Environmental factors influence the expression of resistance to sorghum midge, Stenodiplosis sorghicola

Host plant resistance is an effective means of controlling sorghum midge (Stenodiplosis sorghicola). We studied the influence of environmental factors on expression of resistance to sorghum midge in three midge-resistant and two midge-susceptible genotypes. Midge-resistant lines AF 28, ICSV 197, and TAM 2566 suffered 8.8 to 17.3% damage across seven sowings compared to 25.6% damage in ICSV 112, and 69.4% damage in CSH 5. Susceptibility of the midge-resistant lines (AF 28, ICSV 197, and TAM 2566) decreased with an increase in open pan evaporation, maximum and minimum temperatures, and solar radiation; while the midge-susceptible lines (ICSV 112 and CSH 5) showed a poor interaction with these factors. Midge damage in ICSV 197 showed a negative correlation with minimum temperature and relative humidity and positive correlation with sunshine hours, while the reverse was true for CSH 5. Grain growth rate between 0 and 3 days after anthesis was lower in crops sown on 1st October, when AF 28 and ICSV 197 suffered maximum midge damage. Maximum and minimum temperatures and maximum relative humidity influenced the moisture content of the grain, grain growth rate, and sorghum midge damage. There was considerable variation in genotype× environment interaction for expression of resistance to sorghum midge, and the implications of these results have been discussed in relation to development of sorghum cultivars with resistance to this insect

Degradation of the insecticidal toxin produced by Bacillus thuringiensis var. kurstaki by extracellular proteases produced by Chrysosporium sp.

Aims:  Some Cry proteins produced by the soil bacterium Bacillus thuringiensis (Bt) or by transgenic Bt plants persist in agricultural soils for an extended period of time, which may pose a hazard for nontarget soil organisms. The aims of our study were to screen for soil fungi capable of degrading the Cry1Ac toxin and to identify the mechanisms that lead to the inactivation of this protein.Methods and Results:  Of the eight fungal strains screened, only one, Chrysosporium sp., was found to produce extracellular proteases capable of degrading the 66-kDa Cry1Ac at the N-terminal end of amino acid 125 (alanine). The proteolytic products of the Cry1Ac toxin did not exhibit any insecticidal activity against Helicoverpa armigera, in contrast to its high toxicity exhibited in the native form.Conclusions:  Proteases elaborated by the Chrysosporium sp. degrade the Cry1Ac toxin in a way that it looses its insecticidal activity against H. armigera.Significance and Impact of the Study: Chrysosporium sp., a specific soil micro-organism capable of producing proteases that degrade the Cry1Ac toxin into inactive products under controlled conditions is being reported for the first time. Application of this observation needs to be further tested in field conditions

Climate Change Realities and Policy Coherence in SAT India

Climate change has emerged as a major threat to sustaining livelihoods. There is ample evidence that the occurrence and intensity of drought has increased over the years. The atmospheric temperature is rising significantly at an average rate of 0.01-0.06°C/year in the Indian semi-arid tropics (SAT). In India, the annual mean surface air temperature is projected to rise by 1.7°C to 2.0°C by 2030 (INCCA 2010)