Studying the efficacy of fipronil (WG 80%) against alfalfa weevil, Hypera postica (Coleoptera: Curculionidae)

Abstract

The alfalfa weevil, Hypera postica Gyll. (Coleoptera: Curculionidae), is a key pest of alfalfa in different regions of the world where it causes sometimes complete crop destruction. Application of insecticides is the most important and major control method of this pest. The efficacy of fipronil (WG 80%), 50, 70 and 90 g/ha along with fosalon (EC 35%), 2.5 l/ha and malathion (EC 57%), 3 l/ha were assessed against this pest in the field based on a completely randomized block design. Based on Henderson-Tilton formula, on the fourteenth day after treatment, the minimum efficacy of fipronil, 50, 70 and 90 g/ha, fosalon, 2.5 l/ha and malathion, 3 l/ha bait was 80%, 89%, 98%, 76% and 75%, respectively. Results showed that fipronil (WG 80%) at 50-70 g/ha can be used against alfalfa weevil.