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Whitefly Bemisia tabaci (Gennadius) is an important pest of cotton in India. The study of taxonomic diversity and its distribution on cotton is lacking. Such studies are necessary to identify the genetic groups of B. tabaci and its distribution on cotton in India. The proper identification of genetic groups and their distribution, which, ultimately, can lead to the timely development and utilization of management practices. The current study was undertaken to explore the genetic diversity and phylogeographic structure of B. tabaci from all the three major cotton growing zones representing different agro-climatic conditions of India. 290 partial mitochondrial Cytochrome Oxidase I (mt COI) sequences of whitefly population of six major cotton-growing states covering 22 districts were used in the analysis. Phylogenetic analysis revealed the presence of two monophyletic clades, Asia I and Asia II1 genetic groups represents South-Central India and North India respectively. Asia II1 is found more predominately distributed in the cotton leaf curl virus (CLCuV) disease-prone north Indian cotton-growing states. Higher genetic divergence (16.8–19.2%) was observed between the populations of Asia I and Asia II1 genetic group. Genetic differentiation analysis confirmed the phylogeographic structure of B. tabaci as isolated by distance. Our results in mapping the distribution of genetic groups in cotton ecosystems paved the way for the further studies and formulation of area-wide management practices for cotton whitely in India. [ABSTRACT FROM AUTHOR]

The insecticidal and phytotoxicity activities of oils from castor (Ricinus communis), pongamia (Pongamia glabra), sesame (Sesamum indicum), neem (Azadirachta indica) and neem based formulations in combination with a detergent Powder as a surfactants (0.1%) were studied against adults of Bemisia tabaci at their peak activity period during 2016–17 and 2017–18 seasons under laboratory and field conditions. Among the oils, castor oil caused a reduction of whitefly populations by 55.4 & 64.2 and 40.5 & 42.8% under laboratory and field conditions, respectively during both the years, pongamia oil 58.4 & 51.7 and 44.9 & 39.2%, sesame oil 45.5 & 56.4 and 30.8 & 36.9%. Neem oil and its formulated products were reported to be comparatively less effective in reduction of whitefly population after chemical treatments i.e. difenthiauron 50 WP (76.2 & 81.5 and 63.5 & 55.2% under laboratory and field conditions, respectively). Phytotoxicity observed after application of recommended doses of castor, pongamia, sesame and neem oil and its formulated products did not cause any problem on tender cotton leaves. The detergent based solutions were difficult to mix and oily layers appeared after mixing, hence mixing the oils and detergent solutions with sticker Triton-X-100 @1.0 ml/l is more effective and easy to apply on cotton plants. [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]

[Display omitted] • EPF varied in mycelial growth, sporulation, nymphal mortality of Bemisia tabaci. • New record of Fusarium verticillioides infection on Bemisia tabaci. • Bioefficacy index considered mycelial growth, sporulation, nymphal mortality by EPF. • BI proved as an effective predictor for selecting EPF for field efficacy. • MT-4511, IT-10499 showed higher efficacy against B. tabaci nymphs than insecticides. • These could be utilized as eco-friendly management of whitefly and CLCuD in cotton. The whitefly , Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is becoming a serious problem on Bt cotton. It causes enormous crop loss through its direct feeding and as a vector of cotton leaf curl virus. Chemical-dependent management is harming the environment and increased insecticide resistance is often observed in the fields. Identification of most virulent strains of entomopathogenic fungi (EPF) is essential to serve as an important component of an IPM program for management of B. tabaci. Compared to B. tabaci adults, the nymphal stage is reported to be more susceptible to entomopathogens, and targeting nymphs also helps vector management. We evaluated the bioefficacy of EPF and chemical pesticides against nymphs of B. tabaci on Bt cotton under polyhouse and field conditions. The bioefficacy index (BI) was considered as a mechanism to select the most effective EPF strains for field evaluation. The highest nymphal mortality under polyhouse conditions was recorded for Metarhizium anisopliae NA-01299 (86.7%), Beauveria bassiana MT-4511 (85.1%), Cordyceps javanica IT-10498 (81.1%), IT-10499 (81%), and B. bassiana NA-0409 (78.2%) relative to other EPF strains, spiromesifen (69.6%), buprofezin (62.2%) and pyriproxyfen (52.7%) at 7-days-post-spray treatment (DAS). However, among all the EPF, the highest BI was recorded in C. javanica IT-10499 (77%), IT-10495 (75.4%), Fusarium verticillioides IT-10493 (74.6%), and B. bassiana MT-4511 (73.1%). The pooled data of two-year field trials (2017–18 & 2018–19) revealed that the highest nymphal mortality was recorded for MT-4511 (85%), IT-10499 (83.2%), and pyriproxyfen 10% EC (78.6%) at 7-DAS. The BI-based selection of EPF proved to be a useful predictor of field efficacy. A sequential spray of the selected EPF would be a vital approach for resilient and sustainable integrated management of the B. tabaci nymphal population under field conditions. [ABSTRACT FROM AUTHOR]

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a serious pest of cotton that inflicts huge economic losses. Excessive use of chemical pesticides for its management causes environmental pollution and pesticide resistance. Six bioassay methods and ten entomopathogenic fungal strains (EPFs) were evaluated to find out the suitable bioassay method and the most virulent strain(s) for management of B. tabaci under laboratory and polyhouse conditions. The highest tenderness and survival period (> 30 days) of the leaves and increasing trend in nymphal mortality was recorded in a new modified polyhouse bioassay method (NMPBM). NMPBM was found to be effective, simpler, and less labor intensive for evaluating large numbers of EPF strains. Twelve newly isolated EPF strains were characterized based on their morphological and molecular characteristics. The highest whitefly nymphal mortality (at 107 conidia ml−1) was recorded by Beauveria bassiana (Bb)-4511 (95.1%), Bb-4565 (89.9%), and Metarhizium anisopliae-1299 (86.7%) at the seventh day post inoculation. However, the overall bioefficacy index was higher in Bb-4511 (78.1%), Cordyceps javanica (Cj)-102 (77.0%), and Cj-089 (75.4%) than other EPF strains. The lowest values of LC50 and LC90 were with Cj-089 and Bb-4511. The field deployment of effective formulation of these most virulent EPF strains might be helpful for managing B. tabaci populations and CLCuD incidence under insecticide resistance management programs. [ABSTRACT FROM AUTHOR]