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The incidence of Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae) was surveyed in production fields of cotton, Gossypium hirsutum L., in Tamil Nadu, India, from December 2021 to April 2022. Plants sampled in the crops were winter and summer planted, 45–95 days past seeding, and in the flowering to boll development stages. Whitefly counts from the sampling yielded a range of 4.4 to 8.9 adults and nymphs per 3 leaves (sample unit). The nymphs and adults collected from the fields were taxonomically confirmed using taxonomic characteristics obtained by photographs of live and slide-mounted specimens. Identification was further confirmed by molecular techniques using the mitochondrial Cytochrome Oxidase subunit I gene (COI) universal primer-based polymerase chain reaction (PCR) amplification and sequencing. The resulting dendrogram, constructed using MEGA-X and analyzed using the maximum likelihood method, yielded a single clade with sub-lineages of the specimens collected in this survey. Overall, the mean (± SD) duration of the entire life cycle of A. dispersus collected was 43.9 ± 2.4 d. Mean (± SD) length x width the developmental stages were 283.8 ± 13.3 μm x 167.0 ± 4.5 μm for eggs, 335.7 ± 19.3 μm x 266.9 ± 25.7 μm for first instars, 473.8 ± 21.6 μm x 349.8 ± 21.3 μm for second instars, 774.4 ± 15.11 μm x 440.2 ± 5.8 μm for third instars, 881.1 ± 16.7 μm x 634.7 ± 5.2 μm for fourth instars, and 970.0 ± 9.1 μm x 836.9 ± 12.7 μm for adults. [ABSTRACT FROM AUTHOR]

Clothianidin is drenched at planting to manage the termites of sugarcane. The application of organic manures at planting is also in vogue to conserve the soil moisture in the tropical ecosystem. Hence, the persistence behaviour of clothianidin was studied in the sandy clay loam soil of tropical sugarcane ecosystem under different organic manuring. The clothianidin residues persisted up to 90th DAT and reached below the limit of quantification (LOQ = 0.005 µg/g) on 105th DAT both in the manurial and non-manurial soils. The half-lives of clothianidin were in the range of 22.4–24.8 days in the manurial soils as against 21 days in the non-manurial soil, indicating the insignificant positive impact of organic manures on the soil persistence of clothianidin. The clothianidin residues in the soil were predicted to pose unacceptable to medium level of risk to earthworms during the course of its dissipation in the tropical sugarcane environment. [ABSTRACT FROM AUTHOR]

Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the sandy clay loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil. [ABSTRACT FROM AUTHOR]

Impact of organic manures, viz., composted coir pith, press mud, sugarcane trash, and farmyard manure (FYM) on the persistence of imidacloprid in the sandy clay loam soil of tropical sugarcane crop ecosystem, was studied by employing rapid sample preparation method and reversed phase HPLC. The recoveries of the method employed to determine the residues of imidacloprid in the soil were in the range of 94.5 ± 7.02–97.3 ± 2.94% across the five levels of fortification ranged between 0.005 and 0.5 μg/g. Imidacloprid was observed to persist in the soil manured with FYM and composted coir pith for 30 days with the half-life of 7.62 and 7.0 days, respectively as against 21 days with the half-life of 6.66 days in the non-manurial soil. The comparatively longer persistence of imidacloprid in the FYM and composted coir pith-applied soils was attributed to reduced leaching from the plow layer due to the adsorption of insecticide molecules by the added organic manures. [ABSTRACT FROM AUTHOR]

Surveys for weed killers in jute-based crop ecosystem was conducted at the research farm of ICAR-CRIJAF, Barrackpore during 2018 and 2019 cropping season. The nutgrass weevil, Athesapeuta cyperi caused 46.67 - 85.00% dead hearts in Cyperus rotundus in the jute ecosystem. This is the first report of A. cyperi on nutgrass in the jute ecosystem in West Bengal. This study throws a hope of using this weevil as a potential biocontrol agent against the most notorious weed the nut grass, which has been gradually developing resistance against many of the commonly used herbicides. [ABSTRACT FROM AUTHOR]

