Impairment of Haematological Profile of Channa Punctatus Exposed to Sodium Arsenite.

Channa punctatus is a common fresh water fish abundantly distributed in ponds, beels and canals of India. The fish is regularly consumed because of its high nutritional value. Heavy metals are common pollutants of the aquatic environment because of their persistent and tendency to concentrate in aquatic organisms. This freshwater fish is continuously exposed to arsenic toxicity as this metalloid enters the body through gills and arsenic contaminated food. Fresh water C. punctatus were exposed to different concentrations of sodium arsenite for varied span of time in controlled laboratory condition to measure physiological responses. Data is indicative of cellular stress in C. punctatus that may lead to decline population size in its natural habitat.

Characterization and Virulence of an Indigenous Soil Bacillus sp. Prospecting for Mosquito Control.

Aims: Aquatic habitat of the rice fields is the effective breeding site of the mosquitoes whose overcrowding would promote their pathogens. But no attention has been paid to these habitats for isolation and identification of the bacterial biocides. Therefore, the study was envisaged to isolate and identify the mosquitocidal bacteria from the unexplored rice field soil of the Burdwan district (a premier rice producer), West Bengal, India. It was also aimed to evaluate the virulence of the potent pathogenic organisms in the laboratory and field against the mosquitoes. Study Design: Laboratory and field study. Place and Duration of the Study: Parasitology and Microbiology Research Laboratory, Department of Zoology, The University of Burdwan, Burdwan 713104, West Bengal, India and Microbiology Laboratory, Crop Production Division, Central Rice Research Institute, Cuttack 753 006, Orissa, India. The study was conducted between June, 2011 to July 2012. Methodology: The soils were collected from the rice-fields, serially diluted up to 10-3 level, 100 μl suspension was plated on NA medium and incubated at 30±0.1ºC in the BOD incubator for 72 h. The colonies were checked under a phase-contrast microscope and those having spores were purified by dilution plating on NA plates. Phenotypic, biochemical and molecular characters of the bacteria were studied following standard methods. The mosquitocidal activity of the selected organism was assessed using different mosquito species both in the laboratory and field. Results: On the basis of phenotypic, biochemical and 16S rDNA (Acc. no. GU190368) analysis, the selected bacteria (Ts 116) was identified as Bacillus sp. In the laboratory, the LC50s of the Bacillus sp. Ts116 against late third instar larvae of An. subpictus, Ar. subalbatus and Cx. quinquefasciatus were (2.37, 2.2 and 9.6) X 106 bacteria/ml, respectively. After 7d, treatment with 100 ml suspension (containing 2.7x106 bacteria/ml) of bacteria/m3 breeding site effected 97.35, 95.65 and 100% mortality of An. subpictus, Ar. subalbatus and Cx. quinquefasciatus larvae, respectively. Conclusion: Indiscriminate use of chemical insecticides causes vector-resistance resulting in serious health and environmental hazards. The Bacillus sp. Ts116 (GU190368) of the rice fields had potential to be exploited in mosquito control programms.