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Amrasca biguttula biguttula(Ishida), the cotton leafhopper, is a polyphagous insect pest of Asia and Southeast Asian countries. We sequenced a mitochondrial COI gene fragment from 67 individuals of cotton leafhopper collected from 7 major cotton growing states of North, Central, and South India. Genetic divergence analysis of leaf hopper population across India confirmed the presence of single species. Thirty haplotypes, in total, were determined across different regions of India. While population from North India was dominated by single haplotype, the south and central Indian populations show dispersion of different haplotypes across the region. The neutrality test rejection for the north Indian population also suggests population expansion. The genetic differentiation and gene flow analysis together confirmed the phylogeographic structure of theA. biguttula biguttulaIshida as isolated by distance. [ABSTRACT FROM AUTHOR]

Background: Insecticidal proteins from the Bacillus thuringiensis (Bt) marks the genetically modified cotton crop that was commercialized in India in March 2002 for the control of lepidopteron bollworms. Despite organized initial control, the pink bollworm (PBW), Pectinophora gossypiella (Saunders), adapted itself to cry toxins resulted in field control failures in 2016 and 2017. The present study was designed to understand the survival and development of PBW populations differing in susceptibility to Cry toxins on Bt and non-Bt plants. Results: For assessment of infestation, populations were collected from different cotton growing states. Per cent infestation of flowers and green bolls in the study areas were in the range of 3.09–29.26 and 36–91.20% for flowers and green bolls, respectively. Among different locations highest magnitude of resistance to Cry1Ac (371.8-fold) and Cry2Ab (4214.3-fold) was spotted in late season populations of Rajkot collected from bolls. Further, in order to confirm field level resistance of surviving larvae on high and low concentrations of Cry toxins, larvae were pooled and subjected to boll bioassays. Results revealed that, none of the larvae from susceptible populations survived on BGII bolls. Although, the same populations showed a survival of 38 and 32%, which led to 80% locule damage on non-Bt cotton. Maximum survival (32%) and locule damage (70%) was observed for Maharashtra (F-H) Cry2Ab and Gujarat (B-H) Cry2Ab populations recorded 36% survival and 70% mortality, respectively, on BGII cotton and 58.33% survival and 60% locule damage on non-Bt cotton, respectively. Populations derived from survivals on low concentrations produced the lowest survival and locule damage on Bt cotton. Maximum number of mines on epicarp (2.4 mines/boll) was recorded by susceptible population on NBt cotton. Green bolls of Bt and NBt cotton did not differ in the number of mines. Conclusion: It was concluded that none of the larvae from susceptible populations survived on BGII bolls. Although, the same populations showed a survival of 38 and 32%, which led to 80% locule damage on non-Bt cotton [ABSTRACT FROM AUTHOR]

Cotton leaf curl disease (CLCuD) ranks top among all endemic diseases transmitted by whitefly (Bemisia tabaci) affecting cotton (Gossypium hirsutum) causing severe economic losses to the cotton growers in the Indian subcontinent. For its effective management, robust tools for detection are a prerequisite and it is important to diagnose the virus titre in early stage of infection in plants as well as in the disease transmitting vector. Considering the limitations in current PCR-based techniques we have standardised rapid and sensitive Loop Mediated Isothermal Amplification (LAMP) protocol for the diagnosis of cotton leaf curl virus (CLCuV) in cotton leaves and in its transmitting vector whitefly. Perhaps, this is the first report of use of LAMP tool for rapid diagnosis of CLCuV in cotton and its transmitting vector the whitefly. Further, the colorimetric detection for diagnostic simplicity of amplified LAMP product by using different dyes lead to enhanced applicability of this technique in the field of disease diagnostics. The merit of present study is that the diagnostic failure of PCR and LAMP due to low virus titre in the infected leaf has been circumvented through the combination of rolling circle amplification (RCA) with LAMP. Thus RCA-LAMP can be an option for ultra-sensitive detection of samples with low virus titre. The potential applications of this advanced diagnostic tool in laboratory research on diagnosis of CLCuV, an important viral pathogen of cotton have been discussed. • This is the first report on diagnosis of CLCuV from cotton plant and its transmitting vector whitefly by using LAMP technique. • The colorimetric detection by using different dyes lead to enhanced applicability of this technique in the field of diagnostics. • RCA-LAMP can be an option for ultra-sensitive detection of samples with low virus titer. • This advance diagnostic protocol can be effectively utilized in the laboratory and quarantine diagnosis for CLCuV. [ABSTRACT FROM AUTHOR]