Cytochrome c oxidase I ( COI) gene-based DNA barcode was generated for sugarcane scale insect, Melanaspis glomerata (Green). The generated DNA barcode would certainly serve as an ideal diagnostic kit for M. glomerata. The barcode developed by us (GenBank Accession Number KR153875) would probably be the first for this species. The amino acid sequence of the M. glomerata COI fragment did not have any stop codon, and the uninterrupted open reading frame confirmed the quality of the DNA barcode. The extent of identity between the COI sequences of sugarcane scale and other three species of Diaspidids ( Aonidiella aurantii, A. taxus and Melanaspis bromeliae) varied between 87.37 and 88.75 %. Therefore, the barcode generated in this study could easily delineate M. glomerata from other armoured scales of economic importance. [ABSTRACT FROM AUTHOR]

Chlorantraniliprole 0.4 % GR has been in use for managing early shoot borer and top borer of sugarcane. Persistence and dissipation kinetics of granular formulation of chlorantraniliprole were studied in the soil of tropical sugarcane ecosystem by employing simple and sensitive analytical method. Limit of quantification of the method was 0.01 mg/kg and the recovery of chlorantraniliprole was in the range of 92.3–99.7%with RSD of 1.14–3.0 %. The initial deposit of chlorantraniliprole in the soil was 0.513 and 1.031 mg/kg for the recommended (75 g a.i./ha) and double the recommended (150 g a.i./ha) doses, respectively. The residues were quantified up to 30 days after treatment irrespective of the doses applied. Half-life (t1/2) was 6.60 and 6.73 days, respectively, for recommended and double the recommended doses of chlorantraniliprole. [ABSTRACT FROM AUTHOR]

Drought is a major limitation for rice production in rainfed ecosystems. Identifying quantitative trait loci (QTLs) linked to drought resistance provides opportunity to breed high yielding rice varieties suitable for drought-prone areas. Although considerable efforts were made in mapping QTLs associated with drought-resistance traits in rice, most of the studies involved indica × japonica crosses and hence, the drought-resistance alleles were contributed mostly by japonica ecotypes. It is desirable to look for genetic variation within indica ecotypes adapted to target environment (TE) as the alleles from japonica ecotype may not be expressed under lowland conditions. A subset of 250 recombinant inbred lines (RILs) of F8 generation derived from two indica rice lines (IR20 and Nootripathu) with contrasting drought-resistance traits were used to map the QTLs for morpho-physiological and plant production traits under drought stress in the field in TE. A genetic linkage map was constructed using 101 polymorphic PCR-based markers distributed over the 12 chromosomes covering a total length of 1,529 cM in 17 linkage groups with an average distance of 15.1 cM. Composite interval mapping analysis identified 22 QTLs, which individually explained 4.8–32.2% of the phenotypic variation. Consistent QTLs for drought-resistance traits were detected using locally adapted indica ecotypes, which may be useful for rainfed rice improvement. [ABSTRACT FROM AUTHOR]

InHelicoverpa armigera, withdrawal of selection pressure resulted in a two- to fourfold increase in susceptibility to synthetic pyrethroids and continuous selection enhanced the resistance level by four- to fivefold to the respective pyrethroids at the end of the 14th generation. Populations selected for resistance to one pyrethroid showed positive cross-resistance to all other pyrethroids, but no cross-resistance to endosulfan and thiodicarb. There was a significant increase in mixed-function oxidase activity with advancing generation suggesting its possible role in the positive cross-resistance among the pyrethroids. The induction of carboxyl esterases in pyrethroid-selected populations may have resulted in the activation of indoxacarb, thereby accounting for the observed negative cross-resistance. [ABSTRACT FROM AUTHOR]

