Potential of Metarhizium anisopliae and Beauveria bassiana in the control of tea termite Microtermes obesi Holmgren in vitro and under field conditions

Two strains of Metarhizium anisopliae (Metschnikoff) Sorokin and two strains of Beauveria bassiana (Ballsamo) Vuillemin were evaluated for their potential use as biological control agents against the tea termite Microtermes obesi Holmgren. The strains were screened for relative pathogenicity, and the median lethal time eliciting 50% mortality (LT₅₀) was calculated. In general, the M. anisopliae strains were more virulent with lower LT₅₀ values than B. bassiana strains. The LT₅₀ values ranged from 1.6 to 3.7 days. The median lethal concentrations (LC₅₀) of all the isolates were also determined. The M. anisopliae strains had low LC₅₀ values compared to B. bassiana strains. The LC₅₀ values ranged from 35 to 140 conidia per termite. The strains were also tested for survival under laboratory nest conditions. All the isolates exhibited the ability to grow, sporulate and produce an epizootic in treated nest material. Field applications of the isolates also produced promising results.     

Pathways of bacterial invasion and watermelon seed infection by Acidovorax citrulli

This study explored the pathways of ingress of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits, into watermelon seeds. Up until 7 days post‐inoculation (DPI), a significantly higher percentage of watermelon seeds was infected with A. citrulli when the bacteria were applied (c. 1 × 10⁶ colony‐forming units) to stigmas versus ovary pericarps of female flowers. Immunofluorescence microscopy showed that, with stigma inoculation, A. citrulli colonized style and ovary tissues by 1 DPI, and the bacteria co‐localized with pollen germ tubes in these tissues. With ovary pericarp inoculation, A. citrulli cells penetrated the epicarp and mesocarp tissues by 1 DPI but did not reach endocarp until 4 DPI. Finally, manual pollination followed by stigma inoculation led to >53% A. citrulli‐infected seed lots, while A. citrulli was not detected in seeds/ovules generated by stigma inoculation without pollination (chemically induced parthenocarpy). These results show that stigma inoculation results in faster colonization of watermelon ovules by A. citrulli than pericarp inoculation, even though there is no difference in the levels of infection in mature seeds. The data also indicate that pollen germ tubes play an important role in A. citrulli ingress into watermelon seeds via stigmas.     

EFFICACY OF SUPPLEMENTAL CALCIUM ON THE GROWTH OF THREE RICE GENOTYPES DIFFERING IN SALT TOLERANCE

The effect of supplemental calcium (Ca) on the growth of three rice genotypes PVSB9, NS15, and Pokkali were assessed. Different morphological characters were studied among which the percent relative- plant height, total tillers, root dry weight (RDW), shoot dry weight (SDW), and total dry matter (TDM) were higher in Pokkali and PVSB9, but lower in NS15 under different salinity and supplemental Ca levels. These morphological characteristics significantly decreased with increasing salinity levels grown at different Ca levels, but significantly increased with increasing supplemental Ca levels. The interaction effect of genotypes and salinity levels, and genotypes and Ca levels were significant, where a negative relationship with increasing salinity levels and a positive relationship with increasing supplemental Ca levels were found. The interaction effect of salinity and Ca levels on all morphological parameters was significant, where these characteristics increased due to increasing the supplemental Ca levels at all the levels of salinity.     

Remote sensing-based assessment of impact of Phailin cyclone on rice in Odisha,India

Assessing the nature and extent of damage due to natural calamities remains one of the thrust areas in monitoring resource inventory through remote sensing. The effect of the cyclone Phailin and the post-incessant rains during second fortnight of October 2013 on coastal Odisha was studied in terms of rice area flooded, submerged and damaged. Multi-temporal SAR data were analysed to obtain the rice mask, and from this rice mask, the flood affected rice area was determined. Taluka-wise and district-wise crop loss proportion was estimated, and the overall production loss has been estimated. SAR data aided in delineation of flooded regions, while AWiFS NDVI data of subsequent dates showed both continued inundation and crop vigour status post-flood time period. The ground truth indicated that a major portion of the inundated region was not rice but was typha grasses and harvested rice field which should not be accounted as damage to rice crop. The damage on crop yield was difficult to assess; however, the inundation of the crop at panicle initiation and flowering would have impact on grain filling (results in chaffiness) and was considered as completely damaged. Most of the current inundated rice regions fall in this category. It was estimated that a total of 0.167 million hectares and 0.37 million tons of rice crop was lost in the cyclone and floods. The district-level percentage area of rice flooded was communicated to State Remote Sensing Centre in four days timeframe. The overall accuracy obtained for the validation of the ground truth sites was 91.5 %.     

Purification of vitellogenin from the air breathing catfish, Clarias gariepinus

Vitellogenin (Vtg) is a female specific glycophospholipoprotein which can be induced both in male and female with estradiol and xeno-estrogens. The basic theme behind the purification of vitellogenin from the fish is to understand the evolutionary relationship and for the purification and characterization of the Vtg receptor. The male catfish, Clarias gariepinus was administrated with estradiol over a period of time for the synthesis of Vtg and the serum was collected. The Vtg was purified from the serum using a two step chromatographic technique. The serum was passed on to DEAE-ion exchange column and the protein was eluted using a salt gradient. The fractions containing the Vtg were pooled and passed onto a gel permeation chromatography column and the pure protein was obtained. The molecular weight is around 200 kDa on the SDS-PAGE and around 520 kDa on the native gel electrophoresis.