Effect of herbicides on Cyphoderus javanus (Hexapoda: Collembola) under laboratory conditions
Partha Pratim Chakravorty, Asraful Haque, Somanka Sanyal, Rupa Dasgupta
Cyphoderus javanus was used to evaluate toxicity of two herbicide formulations Pretilachlor (50 EC) and Pendimethalin (30 EC) under laboratory conditions. LC50 and LT50 value of Pretilachlor on Cyphoderus javanus could not be established at Recommended Agricultural Dose (RAD) of the chemical during an exposure period of 24 hrs. Twenty four hours LC50 value of Pendimethalin was less than its corresponding RAD and LT50 value was 7 hours. Significant reduction in hatching success was noted with the application of the herbicide formulation of Pendimethalin at all sublethal doses except 1/10th of LC50 in comparison to control. Juveniles of Cyphoderus javanus exposed to 1/6th, 1/8th and 1/10th of LC50 for Pendimethalin survived and exhibited increased moulting frequency in comparison to control. Test specimens required significantly less time to attain sexual maturity exposed to Pendimethalin in comparison to control.