Vector population manipulation for control of arboviruses – a novel prospect for India

India, the seventh largest country in the world, has diverse geographical and climatic regions with vast rural and peri‐urban areas. Many are experiencing an escalation in the spread and intensity of numerous human diseases transmitted by insects. Classically, the management of these vector‐borne diseases is underpinned by either chemical insecticides and/or environmental management targeted at the vector. However, these methods or their present implementation do not offer acceptable levels of control, and more effective and sustainable options are now available. Genetic strategies for the prevention of arbovirus transmission are most advanced for dengue and chikungunya, targeting their primary vector, Aedes aegypti. The national burden in terms of morbidity and mortality as a direct consequence of dengue virus in India is considered to be the largest worldwide, over 4 times that of any other country. Presently, new genetic technologies are undergoing field evaluation of their biosafety and efficacy in several countries. This paper discusses the merits of these approaches and argues for fair and transparent appraisal in India as a matter of urgency. Identification of any associated risks and their appropriate mitigation are fundamental to that process. © 2013 Society of Chemical Industry     

Heterosis in relation to genetic divergence in maize (Zea mays L.)

Summary The magnitude of heterosis was examined in relation to genetic divergence among 10 parents in a 10 × 10 diallel cross of maize. The 10 parents (varieties) were selected on the basis of multivariate analysis of quantitative characters using Mahalanobis' D²-statistic from a lot of 64 varieties of maize belonging to different geograshical regions of the world. The magnitude of heterosis for grain yield and its components was found to be higher with moderate (intermediate) parential diversity than with extreme ones. The results indicated that not only the genetic diversity but the high per se performance with respect to specific characters of interest should be taken into consideration also while selecting parents for hybridization.     

Prevalence,O-genotype and Shiga toxin (Stx) 2 subtype of Stx-producing Escherichia coli strains isolated from Argentinean beef cattle

The aims of this study were to investigate prevalence, O-genotype, and virulence gene profile including Shiga toxin (Stx) 2 gene-subtype of Stx-producing Escherichia coli (STEC) in beef cattle from the Bahía Blanca in Argentina. Rectal swabs were collected from 283 beef cattle in 2012. stx genes were detected in 90 (32%) out of the 283 rectal swabs by stx gene-specific PCR assay. The positive cases were 13 with stx1, 58 with stx2, and 19 with both stx1 and stx2. Among 90 stx gene-positive samples, 45 STEC strains were isolated, which included 3 stx1, 34 stx2, and eight stx1 and stx2 genes positive isolates. O-genotyping grouped 45 STEC strains into 19 different O-genotypes such as Og8, Og145, Og171, Og185 (4 from each), Og22, Og153, Og157 (3 from each) and others. Various stx2 gene-subtypes were identified in 42 STEC strains: 13 positive cases for stx2a, 11 for stx2c, 3 for stx2g, 10 for stx2a and stx2d, 4 for stx2a and stx2c, and 1 for stx2b, stx2c and stx2g. efaI gene, generally prevalent in clinical strains, was detected in relatively high in the STEC strains. These data suggest that stx2a and stx2c were distributed not only in O145 and O157 but also in minor O-genotypes of STEC in Argentina.     

Effect of supplementation of vitamin E,copper and zinc on the in vitro phagocytic activity and lymphocyte proliferation index of peripartum Sahiwal (Bos indicus) cows

To study the effect of vitamin E (VE), copper (Cu) and zinc (Zn) supplementation on the in vitro phagocytic activity (PA) and lymphocyte proliferation response (LPR) of blood neutrophils and lymphocytes, thirty Sahiwal pregnant cows (six in each group) in their late gestation at 30 days before the expected date of calving were selected from the NDRI experimental herd and supplemented with various micronutrients from 30 days before calving to 45 days after calving. Cows were supplemented individually with VE (1000 IU/cow/day), Cu (20 ppm/cow/day) and Zn (80 ppm/cow/day) and also with a combination of VE, Cu and Zn to study cumulative effect of all micronutrients. One group without any supplementation acted as a control. Blood neutrophils and lymphocytes were isolated and studied for their PA and LPR. Supplementation of micronutrients like VE, Cu, Zn and a combination of all these nutrients significantly (p < 0.01) increased the PA of experimental cows as compared to control (unsupplemented) cows during the pre‐partum period. During post‐partum, all the micronutrients (VE, Cu, Zn and their combination) showed a significant (p < 0.01) increase in the PA of experimental cows as compared to control cows. Of all the groups, significant (p < 0.01) and maximum PA was observed in the combination group followed by Zn‐supplemented group during both the pre‐ and post‐partum period. A significant (p < 0.01) increase in LPR of B lymphocytes was observed in combination‐supplemented group during the pre‐partum period and during both the pre‐ and post‐partum period in the Cu‐supplemented group.     

