Effectiveness of Foray 48B over time after application against the painted apple moth

Abstract

Laboratory bioassays confirmed the effectiveness of aerial applications of Foray 48B (Btk) against PAM over Auckland during 20022003 When neonate larvae were fed on Acacia mearnsii seedling foliage on the day of application (0 DA) 7498 of larvae died Larval mortality then decreased with increasing time after the application of Btk to ca 50 at 67 DA and 30 at 1213 DA In similar experiments larval mortality was not affected by the height (15 m above ground level) from which leaves of sprayed mature A mearnsii were collected but did vary consistently between trees Persistence of Btk on mature trees in the open was apparently lower than on seedlings kept in a shaded insectary If an application resulted in high mean mortality across all trees at 0 DA larvae typically died for 67 DA; whereas following an application that resulted in comparatively low mean mortality at 0 DA larvae usually died for only 4 DA