Efficacy of two Toxicants as Bran Bait for the Bigheaded Grasshopper, 1990

Abstract

Two toxicants on wheat bran bait were compared in field cages for their efficacies against the bigheaded grasshopper, Aulocara elliotti in Belle Fourche, S. Dak. The dense vegetation in the test site was dominated by western wheatgrass, Agropyron smithii Rydb., blue gramma, Bouteloua gracilis (H. B. K.) and buffalograss, Buchloe dactyloides (Nutt.) Engelm. Field cages (1 m2) were placed on the test site and freed of grasshoppers and other predators. Lorsban (chlorpyrifos), formulated as 1 and 3% bran bait, and Carbaryl, formulated as 2% bran bait, were applied on 31 Jul to the cages at rates equivalent to 2 or 4 lb of bran flakes/acre to simulate field application. Each cage was then stocked with 20 females (ca. 10-d old adults) of Aulocara elliotti which had been starved for 24 h after being collected in the vicinity of the study site. Eight cages were used for each treatment and 16 for the untreated control. Grasshopper mortalities were recorded 5 DAT and the data were transformed using arcsin x prior to analysis.