Haematological Assessment on Toxicity of Fungicide Hexaconazole on Post larvae of Macrobrachium rosenbergii (de Man)

Abstract

The objective of the study was to determine the LC50 (96 h) of the fungicide Taqat (Captan, Hexaconazole) on post larvae of Macrobrachium rosenbergii (de Man). Prawns of average length 1.98 cm were exposed to taqat at concentrations of 0, 0.02, 0.04, 0.06 and 0.08 mg L-1. The LC50 of Hexaconazole at 96 h was found to be 0.064 mg L-1. Total haemocyte count (THC) of prawns in response to exposure to sublethal concentrations of taqat increased in test groups (7.87±5.96 to 1877.5±1622.3) were noticed. Significant changes in physiological and behavioural patterns were noticed. Differential haemocyte count (DHC) showed elevated agranulocytes (63.66±6.60 to 81.76±1.60) when compared to granulocytes (5±1.7 to 34.72±3.6) in experimental groups. Changes in blood clotting time (30.00±2.32 to 166.66±2.88) were also noticed between control and test groups indicating possible signs of stress in exposed animals. Present results demonstrate the risks involved in farming of M. rosenbergii near rice farms where these fungicides are routinely used.