Efficacy of insecticides against major insect pests of potatoes in hot climates of Peru

Soil-incorporated and foliar-applied insecticides, alone and in combination, were tested in two different tropical sites of Peru. At San Ramon (altitude 800 m) major pests during the wet season were Diabrotica spp. and Myzus persicae. Soil-incorporated insecticides gave protection against Diabrotica but not M. persicae, and yields were significantly lower with these compared with the foliar-applied insecticide, carbofuran. Mean yield was inversely and significantly correlated with mean number of Diabrotica individuals per plant (r=0·989; 0·01 <P<0·05). The foliar-applied insecticide, season, major pests were Phthorimaea operculella, M. persicae and Feltia spp. Mean yield was inversely correlated with mean number of larval mines by P. operculella on foliage (r=0·976;0·02 <P<0·05). The foliar-applied insecticide methomyl, reduced pest damage and increased yields significantly. The major pests during the dry season at Yurimagus (altitude 180m) were Diabrotica spp. Foliar application of carbaryl alone, or in combination with soil-incorporated insecticides, was equally effective in reducing damage and yield loss. An inverse significant correlation (r=0·985; 0·01<P<0·02) for yield vs. damage from Diabrotica spp. was observed.     

Organochloride insecticide residues in air in Delhi,India

Regular monitoring of air at three different sites, namely, Netaji Nagar, Moti Nagar and Town Hall in the metropolitan city of Delhi, India from June, 1980 to May, 1982 revealed varying levels of residues of DDT and HCH. The concentration of total DDT residues varied from 4 to 232 ng m^?3 with an average of 60 ng m^?3. Total HCH ranged from 0 to 21797 ng m^?3 with an average of 438 ng m^?3. Comparatively higher levels of total DDT (73 ng M^?3) were detected at Moti Nagar, the site near a DDT factory. The total HCH was highest at Town Hall (931 ng m^?3). Normally, higher quantities of the residues of DDT and HCH were detected during October to December. The insecticide residues consisted mainly of p, p′-DDT, p, p′-DDE, o, p′-DDT and p, p′-DDD, α- and γ-HCH. Only p, p′-DDT and p, p′-DDE were detected in all the samples and accounted for the bulk of total DDT. The HCH residues were mainly due to the α-isomer. Generally the concentration of HCH was higher than DDT in the air samples collected during the survey.     

A Photosynthesis-Based Dry Deposition Modeling Approach

We present a dry deposition modeling approach that includesvegetation-atmosphere interactions through photosynthesis/carbonassimilation relationships. Gas deposition velocity (V _d) is calculated using an electrical resistance-analogapproach in a coupled soil-vegetation-atmosphere transfer (SVAT)model. For this, a photosynthesis-based surface evapotranspirationand gas exchange model is dynamically coupled to an atmospheric model with prognostic soil hydrology andsurface energy balance. The effective surface resistance(composed of aerodynamic, boundary layer, and canopy-basedresistances) is calculated for a realistic and fully interactiveestimation of gaseous deposition velocity over natural surfaces.Based on this coupled framework, the photosynthesis-based gasdeposition approach is evaluated using observed depositionvelocity estimates for ozone over a soybean field (C3photosynthesis pathway) and a corn field (C4 photosynthesispathway). Overall, observed V _d and modeled V _d show good qualitative and quantitative agreement.Results suggest that photosynthesis-based physiologicalapproaches can be adopted to efficiently develop depositionvelocity estimates over natural surfaces. Such a physiologicalapproach can also be used for generalizing results from fieldmeasurements and for investigating the controlling relationshipsamong various atmospheric and surface variables in estimatingdeposition velocity.     

Accelerated development of quality protein maize hybrid through marker‐assisted introgression of opaque‐2 allele

Vivek Maize Hybrid 9‐ a popular single‐cross hybrid developed by crossing CM 212 and CM 145 was released for commercial cultivation in India. The parental lines, being deficient in lysine and tryptophan, were selected for introgression of opaque‐2 allele using CML 180 and CML 170 as donor lines through marker‐assisted backcross breeding. The opaque‐2 homozygous recessive genotypes with >90% recovery of the recurrent parent genome were selected in BC₂F_2, and the seeds with <25% opaqueness in BC₂F₃ were forwarded for seed multiplication. Vivek Quality Protein Maize (QPM) 9, the improved QPM hybrid, showed 41% increase in tryptophan and 30% increase in lysine over the original hybrid. The grain yield of the improved hybrid was on par with the original hybrid. The newly improved QPM maize hybrid released in 2008 will help in reducing the protein malnutrition because its biological value is superior over the normal maize hybrids. This short duration QPM maize hybrid has been adopted in several hill states of North Western and North Eastern Himalayan regions.     

Physiochemical and Textural Alterations in Indian Squid (Loligo duvauceli) Mantle During Frozen Storage and Cooking

Textural variations in squid mantle and the role of proteins on texture during frozen storage and cooking were investigated. Myofibrillar protein (62.36%) and pepsin soluble collagen (10.70%) accounted for the major fraction of total protein (22.17%). The histochemistry of mantle tissue showed a mesh-like arrangement of myofibrillar proteins with a collagenous dermal layer and feebly passing collagen through myotome bundles. Texture profile analysis of unfrozen mantle suggested the first phase of hardening at 50°C with hardness 1 (H1) of 11.53 kgf and hardness 2 (H2) of 9.68 kgf; and the second phase of hardening with optimal texture and maximum juiciness at 70°C (H1, 8.11 kgf; H2, 7.13 kgf) that varied with extended frozen storage. Increased frozen storage and cooking led to protein denaturation and formation of new low molecular weight proteins as evidenced in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE); these possibly influenced the functional and microstructural properties of the tissue.     

