The silverleaf whitefly, Bemisia tabaci (Gennadius, Hemiptera: Aleyrodidae), is a major threat to field and horticultural crops worldwide. Persistent use of insecticides for the management of this pest is a lingering problem. In the present study, the status of sensitivity of B. tabaci to two neonicotinoids, imidacloprid and thiamethoxam, was evaluated. The expression pattern of two cytochrome P450 (cyp) genes and changes in the relative amount of symbionts in insecticide-treated B. tabaci were also assessed. Quantitative PCR (qPCR) studies indicate that the CYP6CM1 and CYP6CX1 genes were always expressed higher in imidacloprid-treated whitefly, suggesting a correlation between gene expression and the insect’s ability to detoxify toxic compounds such as insecticides. In addition, the thiamethoxam-treated population harbored higher Portiera and lower Rickettsia titers, whereas the imidacloprid-treated population harbored more Rickettsia at different time intervals. Interestingly, we also examined that an increase in exposure to both the insecticides resulted in a reduction in the mutualistic partners from their insect host. These differential responses of endosymbionts to insecticide exposure imply the complex interactions among the symbionts inside the host insect. The results also provide a deeper understanding of the molecular mechanism of resistance development that might be useful for formulating effective management strategies to control B. tabaci by manipulating symbionts and detoxifying genes.

Fall armyworm (FAW), Spodoptera frugiperda a recent invasive pest in India is reported to cause significant damage by feeding voraciously on maize and other economic crops from tropical to temperate provinces. It is becoming an arduous challenge to control the pest as it can survive in a wide range of temperature conditions and is already said to develop resistance towards certain insecticides. The small Heat shock proteins (hereafter, sHsps) are known to play an important role in adaptation of insects under such stress conditions. Our present study involved characterization of the three sHsps genes (sHsp19.74, sHsp20.7 and sHsp19.07) which encoded proteins of about 175, 176 and 165 amino acids with a conserved α-crystalline domain. Phylogenetic analysis of deduced amino acid sequences of the three genes showed strong similarity with the other lepidopteran sHsps. The effect of different growth stages on the expression profile of these stress proteins has also been studied and the Quantitative real time PCR (qRT-PCR) analysis revealed that the transcript level of sHsp19.07 and sHsp20.7 were significantly upregulated under extreme heat (44 °C) and cold (5 °C) stress. However, sHsp19.74 responded only to heat treatment but not to the cold treatment. In addition, the expression profile of all three sHsps was significantly lower in the larval stage (5th instar). Chlorantraniliprole treatment resulted in maximum expression of sHsp19.07 and sHsp20.7 after 12hr of exposure to the insecticide. Meanwhile, the same expression was observed after 8hr of exposure in case of sHsp19.74. These results proved that the sHsp genes of S. frugiperda were induced and modulated in response to abiotic stress, thus influencing the physiological function leading to survival of FAW in diversified climate in India.

Acquisition of plant viruses is known to exert various effects on vectors’ developmental biology. Pentalonia nigronervosa is the only known vector of banana bunchy top virus (BBTV), which is an economically detrimental virus infecting banana cultivars all over the world. In the present study, the developmental biology of viruliferous (Vr) and non-viruliferous (NVr) aphids was compared, with a marked reduction noted in the lifespan of aphids upon acquisition of BBTV. Among all the environmental parameters temperature is an important determinant of an insect’s abundance and geographical distribution. Temperature susceptibility of P. nigronervosa was scrutinized by comparing the mortality percentage and differential expression pattern of three heat shock proteins (Hsps; Hsp40, Hsp70, and Hsp90) at the mRNA level between NVr and Vr aphids. After exposure to different temperature stress (5 °C, 15 °C, 38 °C and 25 °C as control) highest mortality of Vr aphids were recorded at 5 °C. Analysis of expression levels of Hsp genes using qPCR showed that both cold and heat shock treatment stimulated higher expression of the three Hsps at various rates in Vr than NVr aphids.. Finally, the effect of temperature stress on the BBTV titer level and their transmission by P.nigronervosa was determined by absolute quantification. The transmission efficiency along with the virus titer was found to be the lowest at 15 °C compared to 38 °C. Overall, our results provide a novel insight into the intricate interaction between aphid fitness and thermal stress concerning the acquisition and transmission of BBTV, which could be a roadmap for the future epidemiological control system.

Butterfly pea (Clitoria ternatea), also known as Asian pigeonwings is a perennial herbaceous plant belongs to the Fabaceae family has a great source of natural food colorants and antioxidants (Suarna et al., 2021). It is a multipurpose forage that produces bioactive compounds, acts as a cover crop and improves soil fertility through nitrogen fixation (Gomez et al, 2003). Rhynchosia Yellow Mosaic Virus (RhYMV) which is transmitted by the whitefly (Bemisia tabaci) was first reported from Pakistan in leguminous weed least snoutbean, Rhynchosia minima (Illias et al., 2009). There is no record on the infection of RhYMV in butterfly pea in India or anywhere in the world. In 2022 and 2023, 250 whole butterfly pea plants were collected from few home stead gardens from ten districts (Alipurduar, Darjeeling, Jalpaiguri, Cooch Behar, Malda, Nadia, Birbhum, Hoogly, Purulia and East Midnapore) within the West Bengal province in India, showed extensive yellow mosaic symptoms and distorted flower with bleaching of blue color of petals (Supplementary file 1). The detection of the virus was carried out in the Advanced Plant Virus Diagnostic Centre, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India. DNA extraction was conducted by using plant genomic DNA isolation kit (Sigma-Aldrich, St Louis, USA). The concentration and purity of DNA samples were determined by DeNovix-DS11 spectrophotometer. The presence of the virus was confirmed through polymerase chain reaction (PCR) using begomovirus-specific degenerated primer (Li et al., 2004) followed by RhYMV specific primer (Ilyas et al., 2009). Out of total 250 test samples, 241 were positive for begomovirus specific degenerated primer (96.40%) and out of 241 positive samples, 178 plants were positive to RhYMV specific primer which confirmed 73.85% samples infected to RhYMV. After confirmation of the virus whole genome obtained through Rolling Circle Amplification (RCA) (TempliPhi 100 Amplification Kit, Cytiva) followed by sequencing. After assembled and analyzing the data in CLC Genomics version Workbench 21.0.5 (Matvienko, 2015) whole genome of DNA-A sequence was depositd in the NCBI GenBank database (accession number- PP735226). The BLASTn analyses of the sequence indicated that the isolate from West Bengal, had the 95.44% identity (2616 bp out of 2741 bp) with a RhYMV isolate from snoutbean (Rhyncosia minima) from Pakistan (FM208847). For pathogenecity test (Supplementary file 2), whiteflies reared under polyhouse conditions, acquired the virus from infected plants over 24 hrs (AAP) then allowed viruliferous whiteflies to inoculate the healthy plants for 24 hrs (IAP) and symptoms were monitored under an insect-proof cage. Around two weeks of post- inoculation, all Clitoria plants exhibited mild yellow mosaic symptoms. At 28 dpi, bright yellow to green mosaic appearance, downward curling, and wrinkling of the leaves accompanied with thin tendril with severely distorted flowers were seen which was similar to the samples collected from the different districts. For further confirmation, the infected samples tested positive for RhYMV specific primer were subjected to RCA and whole genome sequencing and found same lineage of RhYMV (accession number- PQ360900). To the best of our knowledge, this is the first report on the incidence of RhYMV in butter fly pea which is to be considered as a new host of RhYMV in India could also act as a reservoir of the virus for further spread to other leguminous plants.