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Karuppannasamy Ashok

Publications and source records attributed to Karuppannasamy Ashok.

2 recordsLinked to original sources
PubMed2026

Molecular basis of Fenazaquin resistance in Polyphagotarsonemus latus revealed by transcriptome profiling and real-time validation.

The broad mite, Polyphagotarsonemus latus (Banks), is a highly polyphagous tarsonemid pest that causes severe damage to a wide range of agricultural and horticultural crops. The excessive and indiscriminate use of Fenazaquin, a mitochondrial electron transport inhibitor, resulted in the rapid development of resistance in P. latus. To elucidate the molecular mechanisms underlying acaricide resistance, a transcriptomic investigation was conducted on Fenazaquin-resistant (FEN-SEL) and susceptible (NBAIR-GR-TAR-01a) populations. The analysis identified putative genes involved in detoxification, including cytochrome P450 monooxygenases (CYPs), glutathione S-transferases (GSTs), choline and carboxyl esterases (CCEs), and ATP-binding cassette (ABC) transporters. Phylogenetic analysis revealed lineage-specific expansions of clan 3 CYPs, delta and acari-specific mu classes of GSTs, and ABCC, ABCG, and ABCH subfamilies of ABC transporters. Ten resistance-associated unigenes were validated using quantitative real-time PCR to assess gene expression patterns. The results showed significant upregulation of CYP4CL3, CYP4CF4, two delta-class GSTs, two CCEs belonging to clade J″, and two ABC transporters from subfamily C. However, CYP4725A2 and CYP4726A1 showed downregulation. These findings highlight the potential association of multiple metabolism-related gene families with Fenazaquin resistance and their possible contribution to the resistant phenotype. Overall, this study provides molecular insights into Fenazaquin resistance in P. latus, supporting the need for targeted resistance management strategies. Further research is warranted to evaluate the potential of these genes as molecular targets for sustainable broad mite management.

Acaricide↗
PubMed2026

Transcriptomic insights into thermal stress reveal physiological trade-off between thermal stress adaptation and reproductive investment in Spodoptera litura.

Spodoptera litura, a highly polyphagous lepidopteran pest, poses a major threat to agricultural productivity due to its remarkable adaptability to diverse environmental conditions. Although heat stress is known to trigger transcriptional reprogramming in insects, the molecular mechanisms underlying thermal stress responses in S. litura remain poorly understood. In the present study, fourth-instar larvae were exposed to acute heat stress (44 °C) and compared with control conditions (27 ± 1 °C) to investigate heat-induced transcriptional alterations affecting physiology and reproduction. High-quality RNA-Seq data achieved more than 80% mapping efficiency, with a total of 15,782 transcripts were identified. Transcriptome analysis of S. litura larvae showed 323 differentially expressed genes (DEGs), of which 262 genes were significantly upregulated and 61 were downregulated in heat-stressed larvae compared to the control group. The DEGs were associated with stress response, reproduction, signalling, proteostasis, detoxification, oxidative stress, metabolism, development, and chromatin regulation. Heat shock proteins genes, including HSP70, HSP90, and HSP27, together with co-chaperones such as TRET-1, STIP1, and Starvin, were strongly upregulated, indicating enhanced cellular protection against protein damage and oxidative stress under heat stress. Conversely, key reproductive and cell cycle-related genes, including BARR, CAPD2, FEO, CDK2 and MORULA, were significantly downregulated, suggesting reproductive impairment and developmental arrest. RT-qPCR validation corroborated the RNA-Seq findings, demonstrating a heat-induced physiological trade-off that prioritizes survival over reproduction. Consistent with these molecular responses, heat-stressed insects exhibited marked reproductive impairment, including significant reductions in gonadosomatic index, eupyrene sperm bundle count, mating frequency, mating success, female calling behaviour, copulation duration, fecundity, and egg fertility. Collectively, these findings provide comprehensive insights into the molecular basis of thermal adaptation in S. litura and demonstrate that acute heat stress compromises reproductive fitness while activating conserved stress-response pathways that promote short-term survival.

Animals↗