Identification of QTLs associated with resistance to Phomopsis pod blight (Diaporthe toxica) in Lupinus albus

Phomopsis blight in Lupinus albus is caused by a fungal pathogen, Diaporthe toxica. It can invade all plant parts, leading to plant material becoming toxic to grazing animals, and potentially resulting in lupinosis. Identifying sources of resistance and breeding for resistance remains the best strategy for controlling Phomopsis and reducing lupinosis risks. However, loci associated with resistance to Phomopsis blight have not yet been identified. In this study, quantitative trait locus (QTL) analysis identified genomic regions associated with resistance to Phomopsis pod blight (PPB) using a linkage map of L. albus constructed previously from an F₈ recombinant inbred line population derived from a cross between Kiev-Mutant (susceptible to PPB) and {"type":"entrez-protein","attrs":{"text":"P27174","term_id":"14195583","term_text":"P27174"}}P27174 (resistant to PPB). Phenotyping was undertaken using a detached pod assay. In total, we identified eight QTLs for resistance to PPB on linkage group (LG) 3, LG6, LG10, LG12, LG17 and LG27 from different phenotyping environments. However, at least one QTL, QTL-5 on LG10 was consistently detected in both phenotyping environments and accounted for up to 28.2% of the total phenotypic variance. The results of this study showed that the QTL-2 on LG3 interacts epistatically with QTL-5 and QTL-6, which map on LG10 and LG12, respectively.     

In vitro induction and characterization of somaclonal variation for red rot and other agronomic traits in sugarcane

In the present investigation, optimal media compositions for enhancing the callus induction and subsequent plant regeneration were worked out in sugarcane (Saccharum spp. complex). The field grown somaclones were characterized for yield and quality contributing traits in comparison to donor variety CoJ 88. The MS + 2,4-D (4.0 mg/l) + kin (0.5 mg/l) + sucrose (30 g/l) was found to be the best for the callus induction among the nine media compositions used. The highest shoot regeneration was 34.65% on MS + BAP (0.5 mg/l) followed by 31.07% on MS + IAA (2.0 mg/l) + kin (0.5 mg/l) and the least 11.80% on MS + BAP (2.0 mg/l). The shoot elongation was optimum on MS + IBA (5.0 mg/l). The rooting was carried on MS + NAA (3.0 mg/l) + IBA (2.0 mg/l) + sucrose (70 g/l). The somaclones, on field evaluation, exhibited huge variability for characters viz., tiller number at 120 days of field transfer, number of millable canes, cane height, number of nodes and internodal length at time of harvest and also for HR Brix at 240 and 300 days after field transfer. In R₀ generation, the variations induced for the characters such as stalk height after 120 days, HR Brix after 240 and 300 days of field transfer were negatively skewed with most of somaclones having values higher than the population mean values thereby offering adequate scope for improvement cane and quality. Elite somaclones marked for each trait were reported. Out of 228 somaclones inoculated with Cf 08 pathotype of red rot in R₁, three were resistant, four were moderately resistant and 221 somaclones showed variable degree of susceptibility, whereas, to Cf 03 pathotype, fourteen were resistant, nineteen were moderately resistant and 195 showed variable degree of susceptibility. Three somaclones exhibited moderate resistance (MR) to both the pathotypes, whereas, donor variety CoJ 88 showed susceptible reaction. These somaclones will further enhance the germplasm for sugarcane breeding.     

Histopathological changes in giant freshwater prawn Macrobrachium rosenbergii (de Man 1879) fed with probiotic Bacillus licheniformis upon challenge with Vibrio alginolyticus

The effect of dietary supplementation of probiotic bacterium Bacillus licheniformis on the histopathological changes in Macrobrachium rosenbergii juveniles (4.0 ± 0.02 g) challenged with known pathogenic strain of Vibrio alginolyticus are reported. Two isocaloric basal diets supplemented with probiotic bacteria B. licheniformis (1.0 × 10⁹ cfu/g feed) and other without probiotic supplementation were fed to the M. rosenbergii juveniles for 45 days. The histological observations revealed no significant changes in the hepatopancreas and gut tissues of both the experimental and the control groups which indicate that the present bacterium is a safe candidate probiont for the host. Prawns were challenged with V. alginolyticus after 45 days of feeding with probiotic diet. The histopathological studies of the hepatopancreas revealed that M. rosenbergii fed with probiotic‐supplemented diet showed less changes as compared to the prawns fed with control diet on second and fourth day of post‐experimental challenge with V. alginolyticus. Histopathological observations revealed that the gills of the prawns fed with control diet were severely affected in comparison to the prawns fed with probiotic‐supplemented diet after challenging with V. alginolyticus. Results from this study revealed the improved protection by dietary incorporation of B. licheniformis in reducing the histopathological manifestations due to V. alginolyticus infection in freshwater prawn.