PYRETHROID RESISTANCE IN FIELD-COLLECTED BOLL-WEEVILS FROM SOUTHEAST ARKANSAS IN 1994

An adult vial test was used to determine the responses to selected ins ecticides of field-collected boil weevils from southeast Arkansas wher e control difficulties with pyrethroid insecticides were reported in 1 994. Resistance ratios at LC(50) and LC(90) were 8-27 fold and 2-8 fol d with the pyrethroids cyfluthrin and cypermethrin, respectively, in c omparison to a laboratory reference strain. There was about 2-4 fold t olerance to oxamyl, 0.2-1.4 fold tolerance to endosulfan, and 0.2 fold tolerance to azinphosmethyl in field-collected boil weevils compared to the reference strain. The high sensitivity of field boil weevils to azinphosmethyl suggests that organophosphorus insecticides may be the best choice in a boil weevil eradication program. These data in combi nation with those published earlier validate the use of the adult vial test to monitor insecticide resistance in the boil weevil and suggest the test may be useful. in the eradication program.