Bioefficacy of Insecticides Against Alfalfa Weevil, Hypera variabilis larvae in Kargil

A field trial to evaluate the efficacy of insecticides for the control of alfalfa weevil larvae was established at the Regional Agricultural Research Sub-Station SKUAST-K, Kargil, Ladakh in 2009. The mean number of alfalfa weevil larvae per 10 stems in each plot did not differ significantly and averaged between 1.3 to 2.5 larvae per stem before the application of insecticides. The mean number of alfalfa weevil larvae in the untreated control plots averaged from 15.00 to 26.6 larvae/10 stems on all sampling dates which are significantly higher than the number of alfalfa weevil larvae in all the insecticide treated plots which averaged from 0.00 to 3.00 larvae/10 stems. All the insecticide treatments reduced the mean number of alfalfa weevil larvae per 10 stems significantly, however no significant differences were observed among all the insecticide treatments. All the insecticides at their minimum recommended concentrations i.e., Chloropyriphos 20 EC @ 0.02%, Dimethoate 30 EC @ 0.03%, Malathion 50 EC @ 0.05% Endosulphan 35 EC @ 0.03% and Quinalphos 25 EC @ 0.04% reduced the mean number of alfalfa weevil larvae/10 stems quite significantly at all the sampling dates and were observed to be at par with their next two higher concentration used in the experiment. Moreover, all the insecticides gave efficient control of alfalfa weevil larvae for approximately 25 days after treatment.