1Entomology Research Unit, Department of Zoology, University of North Bengal, Darjeeling-734 430, West Bengal, India.
2Department of Zoology, Mizoram Central University, Tanhril, Aizawl -796 009, Mizoram, India.
The bio-efficacy of endosulfan (chlorinated hydrocarbons), monocrotophos (organophosphate) and fenpropathrin (synthetic pyrethroid) at common recommended dilution with different quality of water (Different pH level) as spray fluid was studied against H. theivora in field condition. The monocrotophos and fenpropathrin were more severely affected by alkaline water and decomposed much more rapidly than the endosulfan. Particularly in alkaline carrier water (pH 9–10) significantly reduced the efficacy of monocrotophos to the tune of 35.89% to 61.55% if immediately sprayed after mixing, and got reduce to 38.92- 68.06% if the insecticide solution was sprayed after 24 hr of mixing. Neutral and acidic carrier water solution did not induce fall in efficacy. It was cleared from the study that the spray rig if allowed to stand several hours (24hr) before spraying would cause a substantial reduction in their efficacy.
Endosulfan, monocrotophos, fenpropathrin quality of water, Helopeltis theivora and pH
