ADV. BIORES.VOL 1 [2] DECEMBER 2010 131  Society of Education, India RESEARCH PAPER http://www.soeagra.com ISSN 0976-4585 Comparative Study of Acute Toxicity of BHC and Furadan on Mesocyclops leuckarti (Claus 1857) by LC 50 Analysis Poonam N. Kurve, Govind V. Kulkarni, * Kalpana D. Phal Department of Zoology and * Deparment of Statistics B. N. Bandodkar college of Science, Dnyandweep, Chendani Bunder Rd, Thane 400 601 Email:phalkalpana@hotmail.com,kurveng@yahoo.com INTRODUCTION In modern agricultural methodology, application of pesticides has been a regular practice to control destruction of crops by pests. However, as a secondary effect there pesticides cause adverse effect on living community around. Many of the pesticidal compounds are non-degradable and hence, accumulate in ecosystem resulting into water pollution and soil pollution. Water pollution due to drains of chemical in nearby water body show various consequences on aquatic organisms [1]. Planktonic organisms being small in size face a threat to their life. Further, they form important component of aquatic food chain. Due to biomagnifications, the situation aggravates and lethal effect on macro-organisms is also observed [2-9]. The Statistical analysis of the percent mortality for two pesticides were carried out to compare their toxicity. LC 50 was determined for both pesticides. Traditional way to determine was probit analysis. We fitted Weibul’s distribution and compared two pesticides for their toxicity by both the methods[6]. METHODS AND MATERIALS Experimental organisms i.e. Mesocyclops leuckarti were collected from freshwater body (Makhmali lake, Thane) by using net of mesh size 30m and then cultures in laboratory by phased fertilzation technique. The cultures of these organisms were maintained in glass tank. Adult males and females were taken from this stock culture and were used for LC 50 experiments (Table -1). Stock solutions of BHC and Furadan were also prepared in distilled water and dilutions were made as per requirements. Beakers of 50ml capacity containing 40ml pre-fertilized medium of required concentrations of pesticides BHC and Furadan from 0.01ppm to 15ppm were used. For LC 50 studies experimental organisms were exposed to the above said concentrations for time intervals of 2hrs, 24hrs, 48hrs, 72hrs and 96hrs. Different concentrations (to which experimental organisms were exposed) were decided on the basis of observations of experiments carried out for determining survival period.Ten adult animals were used for each concentration as well as for each time of exposure and the experiments were carried out in triplicates. RESULTS AND DISCUSSION The number of respondents to the pesticides was recorded. Experiments were carried out for different exposure hours namely 2 hours, 24 hours, 48 hours, 72 hours and 96 hours for doses of different concentrations of both pesticides. Percentage mortality was recorded (Table 1). ADVANCES IN BIORESEARCH, Vol 1 [2] DECEMBER 2010: 131 - 138 ABSTRACT An acute toxicity of two pesticides BHC and FURADAN was studied on a cyclopoid copepod, Mesocyclops leuckarti. At five different durations of exposure hours, doses of different concentrations were administered to these animals, and their mortality rates were recorded. With the help of statistical analysis and various plots on these data , the effect of these pesticides were studied and LC 50 were determined. It was concluded that BHC is more toxic than FURADAN. KEYWORDS: Confidence interval (CI) , Hazard rate , LC 50, Mesocyclops leuckarti, Weibull distribution.