST, HSP90, GAPDH, RPS17, actin, RPL13, NADH, ETF-QO, EF1α, UBQ, β-TUB, peptidylprolyl isomerase A, and Myosin L) was analyzed using five different computational programs, such as geNorm, NormFinder, BestKeeper, Comparative ΔCT, and RefFinder. The findings suggested that the optimal combinations of reference genes in A. rugioperculatus were 18S rRNA and NADH for different developmental stages, 18S rRNA and EF1α for different sexes and temperatures, and RPL13 and 18S rRNA for starvation conditions. This study presents the first report of stable reference genes for normalizing qRT-PCR analysis in A. rugioperculatus, laying the foundation for future expression studies and RNAi-based management of the rugose spiraling whitefly.