Efficacy of disinfectants and hand sanitizers against avian respiratory viruses

Disinfectants play a major role in the control of animal diseases by decontaminating the farm environment. We evaluated the virucidal efficacy of nine commonly used disinfectants on a nonporous surface contaminated experimentally with avian metapneumovirus (aMPV), avian influenza virus, or Newcastle disease virus (NDV). Phenolic compounds and glutaraldehyde were found to be the most effective against all three viruses. Quaternary ammonium compounds were effective against aMPV but not against the other two viruses. In addition, efficacy of commercially available hand sanitizers was evaluated on human fingers contaminated with aMPV and NDV. All three hand sanitizers tested were found to be effective against both viruses within 1 min of application on fingers.     

Carbofuran-induced biochemical changes in Clarias batrachus

The effect of carbofuran, an organo-carbamate pesticide, upon the level of protein as well as the activity of lactate dehydrogenase (EC 1.1.1.28, LDH) was studied by exposing the teleost fish, Clarias batrachus, to different subacute con-centrations (0·01 and 0·02 mg litre^-1) for 96 h and 15 days. The results showed a drastic decrease in the protein content in different body organs of the fish. The pesticide also caused a significant decrease in the level of activity of LDH in different body tissues of the fish, the effect being more pronounced in the gills, muscle, brain and liver than in kidney and heart. The decrease in protein content and the activity of LDH in fish tissues was more marked at the higher concentration of the pesticide for the longer duration of treatment. The results suggested that carbofuran has an effect at very low concentration (compared to its LC₅₀ value) possibly at the level of protein metabolism, and also inhibits the activity of LDH, the terminal glycolytic enzyme. © 1998 SCI     

Intergenotypic competition in mixed stands of spring wheat genotypes

Summary Grain yield and yield components were studied in the three spring wheat genotypes HD 2160 (dwarf), Kalyansona (semi-dwarf) and C 306 (tall) in pure stands as well as in their binary mixed stands during two years. The grain yields of the three genotypes in pure stands ranked as follows: HD 2160 > Kalyansona > C 306. Four mixed stands, 3:1 HD:K, 1:1 HD:C in the first year and 1:1 K:C, 1:3 K:C in the second year out-yielded the pure stand of the better component genotype by 4.4, 2.7, 3.3 and 0.8 percent, respectively. Out of the nine mixed stands four in the first year and seven in the second year out-yielded the midmonoculture yields and the increases ranged from 1 to 7.6 percent. Mixed stands were more stable than pure stands.The yield and yield components of the dwarf genotype HD 2160 scored less and those of the taller genotype C 306 scored higher in mixed stands. The semi-dwarf genotype Kalyansona yielded more with HD 2160 and less with C 306. Plant height but not high yielding ability conferred high competitive ability. With respect to competitive ability the three genotypes ranked as follows: C 306 > Kalyansona > HD 2160.The results illustrate the importance of intergenotypic competition in increasing crop production and reducing genotype-environment interactions. Such studies are important to agronomists as genotypes with high competitive ability can be useful to combat the weed problem. They are also important to plant breeders for predicting the fate of genotypes with low competitive ability in heterogeneous populations.     

Response of upland cotton (<Emphasis Type="Italic">G.hirsutum</Emphasis> L.) genotypes to drought stress using drought tolerance indices

Drought tolerance as such is often not considered to be an independent trait by plant breeders. The objective of this study was to evaluate eight drought tolerance indices, namely stress susceptibility index (SSI), yield stability index (YSI), yield reduction ratio (Yr), yield index (YI), tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI) in upland cotton (G. hirsutum L.) genotypes. For this purpose, 16 genotypes were sampled during the 2013-2014 growing seasons under both normal and drought-stress field conditions at the Main Cotton Research Station of Navsari Agricultural University, Surat, India. The drought tolerance indices were calculated based on seed cotton yield under drought stress and non-stress conditions. Mean comparison of drought tolerance indices and seed cotton yield validated the significant influences of drought stress on yield as well as significant differences among genotypes. Results of calculated correlation coefficients and multivariate analyses showed that GMP, MP and STI indices were able to discriminate drought-sensitive and tolerant genotypes. Cluster analysis using the drought-tolerance indices divided the 16 genotypes into tolerant and susceptible groups. Two genotypes, G.Cot.16 × H-1353/10 and H-1353/10 × G.Cot.16 gave good yield response under drought conditions leading to their stability during water stress conditions. Based on multivariate analyses using the indices individually or in combinations, it was possible to identify the most yield-stable genotypes across the environments. Overall, we concluded that GMP, MP and STI indices can be efficiently exploited not only for screening drought tolerance but also to identify superior genotypessuitable for both stress and non-stress field conditions.