Cytokinins induced haustoria formation in excised 10-mm segments of Cuscuta vine, the subapical 25-to-50-mm region being most responsive, producing a mean of 4-6 haustoria per segment. The order of effectiveness of cytokinins continuously applied (72 h) was 6-benzylaminopurine (BA) ⩾ isopentenyladenine (iP) ≫ zeatin (Z). Ribosides of BA and Z were as effective as the bases, whereas riboside of iP ([9R]iP) was half as effective as iP. Haustoria induction was influenced by weather and seasonal conditions at the time of vine collection; materials obtained on warm, sunny days responded better than those obtained on rainy, cloudy, or cool days. Haustoria were induced equally well all around the segment, and no thigmostimulus was needed for induction. p ]A 10-min pulse of 100 μM BA induced half as many haustoria as a 60-min pulse or continuous application of BA. White light inhibited haustoria induction elicited by a short (30-min) pulse of BA, whereas a longer (120-min) BA application overcame this light inhibition. Auxins (IAA or NAA, 1-10 μM), gibberellin (GA, 1-10 μM), ethylene (as ethrel, 10-100 μM), and abscisic acid (ABA, 100 μM) were individually inhibitory (60-80%) with respect to haustoria induction when given continuously with 50 μM BA. A 60-min pulse of auxins (10 μM), GA (100 μM), or ethrel (10 μM), given at various time intervals during or after a 60-min pulse of 100 μM BA, showed that inhibition was maximal (70-95%) between 4 and 16 h of BA application and negligible (GA) or much reduced (auxin, ethrel) at 20 h, indicating a 'commitment' to haustoria formation by this time. [ABSTRACT FROM AUTHOR]

Cuscuta stem (vines) exhibits two modes of growth-longitudinal elongation forming free-hanging vines, or coiling growth to twine around the host. The elongation zone of free-hanging vine extended up to 160 mm from the stem apex and in vivo growth rate (during 8 h of growth) was maximal in the 20-to-40-mm region. While gibberellic acid (GA) or fusicoccin (FC) could maintain (GA) or enhance (FC) the growth rate of apical (10 or 25 mm) segments, indole-3-acetic acid (IAA) (10 μM) induced growth only in subapical (5-160 mm) segments. In vitro growth rate induced by IAA (10 μM) was similar to the in vivo growth rate up to 40 mm. Thereafter, up to 100 mm, IAA induced growth rate exceeded in vivo growth. p ]Subapical segments (∼13 mm) from 5- to 40-mm regions responded to a cytokinin (BA, Z, or iP) or to low IAA (0.1 μM) with curved growth, whereas the segments grew straight in the presence of high IAA (10 μM). Curvature (measured as the angle subtended at the center of the circle of which the segment formed an arc) induced by BA and low (0.1 μM) IAA was greater than either added separately. Besides, segments induced to curve in BA + low-IAA solution could be made to straighten out by transferring to a solution containing high IAA (10 μM) with or without BA. Thus in vivo patterns of straight and coiling growth could be mimicked reversibly in vitro by adjusting the relative concentrations of cytokinin and auxin; low auxin and cytokinin induced coiling growth, whereas high auxin and cytokinin induced straight growth. p ]Beyond 40 mm, BA had no growth-promoting or curvative-inducing effect. Cuscuta vine segments thus showed sequential sensitivity to applied hormones, the apical region (0-25 mm) to GA, the subapical (5-40 mm) region to BA and IAA and the region beyond (40-160 mm) to IAA alone. [ABSTRACT FROM AUTHOR]

A simple and sensitive analytical method has been developed and validated for the determination of trace amounts of imidacloprid in/on sugarcane sett, stalk and leaf. The method optimized in the present study requires less volume of organic solvent and time. Hence, this method is suitable for high-throughput analyses involving large number of samples. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.003 and 0.01 mg/kg, respectively. The recovery and relative standard deviation were more than 93 % and less than 4 %, respectively. Thus, it is obvious that the analytical method standardized in this study is more precise and accurate enough to determine the residues of imidacloprid in sugarcane sett, stalk and leaf. The dissipation and translocation of imidacloprid residues from treated cane setts to leaf and stalk were studied by adopting this method. In sugarcane setts, the residues of imidacloprid persisted up to 120 days with half-life of 15.4 days at its recommended dose (70 g a.i./ha). The residues of imidacloprid were found to be translocated from setts to stalk and leaf. The imidacloprid residues were detected up to 105 days in both leaf and stalk. Dipping of sugarcane setts in imidacloprid at its recommended dose may result in better protection of cane setts and established crop because of higher initial deposit (>100 mg/kg) and longer persistence (>120 days). [ABSTRACT FROM AUTHOR]