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Beauveria bassiana (Bal.-Criv.) is an important entomopathogenic fungus being used for the management of various agricultural pests worldwide. However, all strains of B. bassiana may not be effective against whitefly, Bemisia tabaci, or other pests, and strains show diversity in their growth, sporulation, virulence features, and overall bioefficacy. Thus, to select the most effective strain, a comprehensive way needs to be devised. We studied the diversity among the 102 strains of B. bassiana isolated from 19 insect species based on their physiological features, virulence, and molecular phylogeny, to identify promising ones for the management of B. tabaci. Strains showed diversity in mycelial growth, conidial production, and their virulence against B. tabaci nymphs. The highest nymphal mortality (2nd and 3rd instar) was recorded with MTCC-4511 (95.1%), MTCC-6289 (93.8%), and MTCC-4565 (89.9%) at a concentration of 1 × 106 conidia ml−1 under polyhouse conditions. The highest bioefficacy index (BI) was in MTCC-4511 (78.3%), MTCC-4565 (68.2%), and MTCC-4543 (62.1%). MTCC-4511, MTCC-4565, and MTCC-4543 clustered with positive loading of eigenvalues for the first two principal components and the cluster analysis also corresponded well with PCA (principal component analysis) (nymphal mortality and BI). The molecular phylogeny could not draw any distinct relationship between physiological features, the virulence of B. bassiana strains with the host and location. The BI, PCA, and square Euclidean distance cluster were found the most useful tools for selecting potential entomopathogenic strains. The selected strains could be utilized for the management of the B. tabaci nymphal population in the field through the development of effective formulations. Key points: • 102 B. bassiana strains showed diversity in growth and virulence against B. tabaci. • Bioefficacy index, PCA, and SED group are efficient tools for selecting potential strains. • MTCC-4511, 4565, and 4543 chosen as the most virulent strains to kill whitefly nymphs. [ABSTRACT FROM AUTHOR]

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]

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]

In the process of development of insect resistant transgenic plants and also to evaluate the consistency in expression of the toxin under greenhouse and field conditions, immunological and bioassays are commonly used. The assay being described in this report, is based on the high levels of sensitivity of a cotton leaf feeding insect, the semilooper, Anomis flava (Fabricius) to Cry toxins (Cry1Aa, Cry1Ab and Cry1Ac). The assay is sensitive, quick and reproducible. Cry1Ac was the most toxic followed by Cry1Ab and Cry1Aa. LC[sub 50]s of the three toxins on first instar larvae ranged from 0.79-6.08 ng cm[sup -2] of leaf. LC[sub 50]s of Cry1Ac for the fourth instar larvae ranged from 12.91-21.14 ng cm[sup -2] while LC[sub 50]s for Cry1Aa and Cry1Ab were in the range 53.0-138 ng cm[sup -2]. The fiducial limits (at 95% probability) of the probit assay data indicated that there was no difference in response between the three different populations to each of the three toxins. The data from all assays were pooled for each of the three toxins separately and subjected to regression analysis to obtain a cumulative log dose response for first and fourth instar larvae. These can be used as standard curves to quantify toxin expression in plants based on mortality response of either first or fourth instar A. flava larvae. Apart from being used to detect expression in putative Bt cotton transgenic plants, the assay can also be used to follow the activity of Cry toxins in transgenic cotton plants in the field during the growing season. [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]

Pink bollworm, Pectinophora gossypiella (Saunders) infestation on Bt cotton is a major concern to cotton production in India. The genetic diversity and phylogeographic structure of the insect in light of PBW resistance needs to be revisited. The objective of this study was to identify different haplotypes of pink bollworm and their distribution in India. To achieve this we studied the population structure in 44 cotton growing districts of India. The partial mitochondrial COI sequence analyses of 214 pink bollworm populations collected from 44 geographical locations representing 9 cotton growing states of India were analysed. Genetic diversity analysis exhibited presence of 27 haplotypes, among them Pg_H1 and Pg_H2 were the most common and were present in 143 and 32 populations, respectively. Distributions of pairwise differences obtained with partial COI gene data from the overall Indian populations are unimodal, suggesting population expansion in India. Significant neutrality test on the basis of Tajima' D and Fu's Fs presented a star-shaped haplotype network together with multiple haplotypes. The unimodal mismatch distribution, rejection of neutrality test with significant negative values supported the theory of demographic expansion in cotton pink bollworm populations in India. Genetic data not only provides us with a perspective of population genetics, but also that the two populations of pink bollworm, those occurring early in the season are genetically close to the late season populations with respect to their partial CO1 region. Resistance to Cry toxins does not seem to have had an impact on this region of the mt DNA in populations of pink bollworm. [ABSTRACT FROM AUTHOR]

