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.

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 10 7 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 LC 50 and LC 90 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.

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Cotton leaf curl disease (CLCuD), caused by whitefly (Bemisiatabaci) transmitted singlestranded DNA viruses belonging to the Genus, Begomovirus (family, Geminiviridae) in association with satellite molecules; is responsible for major economic losses in cotton in three northwest (NW) Indian states Haryana, Punjab, and Rajasthan. Annual CLCuD incidences during 2012 to 2014 were estimated to be 37.5%, 63.6%, and 38.8% respectively. Cotton leaves were collected from symptomatic plants annually for three years and subjected to DNA isolation, followed by rolling circle amplification (RCA), cloning, and DNA sequencing of apparently full-length begomoviral genomes and associated betasatellites and alphasatellites. Among the thirteen CLCuD-begomoviral genomes recovered, eight were identified as Cotton leaf curl Multan virus-Rajasthan (CLCuMuV-Ra), one as-Pakistan (PK) and another as-Faisalabad (Fai), whereas, three were as Cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu), indicating that CLCuMuV-Ra was the most prevalent begomovirus species. Five of the eight CLCuMuV-Ra sequences were found to be recombinants. The CLCuMuV-Ra-associated satellites consisted of Cotton leaf curl Multan betasatellite (CLCuMB), and Gossypium darwinii symptomless alphasatellite (GDarSLA), and Croton yellow vein mosaic alphasatellite (CrYVMoA). The second most abundant helper virus species, CLCuKoV-Bu, was associated with CLCuMB and GDarSLA.

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Aim: To understand the effect of Cotton Leaf Curl Disease incidence and severity at various crop growth stages on Bollgaurd-II cotton hybrids having different levels of susceptibility and resistance and its effect on, seed cotton yield and fibre quality. Methodology: The effect of cotton leaf curl disease (CLCuD) incidence, severity and its progress on highly resistant to susceptible cultivars was compared. The loss of seed cotton yield (SCY) corresponding to CLCuD incidence at 80 DAS, 81-110 DAS, 111-140 DAS was estimated separately in each hybrid. The loss of fibre quality corresponding to CLCuD incidence at seven different stages, i.e., 50 to 140 days after sowing (DAS) was also calculated. Results: The highest relative area under disease progress curve (AUDPC) values of PDI were observed in Ankur 3028 (100%) and Ankur Jai BG II (83%), while the lowest values were recorded in highly resistant hybrids Yuva-841-2 (4.6%) and Bunty 2113-2 (13.8%). When the disease appeared up to 80 DAS compared to 110, 140 DAS the reduction range in SCY (4.6-62.4%), fibre length (23.9-29.9%), strength (21.4-30.1%) and uniformity (62.5-83%) was recorded to be higher in susceptible hybrids. The fibre length, strength, and uniformity were reduced in diseased plant (25.9 mm, 24.4 g/tex, 68.2%) when incidence took place at 50 DAS compared to disease-free plants (27.6mm, 25.9 g/tex, 72.9%). However, reduction in SCY, fiber length, fiber strength and uniformity at 80 DAS varied with respect to hybrid and their resistance category. Interpretation: These results provide the basis to prove the hypothesis that the yield loss is associated with the stage of CLCuD incidence and its severity in cotton hybrids with different levels of resistance as well as its genetic potential of a particular cotton cultivar. However, the extent of yield reduction within the resistant or susceptible category is also dependent on the yield potential of a particular cultivar. Thus, breeders must consider both the criteria-lower PDI /AUDPC and higher productivity to select high yielding cotton lines. Key words: Cotton, Disease index, Leaf Curl Disease, Virus