Tobacco Streak Virus (TSV) belongs to the genus Ilarvirus of the family Bromoviridae an emerging pathogen posing threat to the crop species worldwide. Identification of symptoms due to TSV infection by visual observation of plants often results in misdiagnosis as symptoms produced by this virus can match with those reflecting physiological and nutritional disorders affecting cotton. Development of diagnostic tools with rapidity will have immense role to play in detection and management of the emerging virus. The protocol for rapid diagnosis of TSV infected samples by using Reverse Transcription-Loop Mediated Isothermal Amplification (RT-LAMP) was optimised and this is the first report of its use for diagnosis of TSV on cotton and Soybean. The colorimetric detection for diagnostic simplicity of amplified RT-LAMP product by using different dyes lead to enhanced applicability of this technique. The RT-LAMP diagnostic tool can be utilized not only for laboratory research but also for quarantine and field diagnosis of this important emerging pathogen affecting cotton. [ABSTRACT FROM AUTHOR]

Bemisia tabaci, a vector of cotton leaf curl virus disease, is among the most devastating pests causing huge economic losses due to reduced cotton yield and quality. The excessive use of chemical pesticides causes insecticide resistance. Entomopathogenic fungi (EPFs) have a role as mycoinsecticides. The combined use of these insecticides is a promising pest-control option to minimize adverse chemical effects. Thus, we have evaluated 10 EPFs under polyhouse conditions for their virulence against whitefly nymphs and their compatibility with chemical and botanical insecticides. The highest overall biological efficacy index was recorded with Ij-102, followed by Bb-4511, and Ij-089. An in vitro compatibility study was conducted to evaluate the effect of botanical and chemical pesticides on mycelial growth and spore production using the poisoned food technique. The effect of pesticides on the reduction of mycelial growth and conidial production ranged from -169 to 94.1% and -25.6 to 87.6%, respectively. However, Ij-089, Ij-102, Ma-1299, and Bb-4511 were found to be the most compatible with the chemical and botanicals evaluated. Comparatively, spiromesifen, diafenthiuron, buprofezin, pyriproxyfen, and flonicamid were more compatible with EPFs at half doses, as compared to the other chemical pesticides, namely imidacloprid, fipronil, profenophos, and triazophos. These results might provide the basis for future work and indicate that applications of EPFs showing the best virulence and compatibility have the maximum likelihood for the management of B. tabaci in the field in an integrated pest management system. [ABSTRACT FROM AUTHOR]

The suppressive effects of microbial inoculants on cotton seedling mortality were assessed in Rhizoctonia solani-infested soil. Per cent mortality ranged from 16 to 32 (60-120 days after sowing, DAS) and significant differences were recorded at 120 DAS, especially after drenching with compost tea of Azotobacter sp. and Anabaena torulosa-Trichoderma viride-biofilmed formulations. The activity of hydrolytic enzymes was reduced in diseased root tissues due to a majority of the microbially inoculated treatments, compared with healthy root tissues. Per cent changes in the amounts of glomalin-related soil proteins ( GRSPs) were 2 to 85% greater than those of the uninoculated experimental controls. These microbial inoculants altered the rhizosphere bacterial communities as evident from the Denaturing gradient gel electrophoresis ( DGGE) banding patterns and, also reduced the population of R. solani. While the copy numbers of the internal transcribed spacer ( ITS) gene of R. solani in the uninoculated (infested soil) were approximately 1.47 × 1011 per g soil, they were 1.34-1.42 × 105 per g soil after the application of A. torulosa, Anabaena laxa and A. torulosa-Bacillus sp. Increases in yield (ranging from 3 to 23%) due to various microbial inoculants relative to uninoculated controls illustrated their promise as plant growth-promoting and disease-suppressing agents. This study illustrates the modulation of rhizosphere ecology through microbial inoculants as a mechanism of disease suppression and sustaining plant growth. [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]